Cyclohexane derivatives

Information

Patent Grant
4985583

References
Source

Patent Number
4,985,583
Date Filed
Tuesday, April 7, 1987
37 years ago
Date Issued
Tuesday, January 15, 1991
33 years ago

Inventors
Original Assignees
- MERCK & CO., INC
Examiners
- Stoll; Robert L.
- Treanor; Richard
Agents
- Millen, White & Zelano

CPC
US Classifications
Field of Search
- US
- 252 29901
- 252 2995
- 252 29961
- 252 29962
- 252 29963
- 350 350 R
- 558 426
- 558 431
- 544 241
- 544 242
- 544 295
- 544 296
- 544 298
- 544 336
- 544 357
- 546 186
- 546 187
- 546 189
- 546 190
- 546 191
- 546 192
- 546 193
- 546 194
- 546 255
- 546 256
- 546 275
- 546 276
- 546 286
- 546 287
International Classifications
- C07C25500
- C09K1952

Information

Abstract

New cyclohexane derivatives of the formula IR.sup.1 --A.sup.1 --Z.sup.1 --A.sup.2 --R.sup.2 IwhereinR.sup.1 and R.sup.2 are each H, an unsubstituted or substituted alkyl group with 1-15 C atoms, it also being possible for one or two non-adjacent CH.sub.2 groups to be replaced by at least one grouping from the group comprising --O--, --CO--, --O--CO--, --CO--O--, --C.tbd.C--, --CH.dbd.CH--, --S--, --SO-- and --SO.sub.2 --, F, Cl, Br, CN or R.sup.3 --(A.sup.3).sub.p --Z.sup.2 --,A.sup.1 is --A--, --A.sup.4 --Z.sup.3 --A-- or --A--Z.sup.3 --A.sup.4 --,A is a 1,4-cyclohexylene group which is substituted in the 1- and/or 4-position by unsubstituted or substituted alkyl or fluorinated alkyl with in each case 1-5 C atoms, it also being possible for one or two non-adjacent CH.sub.2 groups to be replaced by one grouping from the group comprising --O--, --CO--, --O--CO--, --CO--O--, --C.tbd.C--, --CH.dbd.CH--, --S--, --SO-- and --SO.sub.2 --, or by F, Cl, Br, CN and/or --CHO, and which can carry 1 or 2 further substituents,A.sup.2, A.sup.3 and A.sup.4 in each case denote 1,4-phenylene which is unsubstituted or substituted by one or two F and/or Cl atoms and/or CH.sub.3 groups and/or CN groups, it also being possible for one or two CH groups to be replaced by N atoms, 1,4-cyclohexylene, it also being possible for one or two non-adjacent CH.sub.2 groups to be replaced by O atoms, 1,4-cyclo-1-enyl, 1,3-dithiane-2,5-diyl, piperidine-1,4-diyl, 1,4-bicyclo(2,2,2)-octylene, unsubstituted or CN-substituted decahydronaphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl or --A--,Z.sup.1, Z.sup.2 and Z.sup.3 each are --CO--O--, --O--CO--, --OCH.sub.2 --, --CH.sub.2 O--, --CH.sub.2 CH.sub.2 --, substituted ethylene or a single bond,R.sup.3 is H, an unsubstituted or substituted alkyl group with 1-15 C atoms, it also being possible for one or two non-adjacent CH.sub.2 groups to be replaced by a grouping from the group comprising --O--, --CO--, --O--CO--, --CO--O--, --C.tbd.C--, --CH.dbd.CH--, --S--, --SO-- and --SO.sub.2 --, F, Cl, Br or CN andp is 1 or 2,and, if p=2, the groups A.sup.3 can be identical or different, and the acid addition salts of the basic compounds of this type, are suitable for use as components of liquid crystal dielectrics.

Description

Claims

1. A cyclohexane derivative of the formula
R.sup.1 --A.sup.1 --Z.sup.1 --A.sup.2 --R.sup.2
wherein
R.sup.1 and R.sup.2 independently are (a) C.sub.1-15 -alkyl, (b) C.sub.1-15 -alkyl substituted by halo or CN, (c) C.sub.1-15 -alkyl wherein one or two non-adjacent CH.sub.2 groups are replaced by at least one of --O--, --CO--, --O--CO--, --CO--O--, --C.tbd.C--, --CH.dbd.CH--, --S--, the maximum number of C-atoms still being 15, (d) F, (e) Cl, (f) Br, (g) CN or (h) R.sup.3 --(A.sup.3).sub.p --Z.sup.2 --,
A.sup.1 is --A--, --A.sup.4 --Z.sup.3 --A--or --A--Z.sup.3 --A.sup.4 --,
A is 1,4-cyclohexylene which is additionally substituted in the 1- or 4-position by CN,
A.sup.2, A.sup.3 in each case independently are (a) 1,4-and A.sup.4 phenylene, (b) 1,4-phenylene substituted by one or two F, Cl, CH.sub.3 or CN, (c) any of groups (a) or (b) wherein one or two CH groups are replaced by N atoms, (d) 1,4-cyclohexylene, (e) 1,4-cyclohexylene wherein one or two non-adjacent CH.sub.2 groups are replaced by O-atoms, (f) 1,4-cyclohex-1-enyl,
Z.sup.1, Z.sup.2 each independently are --CO--O--, --O--CO--,
and Z.sup.3 --OCH.sub.2 --, --CH.sub.2 O--, --CH.sub.2 CH.sub.2 --or a single bond,
R.sup.3 is (a) C.sub.1-15 -alkyl, (b) C.sub.1-15 -alkyl, substituted by halo or CN, (c) a group (a)-(b) wherein one or two non-adjacent CH.sub.2 groups are replaced by one of --O--, --CO--, --O--CO--, --CO--O--, --C.tbd.C--, --CH.dbd.CH--or --S--, the maximum number of C-atoms still being 15, (d) F, (e) CI, (f) Br or (g) CN and
is 1 or 2,
and when p=2, the groups A.sup.3 can be identical or different.
2. A compound of claim 1 of the formula
R.sup.1 --A--A.sup.2 --R.sup.2
or
R.sup.1 --A--Z.sup.1 --A.sup.2 --R.sup.2
3. A compound of claim 1 of the formula
R.sup.1 --A.sup.4 --A--A.sup.2 --R.sup.2
R.sup.1 --A--A.sup.4 --A.sup.2 --R.sup.2
R.sup.3 --A.sup.3 --A--A.sup.2 --R.sup.2
R.sup.1 --A--A.sup.2 --A.sup.3 --R.sup.3
R.sup.1 --A.sup.4 --Z.sup.3 --A--A.sup.2 --R.sup.2
R.sup.1 --A--Z.sup.3 --A.sup.4 --A.sup.2 --R.sup.2
R.sup.1 --A--Z.sup.1 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.1 --A.sup.4 --Z.sup.3 --A--A.sup.2 --R.sup.2
R.sup.1 --A--Z.sup.3 --A.sup.4 --A.sup.2 --R.sup.2
R.sup.1 --A.sup.4 --A--Z.sup.1 --A.sup.2 --R.sup.2
R.sup.1 --A--A.sup.4 --Z.sup.1 --A.sup.2 --R
R.sup.3 --A.sup.3 --A--Z.sup.1 --A.sup.2 --R.sup.2
R.sup.1 --A--A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A--A.sup.2 --R.sup.2
R.sup.3 --A.sup.3 --Z.sup.2 --A--Z.sup.1 --A.sup.2 --R.sup.2
R.sup.1 --A--Z.sup.1 --A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.1 --A.sup.4 --Z.sup.3 --A--Z.sup.1 --A.sup.2 --R.sup.2 or
R.sup.1 --A--Z.sup.3 --A.sup.4 --Z.sup.1 --A.sup.2 --R
4. A compound of claim 1 of the formula
R.sup.3 --A.sup.3 --A.sup.4 --A--A.sup.2 --R.sup.2
R.sup.3 --A.sup.3 --A--A.sup.4 --A.sup.2 --R.sup.2
R.sup.1 --A.sup.4 --A--A.sup.2 --A.sup.3 --R.sup.3
R.sup.1 --A--A.sup.4 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A--A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A--A.sup.2 --R.sup.3
R.sup.1 --A--A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A--A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A--Z.sup.1 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A--Z.sup.1 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A--A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.1 --A--A.sup.4 --Z.sup.1 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.1 --A.sup.4 --A--Z.sup.1 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A.sup.4 --A--Z.sup.1 --A.sup.2 --R.sup.2
R.sup.3 --A.sup.3 --A--A.sup.4 --Z.sup.1 --A.sup.2 --R.sup.2
R.sup.1 --A.sup.4 --A--A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.1 --A--A.sup.4 --A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A.sup.4 --A--A.sup.2 --R.sup.2
R.sup.3 --A.sup.3 --Z.sup.2 --A--A.sup.4 --A.sup.2 --R.sup.2
R.sup.3 --A.sup.3 --A--A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A--A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A.sup.3 --A--Z.sup.1 --A.sup.2 --R.sup.2
R.sup.3 --A.sup.3 --A.sup.4 --Z.sup.3 --A--A.sup.2 --R.sup.2
R.sup.3 --A.sup.3 --A--Z.sup.3 --A.sup.4 --A.sup.2 --R.sup.2
R.sup.1 --A--A.sup.2 --Z.sup.2 --A.sup.3 --A.sup.3 --R.sup.3
R.sup.1 --A.sup.4 --Z.sup.3 --A--A.sup.2 --A.sup.3 --R.sup.3
R.sup.1 --A--Z.sup.3 --A.sup.4 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A.sup.3 --Z.sup.2 --A--A.sup.2 --R.sup.2
R.sup.1 --A--Z.sup.1 --A.sup.2 --A.sup.3 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A.sup.4 --A--Z.sup.1 --A.sup.2 --R.sup.2
R.sup.3 --A.sup.3 --Z.sup.2 --A--A.sup.4 --Z.sup.1 --A.sup.2 --R.sup.2
R.sup.1 --A.sup.4 --A--Z.sup.1 --A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.1 --A--A.sup.4 --Z.sup.1 --A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A--Z.sup.1 --A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A--A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A--Z.sup.1 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A.sup.4 --Z.sup.3 --A--Z.sup.1 --A.sup.2 --R.sup.2
R.sup.3 --A.sup.3 --A--Z.sup.3 --A.sup.4 --Z.sup.1 --A.sup.2 --R.sup.2
R.sup.1 --A.sup.4 --Z.sup.3 --A--A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.1 --A--Z.sup.3 --A.sup.4 --A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A.sup.4 --Z.sup.3 --A--A.sup.2 --R.sup.2
R.sup.3 --A.sup.3 --Z.sup.2 --A--Z.sup.3 --A.sup.4 --A.sup.2 --R.sup.2
R.sup.1 --A.sup.4 --Z.sup.3 --A--Z.sup.1 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.1 --A--Z.sup.3 --A.sup.4 --Z.sup.1 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A.sup.3 --Z.sup.2 --A--Z.sup.1 --A.sup.2 --R.sup.2
R.sup.1 --A--Z.sup.1 --A.sup.2 --Z.sup.2 --A.sup.3 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A--Z.sup.1 --A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A.sup.4 --Z.sup.3 --A--Z.sup.1 --A.sup.2 --R.sup.2
R.sup.3 A.sup.3 --Z.sup.2 --A--Z.sup.3 --A.sup.4 --Z.sup.1 --A.sup.2 --R.sup.2
R.sup.1 --A.sup.4 --Z.sup.3 --A--Z.sup.1 --A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3 or
R.sup.1 --A--Z.sup.3 --A.sup.4 --Z.sup.1 --A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
5. A phase of claim 1 of the formula
R.sup.3 --A.sup.3 --A.sup.4 --A--A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A--A.sup.4 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A.sup.4 --A--A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A--A.sup.4 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.1 --A--A.sup.4 --A.sup.2 --A.sup.3 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A.sup.4 --A--A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A--A.sup.4 --A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A.sup.4 --A--Z.sup.1 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A--A.sup.4 --Z.sup.1 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A.sup.4 --A--A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A--A.sup.4 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A.sup.4 --A--Z.sup.1 --A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A--A.sup.4 --Z.sup.1 --A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A.sup.4 --A--A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A--A.sup.4 --A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A.sup.4 --A--Z.sup.1 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A--A.sup.4 --Z.sup.1 --A.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A.sup.4 --A--Z.sup.1 --A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --Z.sup.2 --A--A.sup.4 --Z.sup.1 --A.sup.2 --Z.sup.2 --A.sup.3 --R.sup.3
R.sup.1 --A.sup.4 --Z.sup.3 --A--Z.sup.1 --A.sup.2 --Z.sup.2 --A.sup.3 --A.sup.3 --R.sup.3
R.sup.1 --A--Z.sup.3 --A.sup.4 --Z.sup.1 --A.sup.2 --Z.sup.2 --A.sup.3 --A.sup.3 --R.sup.3
R.sup.3 --A.sup.3 --A.sup.3 --Z.sup.2 --A--Z.sup.1 --A.sup.2 --Z.sub.2 --A.sup.3 --R.sub.3 or
R.sup.3 --A.sup.3 --Z.sup.2 --A--Z.sup.1 --A.sup.2 --Z.sup.2 --A.sup.3 --A.sup.3 --R.sup.3
6. A phase of claim 1 of the formula
R.sup.1 --Phe--Z.sup.1 --A-R.sup.2
R.sup.1 --Cy--Z.sup.1 --A--R.sup.2
R.sup.1 --Dio--Z.sup.1 --A--R.sup.2
R.sup.1 --Pyr--Z.sup.1 --A--R.sup.2
R.sup.1 --Phe--Z.sup.1 --A--Z.sup.2 --Phe-R.sup.2
R.sup.1 --Dio--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2
R.sup.1 --Cy--Z.sup.1 --A--Z.sup.2 --Phe--R.sup.2
R.sup.1 --Cy--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2
R.sup.1 --Phe--Phe--Z.sup.1 --A--R.sup.2
R.sup.1 --Phe--Cy--Z.sup.1 --A--R.sub.2
R.sup.1 --Cy--Phe--Z.sup.1 --A--R.sup.2
R.sup.1 --Cy--Cy--Z.sup.1 --A--R.sup.2
R.sup.1 --Phe--Phe--Z.sup.1 --A--Z.sup.2 --Phe-R.sup.2
R.sup.1 --Phe--Phe--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2
R.sup.1 --Phe--Cy--Z.sup.1 --A--Z.sup.2 --Phe--R.sup.2
R.sup.1 --Phe--Cy--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2
R.sup.1 --Cy--Phe--Z.sup.1 --A--Z.sup.2 --Phe--R.sup.2
R.sup.1 --Cy--Phe--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2
R.sup.1 --Cy--Cy--Z.sup.1 --A--Z.sup.2 --Phe--R.sup.2
R.sup.1 --Cy--Cy--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2
wherein the Phe is 1,4-phenylene, Cy is 1,4-cyclohexylene, Dio is 1,3-dioxane-2,5-diyl and Pyr is pyrimidine-2,5-diyl.
7. A compound of claim 1 of the formula
R.sup.1 --(A.sup.1).sub.m --Z.sup.1 --A--Z.sup.2 --(A.sup.2).sub.n --R.sup.2
wherein
R.sup.1 and R.sup.2 are each independently, C.sub.1-10 straight chain alkyl or C.sub.1-10 branched alkyl of only one chain branching, in each of which one or two CH.sub.2 groups is optionally replaced by 0 atoms; or --O--COR;
A.sup.1 and A.sup.2 are each independently 1,4-phenylene, which is unsubstituted or substituted by 1-4 F atoms; or 1,4-cyclohexylene;
A is 1,4-cyclohexylene which is additionally substituted in the 1-position or in the 4-position by CN;
Z.sup.1 and Z.sup.2 are each independently --CO--O--, --O--CO--, --CH.sub.2 CH.sub.2 --, --OCH.sub.2 --, --CH.sub.2 O-- or a single bond;
R is alkyl of 1-5 C atoms;
m is 1 or 2 and n is 0 or 1, wherein when m is 2, the two A.sup.1 groups are identical or different from one another.
8. A compound of claim 7 of the formula
R.sup.1 --A.sup.1 --Z.sup.1 --A--Z.sup.2 --R.sup.2.
9. A compound of claim 7 of the formula
R.sup.1 --A.sup.1 --Z.sup.1 --A--Z.sup.2 --A.sup.2 --R.sup.2.
10. A compound of claim 7 of the formula
R.sup.1 --(A.sup.1).sub.2 --Z.sup.1 --A--Z.sup.2 --R.sup.2.
11. A compound of claim 7 of the formula
R.sup.1 --(A.sup.1).sub.2 --Z.sup.1 --A--Z.sup.2 --A.sup.2 --R.sup.2.
12. A compound of claim 7 of the formula
R.sup.1 --Phe--Z.sup.1 --A--Z.sup.2 --R.sup.2 or
R.sup.1 --Cy--Z.sup.1 --A--Z.sup.2 --R.sup.2
wherein Phe is 1,4-phenylene, and Cy is 1,4-cyclohexylene.
13. A compound of claim 7 of the formula
R.sup.1 --Phe--Z.sup.1 --A--Z.sup.2 --R.sup.2 or
R.sup.1 --Cy--Z.sup.1 --A--Z.sup.2 --R.sup.2
wherein Phe is 1,4-phenylene, and Cy is 1,4-cyclohexylene.
14. A compound of claim 7 of the formula
R.sup.1 --Phe--Z.sup.1 --A--Z.sup.2 --Phe--R.sup.2
R.sup.1 --Cy--Z.sup.1 --A--Z.sup.2 --Phe--R.sup.2
R.sup.1 l--Cy--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2
R.sup.1 --Phe--Phe--Z.sup.1 --A--Z.sup.2 --R.sup.2
R.sup.1 --Phe--Cy--Z.sup.1 --A--Z.sup.2 --R.sup.2
R.sup. l--Cy--Phe--Z.sup.1 --A--Z.sub.2 --R.sub.2
R.sup.1 --Cy--Cy--Z.sup.1 --A--Z.sup.2 --R.sup.2
R.sup.1 --Phe--Phe--Z.sup.1 --A--Z.sup.2 --Phe--R.sup.2
R.sup.1 --Phe--Phe--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2
R.sup.1 --Phe--Cy--Z.sup.1 --A--Z.sup.2 --Phe--R.sup.2
R.sup.1 --Phe--Cy--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2
R.sup.1 --Cy--Phe--Z.sup.1 --A--Z.sup.2 --Phe--R.sup.2
R.sup.1 --Cy--Phe--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2
R.sup.1 --Cy--Cy--Z.sup.1 --A--Z.sup.2 --Phe--R.sup.2 or
Rhu 1--Cy--Cy--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2
wherein Phe is 1,4-phenylene, and Cy is 1,4-cyclohexylene.
15. A compound of claim 7 wherein R.sup.1 and R.sup.2, independently, are each alkyl or oxa-containing alkyl.
16. A compound of claim 7 wherein A.sup.1 and A.sup.2, independently, are each 1,4-cyclohexylene or 1,4-phenylene.
17. A compound of claim 7 wherein Z.sup.1 and Z.sup.2 are each single bonds.
18. A compound of claim 7 wherein m is 1 and n is 0.
19. A compound of claim 7 of the formula
R.sup.1 --A.sup.1 --Z.sup.1 --A--R.sup.2
R.sup.1 --Phe--A--R.sup.2
R.sup.1 --Phe--CO--O--A--R.sup.2
R.sup.1 --Phe--O--CO--A--R.sup.2
R.sup.1 --Phe--CH.sub.2 CH.sub.2 --A--R.sup.2
R.sup.1 --Phe--O--CH.sub.2 --A--R.sup.2
R.sup.1 l--Phe--CH.sub.2 --O--A--R.sup.2
R.sup.1 --Cy--A--R.sup.2
R.sup.1 --Cy--CO--O--A--R.sup.2
R.sup.1 --Cy--O--CO--A--R.sup.2
R.sup.1 --Cy--CH.sub.2 --CH.sub.2 --A--R.sup.2
R.sup.1 --Cy--O--CH.sub.2 --A--R.sup.2
R.sup.1 --Cy--CH.sub.2 --O--A--R.sup.2 or
R.sup.1 --Phe--Phe--A--R.sup.2
wherein Phe is 1,4-phenylene, and Cy is 1,4-cyclohexylene.
20. A compound of claim 7 wherein the groups R.sup.1 --(A.sup.1).sub.m --Z.sup.1 -- and --Z.sup.2 --(A.sup.2).sub.n --R.sup.2 are in the trans-position in relation to one another, and the 1-substitutent on A is in the cis-position in relation to the group opposite to it.
21. r-1-cyano-1-pentyl-cis-4-(trans-4-pentylcyclohexyl)-cyclohexane, a compound of claim 7.
22. A compound of claim 7 of the formula ##STR6## wherein R.sup.1 is alkyl of 2-7 C atoms, R.sup.2 is alkyl of 2-10 C atoms, or alkyl of 2-10 C atoms wherein one CH.sub.2 group is replaced by an oxygen atom and Cy is 1,4-cyclohexylene.
23. A compound of claim 22 which is
(a) r-1-cyano-1-ethyl-cis-4-(trans-4-ethylcyclohexyl)-cyclohexane,
(b) r-1-cyano-1-ethyl-cis-4-(trans-4-heptylcyclohexyl)-cyclohexane,
(c) r-1-cyano-1-propyl-cis-4-(trans-4-propylcyclohexyl)-cyclohexane,
(d) r-1-cyano-1-propyl-cis-4-(trans-4-butylcyclohexyl)-cyclohexane,
(e) r-1-cyano-1-propyl-cis-4-(trans-4-pentylcyclohexyl)-cyclohexane,
(f) r-1-cyano-1-propyl-cis-4-(trans-4-heptylcyclohexyl)-cyclohexane,
(g) r-1-cyano-1-isopropyl-cis-4-(trans-4-heptyl-cyclohexyl)cyclohexane,
(h) r-1-cyano-1-butyl-cis-4-(trans-4-propylcyclohexyl)-cyclohexane,
(i) r-1-cyano-1-butyl-cis-4-(trans-4-butylcyclohexyl)-cyclohexane,
(j) r-1-cyano-1-pentyl-cis-4-(trans-4-propylcyclohexyl)-cyclohexane,
(k) r-1-cyano-1-pentyl-cis-4-(trans-4-butylcyclohexyl)-cyclohexane,
(l) r-1-cyano-1-pentyl-cis-4-(trans-4-pentylcyclohexyl)-cyclohexane,
(m) r-1-cyano-1-pentyl-cis-4-(trans-4-heptylcyclohexyl)-cyclohexane,
(n) r-1-cyano-1-hexyl-cis-4-(trans-4-propylcyclohexyl)-cyclohexane,
(o) r-1-cyano-1-hexyl-cis-4-(trans-4-butylcyclohexyl)-cyclohexane,
(p) r-1-cyano-1-heptyl-cis-4-(trans-4-propylcyclohexyl)-cyclohexane,
(q) r-1-cyano-1-heptyl-cis-4-(trans-4-butylcyclohexyl)-cyclohexane,
(r) r-1-cyano-1-heptyl-cis-4-(trans-4-pentylcyclohexyl)-cyclohexane,
(s) r-1-cyano-1-octyl-cis-4-(trans-4-propylcyclohexyl)-cyclohexane,
(t) r-1-cyano-1-nonyl-cis-4-(trans-4-propylcyclohexyl)-cyclohexane,
(u) r-1-cyano-1-decyl-cis-4-(trans-4-propylcyclohexyl)-cyclohexane,
(v) r-1-cyano-1-ethoxymethyl-cis-4-(trans-4-pentylcyclohexyl)cyclohexane.
24. A compound of claim 7 of the formula ##STR7## wherein R.sup.1 is alkyl of 2-7 C atoms, A.sup.2 is 1,4-cyclohexylene or 1,4-phenylene and R.sup.2 is alkyl of 2-10 C atoms.
25. A compound of claim 24 which is
(a) trans-4-propylcyclohexyl 1-cyano-trans-4-pentyl-cyclohexane-r-1-carboxylate,
(b) trans-4-butylcyclohexyl 1-cyano-trans-4-pentyl-cyclohexane-r-1-carboxylate,
(c) trans-4-pentylcyclohexyl 1-cyano-trans-4-pentyl-cyclohexane-r-1-carboxylate,
(d) trans-4-hexylcyclohexyl 1-cyano-trans-4-pentyl-cyclohexane-r-1-carboxylate, or
(e) p-propylphenyl 1-cyano-trans-4-pentyl-cyclohexane-r-1-carboxylate.
26. A compound, of claim 1 of the formula
R.sup.1' --A--Z.sup.0 --(A.sup.1' --Z.sup.').sub.m --(A.sup.2').sub.n --R.sup.2'
wherein
R.sup.1' and R.sup.2' are each C.sub.1-10 -alkyl; C.sub.1-10 -alkyl wherein one or two non-adjacent CH.sub.2 groups are replaced by 0 atoms or --CH.dbd.CH--, the maximum number of C-atoms still being 15; F; Cl,; Br; CN; --COOR; --O--COR; or --C.tbd.C--R.sup.340 ,
A.sup.1' and A.sup.2' are each 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, 1,4-phenylene, pyridazine-3,6-diyl or pyrimidine-2,5-diyl, or one of the last three groups C-substituted by one or two of F, Cl, CH.sub.3, or CN,
A is 1,4-cyclohexylene substituted in the 1- or 4-position by CN,
Z.sup.0 and Z.sup.1' are each --CO--O--, --O--CO--, --CH.sub.2 --CH.sub.2 --, --OCH.sub.2, --CH.sub.2 --O--or a single bond,
R.sup.3' is alkyl of 1-7 C atoms,
R is alkyl of 1-10 C atoms and
m and n are each independently 1 or 2, and
wherein (m+n).gtoreq.3or, when Z.sup.0 is a single bond and Z.sup.1' is not a single bond, .gtoreq.2 and when m=2 or n=2, all groups A.sup.1' , A.sup.2' and Z.sup.1' which are present are identical or different.
27. A compound of claim 26 of the formula
R.sup.1' --A--Al.sup.1' --Z.sup.1' --A.sup.2' --R.sup.2'
R.sup.1' --A--(A.sup.1').sub.2 --A.sup.2' --R.sup.2'
R.sup.1' --A--Al.sup.1' --Z.sup.1' --(A.sup.2').sub.2 --R.sup.2'
R.sup.1' --A--(A.sup.1').sub.2 --Z.sup.1' --A.sup.2' --R.sup.2'
R.sup.1' --A--Z.sup.0 --(A.sup.1').sub.2 --A.sup.2' --R.sup.2'
R.sup.1' --A--Z.sup.0 --(A.sup.1').sub.2 --Z.sup.1' --A.sup.2' --R.sup.2'
R.sup.1' --A--(A.sup.1' --Z.sup.1').sub.2 --A.sup.2' --R.sup.2'
R.sup.1' --A--(A.sup.1').sub.2 --(A.sup.2').sub.2 --R.sup.2' or
R.sup.1' --A--(A.sup.1').sub.2 --Z.sup.1' --(A.sup.2').sub.2 --R.sup.2'
28. A compound, of claim 26 of the formula
R.sup.1' --A--Pyr-Z.sup.1' --Cy--R.sup.2'
R.sup.1' --A--Pyr--Z.sup.1' --Phe--R.sup.2'
R.sup.1' --A--Pyn--Z.sup.1' --Phe--R.sup.2'
R.sup.1' --A--Pyn--Z.sup.1' --Cy--R.sup.2'
R.sup.1' --A--Phe--Phe--Cy--R.sup.2'
R.sup.1' --A--Phe--Phe--Dio--R.sup.2'
R.sup.1' --A--Cy--Phe--Phe--R.sup.2'
R.sup.1' --A--Cy--Phe--Cy--R.sup.2'
R.sup.1' --A--Cy--Phe--Dio--R.sup.2'
R.sup.1' --A--Phe--Cy--Cy--R.sup.2'
R.sup.1' --A--Phe--Cy--Dio--R.sup.2'
R.sup.1' --A--Phe--Pyr--Cy--R.sup.2'
R.sup.1' --A--Phe--Pyn--Cy--R.sup.2'
R.sup.1' --A--Pyr--Phe--Cy--R.sup.2'
R.sup.1' --A--Pyn--Phe--Cy--R.sup.2'
R.sup.1' --A--Pyn--Phe--Dio--R.sup.2'
R.sup.1' --A--Phe--Z.sup.1' --Phe--R.sup.2'
R.sup.1' --A--Phe--Z.sup.1' --Cy--R.sup.2'
R.sup.1' --A--Cy--Z.sup.1' --Cy--R.sup.2'
R.sup.1' --A--Cy--Z.sup.1' --Phe--R.sup.2'
R.sup.1' --A--Pyr--Z.sup.1' --Phe--R.sup.2'
R.sup.1' --A--Pyr--Z.sup.1' --Cy--R.sup.2'
R.sup.1' --A--Cy--Z.sup.1' --Dio--R.sup.2'
R.sup.1' --A--Cy--Z.sup.1' --Pyr--R.sup.2'
R.sup.1' --A--Cy--Z.sup.1' --Pyn--R.sup.2'
R.sup.1' --A--Phe--Z.sup.1' --Dio--R.sup.2'
R.sup.1' --A--Phe--Z.sup.1' --Pyn--R.sup.2'
R.sup.1' --A--Dio--Z.sup.1' --Phe--R.sup.2'
R.sup.1' --A--Dio--Z.sup.1' --Cy--R.sup.2'
R.sup.1' --A--Phe--Phe--Z.sup.1' --Cy--R.sup.2'
R.sup.1' --A--Phe--Phe--Z.sup.1' --Dio--R.sup.2'
R.sup.1' --A--Phe--Phe--Z.sup.1' --Phe--R.sup.2'
R.sup.1' --A--Cy--Phe--Z.sup.1' --Cy--R.sup.2'
R.sup.1' --A--Cy--Phe--Z.sup.1' --Phe--R.sup.2'
R.sup.1' --A--Cy--Cy--Zhu 1'--Phe--R.sup.2'
R.sup.1' --A--Cy--Cy--Z.sup.1' --Cy--R.sup.2'
R.sup.1' --A--Cy--Phe--Z.sup.1' --Dio--R.sup.2'
R.sup.1' --A--Z.sup.0 --Phe--Phe--Cy--R.sup.2'
R.sup.1' --A--Z.sup.0 --Cy--Phe--Phe--R.sup.2'
R.sup.1' --A--Z.sup.0 --Cy--Phe--Cy--R.sup.2'
R.sup.1' --A--Z.sup.0 --Phe--Phe--Dio--R.sup.2'
R.sup.1' --A--Z.sup.0 --Cy--Cy--Phe--R.sup.2'
R.sup.1' --A--Z.sup.0 --Phe--Cy--Cy--R.sup.2'
R.sup.1' --A--Z.sup.0 --Dio--Cy--Phe--R.sup.2' or
R.sup.1' --A--Z.sup.0 --Phe--Cy--Dio--R.sup.2'
wherein Phe is 1,4-phenylene, Cy is 1,4-cyclohexylene, Dio is 1,3-dioxane-2,5-diyl, Pyn is pyridazine-3,6-diyl and Pyr is pyrimidine-2,5-diyl.
29. A compound of claim 1 of the formula
Alkyl--A.sup.1 --Z.sup.1 --A--Alkyl
Alkoxy--A.sup.1 --Z.sup.1 --A--Alkyl
Alkyl--Phe--Z.sup.1 --A--Alkyl
Alkoxy--Phe--Z.sup.1 --A--Alkyl
Alkyl--Phe--A--Alkyl
Alkoxy--Phe--A--Alkyl
Alkyl--Phe--CO--O--A--Alkyl
Alkoxy--Phe--CO--O--A--Alkyl
Alkyl--Phe--O--CO--A--Alkyl
Alkoxy--Phe--O--CO--A--Alkyl
Alkoxy--Phe--CH.sub.2 CH.sub.2 --A--Alkyl
Alkoxy--Phe--CH.sub.2 CH.sub.2 --A--Alkyl
Alkyl--Phe--Phe--CH.sub.2 CH.sub.2 --A--Alkyl
Alkoxy--Phe--Phe--CH.sub.2 CH.sub.2 --A--Alkyl
Alkyl--Phe--O--CH.sub.2 --A--Alkyl
Alkoxy--Phe--O--CH.sub.2 --A--Alkyl
Alkyl--Phe--CH.sub.2 --O--A--Alkyl
Alkoxy--Phe--CH.sub.2 --O--A--Alkyl
Alkyl--Cy--Zl--A--Alkyl
Alkyl--Cy--A--Alkyl
Alkyl--Cy--CO--O--A--Alkyl
Alkyl--Cy--O--CO--A--Alkyl
Alkyl--Cy--CH.sub.2 CH.sub.2 --A--Alkyl
Alkyl--Cy--O--CH.sub.2 --A--Alkyl
Alkyl--Cy--CH.sub.2 --O--A--Alkyl
Alkyl--Dio--A-Alkyl
Alkyl--Pyr--A--Alkyl
Alkoxy--Pyr--A--Alkyl
Alkyl--Pyn--A--Alkyl
Alkyl--Phe--Phe--A--Alkyl
Alkoxy--Phe--Phe--A--Alkyl
Alkyl--Phe--Cy--A--Alkyl
Alkoxy--Phe--Cy--A--Alkyl
Alkyl--Phe--A--Cy--Alkyl
Alkyl--Cy--Cy--A--Alkyl
Alkoxy--Cy--Cy--A--Alkyl
Alkyl--Cy--Phe--A--Alkyl
Alkyl--Cy--Cy--CO--O--A--Alkyl
Alkyl--Cy--Cy--O--CO--A--Alkyl
Alkyl--Dio--Phe--CO--O--A--Alkyl
Alkyl--Dio--Phe--O--CO--A--Alkyl
Alkyl--Cy--Phe--CH.sub.2 CH.sub.2 --A--Alkyl
Alkyl--Cy--Cy--CH.sub.2 CH.sub.2 --A--Alkyl
Alkyl--Dio--Phe--CH.sub.2 CH.sub.2 --A--Alkyl
Alkyl--Phe--Phe--CO--O--A--Alkyl
Alkoxy--Phe--Phe--CO--O--A--Alkyl
Alkyl--Phe--Phe--O--CO--A--Alkyl or
Alkoxy--Phe--Phe--O--CO--A--Alkyl
wherein Phe is 1,4-phenylene, Cy is 1,4-cyclohexylene, Dio is 1,3-dioxane-2,5-diyl, Pyn is pyridazine-3,6-diyl and Pyr is pyrimidine-2,5-diyl.
30. A phase of claim 26 wherein said cyclohexane derivative is of the formula
Alkyl--A--Phe--Phe--Cy--Alkyl
Alkyl--A--Phe--Phe--Dio--Alkyl
Alkyl--A--Phe--Phe--Dio--Alkoxy
Alkyl--A--Cy--Phe--Phe--Alkyl
Alkyl--A--Cy--Phe--Phe--Alkoxy
Alkyl--A--Cy--Phe--Phe--CN
Alkyl--A--Phe--CH.sub.2 CH.sub.2 --Phe--Alkyl
Alkyl--A--Phe--CH.sub.2 CH.sub.2 --Phe--Alkoxy
Alkyl--A--Phe--CH.sub.2 CH.sub.2 --Phe--CN
Alkyl--A--phe--CH.sub.2 CH.sub.2 --Cy--Alkyl
Alkyl--A--Cy--CH.sub.2 CH.sub.2 --Cy--Alkyl
Alkyl--A--Cy--CH.sub.2 CH.sub.2 --Phe--Alkyl
Alkyl--A--Cy--CH.sub.2 CH.sub.2 --Phe--Alkoxy
Alkyl--A--Phe--COO--Phe--CN
Alkyl--A--Phe--COO--Phe--Alkyl
Alkyl--A--Phe--COO--Phe--Alkoxy
Alkyl--A--Phe--COO--Phe--CN
Alkyl--A--Phe--OCO--Phe--Alkyl
Alkyl--A--Phe--OCO--Phe--Alkoxy
Alkyl--A--Phe--OCO--Phe--CN
Alkyl--A--Phe--COO--Cy--Alkyl
Alkyl--A--Phe--OCO--Cy--Alkyl
Alkyl--A--CH.sub.2 CH.sub.2 --Phe--Phe--Cy--Alkyl or
Alkyl--A--Phe--Phe--CH.sub.2 CH.sub.2 --Cy--Alkyl
wherein Phe is 1,4-phenylene, Cy is 1,4-cyclohexylene and Dio is 1,3-dioxane-2,5-diyl.
31. A compound of claim 26 of the formula ##STR8##
32. A compound of claim 26 of the formula ##STR9##
33. A compound of claim 1, wherein A is ##STR10## wherein the substituents in the 1- and 4-positions are in the trans-position relative to one another, while the CN group is in the position cis to the opposite group.

Priority Claims (3)

Number	Date	Country
3231707	Aug 1982	DEX
3320024	Jun 1983	DEX
3407013	Feb 1984	DEX

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation of application Ser. No. 705,811 filed Feb. 26, 1985 now abandoned, which is a continuation-in-part of U.S. Patents Application Ser. No. 526,927 of Aug. 26, 1983, now U.S. Pat. No. 4,510,069 and which disclosure is incorporated by reference herein. This invention relates to new compounds having valuable liquid crystalline properties. It is an object of this invention to provide new stable liquid crystal or mesogenic compounds which are suitable as components of liquid crystal phases. Upon further study of the specification and appended claims, further objects and advantages of this invention will become apparent to those skilled in the art. These objects have been achieved by providing cyclohexane derivatives of the formula I R.sup.1 and R.sup.2 are each H, an unsubstituted or substituted alkyl group with 1-15 C atoms, it also being possible for one or two non-adjacent CH.sub.2 groups to be replaced by at least one grouping from the group comprising --O--, --CO--, --O--CO--, --CO--O--, ----C.tbd.C--, --CH.dbd.CH--, --S--, --SO-- and --SO.sub.2 --, F, Cl, Br, CN or R.sup.3 --(A.sup.3).sub.p --Z.sup.2 --, A.sup.1 is --A--, --A.sup.4 --Z.sup.3 --A-- or --A--Z.sup.3 --A.sup.4 --, A is a 1,4-cyclohexylene group which is substituted in the 1- and/or 4-position by unsubstituted or substituted alkyl or fluorinated alkyl with in each case 1-5 C atoms, it also being possible for one or two non-adjacent CH.sub.2 groups to be replaced by one grouping from the group comprising --O--, --CO--, --O--CO--, --CO--O--, --C.tbd.C--, --S--, --SO-- and --SO.sub.2 --, or by F, Cl, Br, CN and/or --CHO, and which can carry 1 or 2 further substituents, A.sup.2, A.sup.3 in each case are 1,4-phenylene which is unsubstituted unsubstituted or substituted by one or two F and/or C1 atoms and/or CH.sub.3 groups and/or CN groups, it also being possible for one or two CH groups to be replaced by N atoms, 1,4-cyclohexylene, it also being possible for one or two non-adjacent CH.sub.2 groups to be replaced by O atoms. 1,4-cyclohexylene 1-enyl, 1,3-dithiane-2,5-diyl, piperidine-1,4-diyl, 1,4-bicyclo(2,2,2)-octylene, unsubstituted or CN-substituted decahydronaphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl or --A--, Z.sup.1, Z.sup.2 each are --CO--O--, --O--CO--, --OCH.sub.2 --, --CH.sub.2 --, and Z.sup.3 -CH.sub.2 CH.sub.2 --, substituted ethylene or a single bond, R.sup.3 is H, an unsubstituted or substituted alkyl group with 1-15 C atoms, it also being possible for one or two non-adjacent CH.sub.2 groups to be replaced by a grouping from the group comprising --O--, --CO--, --O--CO--, --CO--O--, --C.tbd.C--, --CH.dbd.CH--, --S--, --SO-- and --SO.sub.2 --, F, Cl, Br or CN and p is 1 or 2, For simplicity, in the following text Phe is an unsubstituted or substituted 1,4-phenylene group, Cy is a 1,4-cyclohexylene group, Dio is a 1,3-dioxane-2,5-diyl group, Dit is a 1,3-dithiane-2,5-diyl group, Bi is a bicyclo(2,2,2)-octylene group, Pip is a piperidine-1,4diyl group, Pyn is a pyridazine-3,6-diyl group and Pyr is a pyrimidine-2,5-diyl group. The compounds of the formula I can be used as components of liquid crystal phases, in particular for displays which are based on the principle of the twisted cell, the guest/host effect, the effect of deformation of aligned phases or the effect of dynamic scattering. It has been found that the compounds of the formula I are outstandingly suitable as components of liquid crystal phases. In particular, stable liquid crystal phases with highly negative dielectric anisotropy and thus a smaller threshold or control voltage of electrooptical effects, very low optical anisotropy and comparatively low viscosity can be prepared with the aid of these compounds. Surprisingly, it has been found that when compounds of the formula I are added to mixtures with positive dielectric anisotropy, even the addition of relatively large amounts (for example of 30%) only insignificantly increases the threshold voltage. At the same time, a completely unexpected substantial improvement in the steepness of the characteristic line of the mixture occurs, so that compounds of type I are particularly advantageously suitable substances for the preparation of liquid crystal mixtures with a steep characteristic line. They thus enable the development of highly multiplyable mixtures of very small optical anisotropy, with which a rotating cell, in particular, can be operated in the first transmission minimum in accordance with the Gooch-Tarry method. This results in a very small dependency of the contrast on the observation angle. By providing the compounds of the formula I, the range of liquid crystal substances which are suitable, from various technological viewpoints, for the preparation of nematic mixtures is also quite generally considerably increased. The compounds of the formula I have a wide range of application. Depending on the choice of the substituents, these compounds can be used as base materials from which liquid crystal phases are predominantly composed; however, it is also possible to add compounds of the formula I to liquid crystal base materials from other classes of compounds, for example in order to reduce the dielectric and/or optical anisotropy of such a dielectric. The compounds of the formula I are furthermore suitable as intermediates for the preparation of other substances which can be used as constituents of liquid crystal phases. The compounds of the formula I are colorless in the pure state and form liquid crystal mesophases in a temperature range which is advantageously located for electrooptical use. They are very stable towards chemicals, heat and light. The invention thus relates to the compounds of the formula I and to a process for their preparation, characterized in that a compound which otherwise corresponds to the formula I but contains one or more reducible groups and/or C-C bonds instead of H atoms is treated with a reducing agent, or in that a compound of the formula HX (wherein X is F, Cl, Br or CN) is added onto a compound which otherwise corresponds to the formula I but, instead of the radical A, contains a 1-cyclohexene-1,4-diyl group which can carry 1 or 2 further F, Cl or. Br atoms and/or CN groups, or in that, to prepare esters of the formula I (wherein R.sup.1 and/or R.sup.2 are an alkyl group in which one or two CH.sub.2 groups are replaced by a carboxyl group, and/or wherein Z.sup.1 and/or Z.sup.2 and/or Z.sup.3 are --CO--O-- or O----CO--), a corresponding carboxylic acid or one of its reactive derivatives is reacted with a corresponding alcohol or one of its reactive derivatives, or in that, to prepare dioxane derivatives derivatives of the formula I (wherein A.sup.2 and/or A.sup.3 and/or A.sup.4 are 1,3-dioxane-2,5-diyl or 1,3-dithiane-2,5-diyl), a corresponding aldehyde or one of its reactive derivatives is reacted with a corresponding diol, or in that, to prepare nitriles of the formula I (wherein R.sup.1 and/or R.sup.2 denote CN and/or wherein A and/or A.sub.2 and/or A.sup.3 and/or A.sup.4 are substituted by at least one CN group), a corresponding carboxylic acid amide is dehydrated or a corresponding carboxylic acid halide is reacted with sulfamide, or in that, to prepare nitriles of the formula I (wherein A is a 1,4-cyclohexylene group which is substituted in the 1- or 4-position by CN), a corresponding acetonitrile is reacted with a corresponding 3-substituted 1,5-dihalogenopentane or 1,5-pentanediol or one of their reactive derivatives, or in that, to prepare nitriles of the formula I (wherein A is 1,4-cyclohexylene group which is substituted in the 1- or 4position by CN and can additionally carry 1 or 2 further substituents), a corresponding 4-substituted cyclohexanecarbonitrile is reacted with a corresponding halogen compound or hydroxy compound or one of their reactive derivatives, or in that, to prepare compounds of the formula I (wherein A is a 1,4-cyclohexylene group which is substituted in the 1- or 4-position by an alkoxycarbonyl group with 1 to 4 C atoms and which can additionally carry 1 or 2 further substituents), a corresponding 4-substituted cyclohexanecarboxylic acid ester is reacted with a corresponding halogen compound or hydroxy compound or one of their reactive derivatives, or in that, to prepare aldehydes of the formula I (wherein A is a 1,4-cyclohexylene group which is substituted in the 1- or 4-position by --CHO and which can additionally carry 1 or 2 further substituents), a corresponding nitrile of the formula I is reduced, or in that, to prepare compounds of the formula I (wherein A is a 1,4-cyclohexylene group which is substituted in the 1- or 4-position by --CH.sub.3 and which can additionally carry 1 or 2 further substituents), a corresponding aldehyde is reduced, or in that, to prepare compounds of the formula I (wherein A is a 1,4-cyclohexylene group which is substituted in the 1- or 4-position by F and can additionally carry 1 or 2 further substituents), a corresponding hydroxy or halogen compound is treated with a fluorinating agent, or in that, to prepare ethers of the formula I (wherein R.sup.1 and/or R.sup.2 are an alkyl group, in which one or two CH.sub.2 groups are replaced by O atoms, and/or Z.sup.1 and/or Z.sup.2 and/or Z.sup.3 are an --OCH.sub.2 -- or --CH.sub.2 O--group), a corresponding hydroxy compound is etherified, or in that, to prepare compounds of the formula I wherein R.sup.1 and/or R.sup.2 are an alkyl group, in which one or two CH.sub.2 groups are replaced by --SO-- or --SO.sub.2 --, a corresponding compound wherein R.sup.1 and/or R.sup.2 are SR or SOR is oxidized, or in that, to prepare compounds of the formula I (wherein A is a 1,4-cyclohexylene group which is substituted in the 1- or 4-position by an alkyl group, wherein one or two non-adjacent CH.sub.2 groups are replaced by --SO-- or --SO.sub.2 --, and which can additionally carry 1 or 2 further substituents), a corresponding thio or sulfinyl compound is oxidized, or in that, to prepare compounds of the formula I which contain CF.sub.3 groups, a corresponding carboxylic acid is reacted with SF.sub.4, and/or in that, if appropriate, a chlorine or bromine compound of the formula I (wherein R.sup.1 and/or R.sup.2 denote Cl or Br and/or wherein A is substituted by at least one chlorine or bromine atom and/or A.sup.2 and/or A.sup.3 and/or A.sup.4 are substituted by at least one chlorine atom) is reacted with a cyanide, and/or in that, if appropriate, a base of the formula I is converted into one of its acid addition salts by treatment with an acid, or in that, if appropriate, a compound of the formula I is liberated from one of its acid addition salts by treatment with a base. The invention furthermore relates to the use of compounds of the formula I as components of liquid crystal phases. The invention also relates to liquid crystal phases containing at least one compound of the formula I, and to liquid crystal display elements, in particular electrooptical display elements, containing such phases. Above and below, R.sup.1, R.sup.2, R.sup.3, A.sup.1, A.sup.2, A.sup.3, A.sup.4, A, Z.sup.1, Z.sup.2, Z.sup.3, X and p have the meaning given, unless expressly indicated otherwise. The compounds of the formula I accordingly include, in particular, compounds of the part formulae I1 and I2 (with two rings), I3-I20 (with 3 rings), I21-I71 (with 4 rings) and I72-I94 (with 5 rings): Particularly preferred smaller groups of compounds are those of the formulae I001 to I002:______________________________________R.sup.1 --Phe--Z.sup.1 --A--R.sup.2 I001R.sup.1 --Cy--Z.sup.1 --A--R.sup.2 I002R.sup.1 --Dio--Z.sup.1 --A--R.sup.2 I003R.sup.1 --Pip--Z.sup.1 --A--R.sup.2 I004R.sup.1 --Bi--Z.sup.1 --A--R.sup.2 I005R.sup.1 --Pyr--Z.sup.1 --A--R.sup.2 I006R.sup.1 --Phe--Z.sup.1 --A--Z.sup.2 --Phe--R.sup.2 I007R.sup.1 --Dio--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2 I008R.sup.1 --Cy--Z.sup.1 --A--Z.sup.2 --Phe--R.sup.2 I009R.sup.1 --Cy--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2 I010R.sup.1 --Phe--Phe--Z.sup.1 --A--R.sup.2 I011R.sup.1 --Phe--Cy--Z.sup.1 --A--R.sup.2 I012R.sup.1 --Cy--Phe--Z.sup.1 --A--R.sup.2 I013R.sup.1 --Cy--Cy--Z.sup.1 --A--R.sup.2 I014R.sup.1 --Phe--Phe--Z.sup.1 --A--Z.sup.2 --Phe--R.sup.2 I015R.sup.1 --Phe--Phe--Z.sup. 1 --A--Z.sup.2 --Cy--R.sup.2 I016R.sup.1 --Phe--Cy--Z.sup.1 --A--Z.sup.2 --Phe--R.sup.2 I017R.sup.1 --Phe--Cy--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2 I018R.sup.1 --Cy--Phe--Z.sup.1 --A--Z.sup.2 --Phe--R.sup.2 I019R.sup.1 --Cy--Phe--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2 I020R.sup.1 --Cy--Cy--Z.sup.1 --A--Z.sup.2 --Phe--R I021R.sup.1 --Cy--Cy--Z.sup.1 --A--Z.sup.2 --Cy--R.sup.2 I022______________________________________ Compounds which are also preferred are the cyclohexane derivatives of the formula II R.sup.1' and R.sup.2' are each H, an alkyl group with 1-10 C atoms, it also being possible for one or two non-adjacent CH.sub.2 groups to be replaced by O atoms, F, Cl, Br, CN, --COOR, --O--COR, SOR, SO.sub.2 R or --C.tbd.C--R.sup.3', A.sup.1' and A.sup.2' are each 1,4-phenylene, 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, 1,3-dithiane-2,5-diyl, piperidine-1,4-diyl, 1,4-bicyclo(2,2,2)-octylene, pyridazine-3,6-diyl or pyrimidine-2,5-diyl groups which are unsubstituted or substituted (according to the above) by one or two F and/or Cl atoms and/or CH.sub.3 groups and/or CN groups, or A, A is a 1,4-cyclohexylene group which is substituted in the 1- and/or 4-position by unsubstituted or substituted alkyl or fluorinated alkyl with in each case 1-5 C atoms, it also being possible for one or two non-adjacent CH.sub.2 groups to be replaced by a grouping from the group comprising --O--, --CO--, --O--CO--, --CO--O--, --C.tbd.C--, --S--, --SO-- and --SO.sub.2 --, or by F, Cl, Br, CN and/or --CHO, and which can carry 1 or 2 further substituents, Z.sup.0 and Z.sup.1' are each --CO--O--, --O--CO--, --CH.sub.2 CH.sub.2 --, --OCH.sub.2 --, --CH.sub.2 O-- or a single bond, R.sup.3' is H, CN or an alkyl group with 1-7 C atoms, R is an alkyl group with 1-10 C atoms and m and n are each independently of one another 1 or 2, and The invention thus furthermore relates to the compounds of the formula II and to a process for their preparation, characterized in that a compound which otherwise corresponds to the formula II but contains one or more reducible groups and/or C-C bonds instead of H atoms is treated with a reducing agent, or in that a compound of the formula HX (wherein X is F, Cl, Br or CN) is added onto a compound which otherwise corresponds to the formula II but, instead of the radical A, contains a 1-cyclohexene-1,4-diyl group which can carry 1 or 2 further F, Cl or Br atoms and/or CN groups, or in that, to prepare esters of the formula II (wherein R.sup.1' and/or R.sup.2' are --OCOR and/or --COOR and/or wherein Z.sup.0 and/or Z.sup.1' are --CO--O-- or --O--CO--), a corresponding carboxylic acid or one of its reactive derivatives is reacted with a corresponding alcohol or one of its reactive derivatives, or in that, to prepare dioxane derivatives or dithiane derivatives of the formula II (wherein A.sup.1' and/or A.sup.2' are 1,3-dioxane-2,5-diyl or 1,3-dithiane-2,5-diyl), a corresponding aldehyde or one of its reactive derivatives is reacted with a corresponding diol or dithiol, or in that, to prepare nitriles of the formula II (wherein R.sup.1' and/or R.sup.2' are CN and/or wherein A and/or A.sup.1' and/or A.sup.2' are substituted by at least one CN group), a corresponding carboxylic acid amide is dehydrated or a corresponding carboxylic acid halide is reacted with sulfamide, or in that, to prepare nitriles of the formula II (wherein A is a 1,4-cyclohexylene group which is substituted in the 1- or 4-position by CN), an acetonitrile of the formula III E.sup.1 is X.sup.1 is Cl, Br, I, OH or a reactive esterified OH group, E.sup.2 is Q.sup.1 is Q.sup.3 is a 1,4-cyclohexylene group which is unsubstituted or mono- or di-substituted by F and/or CN, Q.sup.2 is The invention furthermore relates to the use of the compounds of the formula II as components of liquid crystal phases. The invention also relates to liquid crystal phases containing at least one compound of the formula II and liquid crystal display elements, in particular electrooptical display elements, containing such phases. Above and below, R.sup.1', R.sup.2', R.sup.3', R, A.sup.1', A.sup.2', A, Z.sup.0, Z.sup.1', m, n, X.sup.1, E.sup.1, E.sup.2, Q.sup.1, Q.sup.2 and Q.sup.3 have the meaning given, unless expressly indicated otherwise. The compounds of the formula II include, in particular, compounds of the part formula IIa (with three rings), IIb-IIg (with four rings) and IIh and IIi (with five rings):______________________________________R.sup.1' --A--A.sup.1' --Z.sup.1' --A.sup.2' --R.sup.2' IIaR.sup.1' --A--(A.sup.1').sub.2 --A.sup.2' --R.sup.2' IIbR.sup.1' --A--A.sup.1' --Z.sup.1' --(A.sup.2').sub.2 --R.sup.2' IIcR.sup.1' --A--(A.sup.1').sub.2 --Z.sup.1' --A.sup.2' --R.sup.2' IIdR.sup.1' --A--Z.sup.0 --(A.sup.I').sub.2 --A.sup.2' --R.sup.2' IIeR.sup.1' --A--Z.sup.0 --(A.sup.1').sub.2 --Z.sup.1' --A.sup.2' --R.sup.2' IIfR.sup.1' --A--(A.sup.1' --Z.sup.1').sub.2 --A.sup.2' --R.sup.1' IIgR.sup.1' --A--(A.sup.1').sub.2 --(A.sup.2').sub.2 --R.sup.2' IIhR.sup.1' --A--(A.sup.1').sub.2 --Z.sup.1' --(A.sup.2').sub.2 IIi.sup.2'______________________________________ Of these, those of the part formulae IIa, IIb, IIc, IId and IIe are preferred. The preferred compounds of the part formula IIa include those of the part formulae IIaI to IIa25:______________________________________R.sup.1' --A--Phe--Z.sup.1' --Phe--R.sup.2' IIa1R.sup.1' --A--Phe--Z.sup.1' --Cy--R.sup.2' IIa2R.sup.1' --A--Cy--Z.sup.1' --Cy--R.sup.2' IIa3R.sup.1' --A--Cy--Z.sup.1' --Phe--R.sup.2' IIa4R.sup.1' --A--Pyr--Z.sup.1' --Phe--R.sup.2' IIa5R.sup.1' --A--Pyr--Z.sup.1' --Cy--R.sup.2' IIa6R.sup.1' --A--Cy--Z.sup.1' --Dio--R.sup.2' IIa7R.sup.1' --A--Cy--Z.sup.1' --Dit--R.sup.2' IIa8R.sup.1' --A--Cy--Z.sup.1' --Pyr--R.sup.2' IIa9R.sup.1' --A--Cy--Z.sup.1' --Pyn--R.sup.2' IIa10R.sup.1' --A--Cy--Z.sup.1 --Bi--R.sup.2' IIa11R.sup.1' --A--Phe--Z.sup.1' --Dio--R.sup.2' IIa12R.sup.1' --A--Phe-- Z.sup.1' --Dit--R.sup.2' IIa13R.sup.1' --A--Phe--Z.sup.1' --Bi--R.sup.2 IIa14R.sup.1' --A--Phe--Z.sup.1' --Pyn--R.sup.2' IIa15R.sup.1' --A--Dio--Z.sup.1' --Phe--R.sup.2' IIa16R.sup.1' --A--Dio--Z.sup.1' --Cy--R.sup.2' IIa17R.sup.1' --A--Dit--Z.sup.1' --Phe--R.sup.2' IIa18R.sup.1' --A--Dit--Z.sup.1' --Cy--R.sup.2' IIa19R.sup.1' --A--Bi--Z.sup.1' --Fhe--R.sup.2' IIa20R.sup.1' --A--Bi--Z.sup.1' --Cy--R.sup.2' IIa21R.sup.1' --A--Pyr--Z.sup.1' --Cy--R.sup.2' IIa22R.sup.1' --A--Pyr--Z.sup.1' --Phe--R.sup.2' IIa23R.sup.1' --A--Pyn--Z.sup.1' --Phe--R.sup.2' IIa24R.sup.1' --A--Pyn--Z.sup.1' --Cy--R.sup.2' IIa25______________________________________ Of these, those of the formulae IIa1 to IIa4, in particular IIa1 and IIa2, are particularly preferred. In the compounds of part formula IIa, Z.sup.1' and Z.sup.0 are preferably --CO--O--, --O--CO-- or --CH.sub.2 CH.sub.2 --. The preferred compounds of part formula IIb include those of the part formulae IIb1 to IIb16:______________________________________R.sup.1' --A--Phe--Phe--Cy--R.sup.2' IIb1R.sup.1' --A--Phe--Phe--Dio--R.sup.2' IIb2R.sup.1' --A--Phe--Phe--A--R.sup.2' IIb3R.sup.1' --A--Cy--Phe--Phe--R.sup.2' IIb4R.sup.1' --A--Cy--Phe--Cy--R.sup.2' IIb5R.sup.1' --A--Cy--Phe--Dio--R.sup.2' IIb6R.sup.1' --A--Phe--Phe--Dit--R.sup.2 IIb7R.sup.1' --A--Phe--Phe--Bi--R.sup.2' IIb8R.sup.1' --A--Phe--Cy--Cy--R.sup.2' IIb9R.sup.1' --A--Phe--Cy--Dio--R.sup.2' IIb10R.sup.1' --A--Phe--Cy--Dit--R.sup.2' IIb11R.sup.1' --A--Phe--Pyr--Cy--R.sup.2' lIb12R.sup.1' --A--Phe--Pyn--Cy--R.sup.2' IIb13R.sup.1' --A--Pyr--Phe--Cy--R.sup.2' IIb14R.sup.1' --A--Pyn--Phe--Cy--R.sup.2' IIb15R.sup.1' --A--Pyn--Phe--Dio--R.sup.2' IIb16______________________________________ Of these, those of the formulae IIb1 to IIb4 are particularly preferred. Compounds of the formula IIb wherein at least one of the rings A.sup.1' is substituted, preferably by F, are furthermore especially preferred. The preferred compounds of the part formula IIc include those wherein A.sup.1' and A.sup.2' are chosen from the series Cy, Phe and Dio and Z.sup.1' is --CO--O--, --O--CO-- or --CH.sub.2 CH.sub.2 --. The preferred compounds of the part formula IId include those of the part formulae IId1 to IId8:______________________________________R.sup.1' --A--Phe--Phe--Z.sup.1' --Cy--R.sup.2' IId1R.sup.1' --A--Phe--Phe--Z.sup.1' --Dio--R.sup.2' IId2R.sup.1' --A--Phe--Phe--Z.sup.1' --Phe--R.sup.2' IId3R.sup.1' --A--Cy--Phe--Z.sup.1' --Cy--R.sup.2' IId4R.sup.1' --A--Cy--Phe--Z.sup.1' --Phe--R.sup.2' IId5R.sup.1' --A--Cy--Cy--Z.sup.1' --Phe--R.sup.2' IId6R.sup.1' --A--Cy--Cy--Z.sup.1' --Cy--R.sup.2' IId7R.sup.1' --A--Cy--Phe--Z.sup.1' --Dio--R.sup.2' IId8.______________________________________ The preferred compounds of the part formula IIe include those of the part formulae IIe1 to IIe8:______________________________________R.sup.1' --A--Z.sup.0 --Phe--Phe--Cy--R.sup.2' IIe1R.sup.1' --A--Z.sup.0 --Cy--Phe--Phe--R.sup.2' IIe2R.sup.1' --A--Z.sup.0 --Cy--Phe--Cy--R.sup.2' IIe3R.sup.1' --A--Z.sup.0 --Phe--Phe--Dio--R.sup.2' IIe4R.sup.1' --A--Z.sup.0 --Cy--Cy--Phe--R.sup.2' IIe5R.sup.1' --A--Z.sup.0 --Phe--Cy--Cy--R.sup.2 IIe6R.sup.1' --A--Z.sup.0 --Dio--Cy--Phe--R.sup.2 IIe7R.sup.1' --A--Z.sup.0 --Phe--Cy--Dio--R.sup.2 IIe8.______________________________________ Of these, those of the formulae IIe1, IIe4 and IIe6 are particularly preferred. Compounds of the formulae IIe1 to IIe8 wherein at least one of the rings A.sup.1' is substituted, preferably by F, and/or those wherein Z.sup.0 is --CO--O--, --O--CO-- or --CH.sub.2 CH.sub.2 --, particularly preferably --CH.sub.2 CH.sub.2 --, are furthermore especially preferred. In the compounds of the formulae I and II above and below, a substituted alkyl group or substituted ethylene is an alkyl group or --CH.sub.2 CH.sub.2 -- (ethylene) group which is monosubstituted or polysubstituted, on different C atoms, by halogen, preferably fluorine or chlorine, or CN. Preferably there will be only one halo or cyano substituent on each C-atom. In the compounds of the formulae I and II above and below, R.sup.1 and R.sup.2, or R.sup.1' and R.sup.2', are preferably alkyl, and furthermore alkoxy or another oxaalkyl group. Compounds of the formulae I and II wherein one of the radicals R.sup.1 and R.sup.2, or R.sup.1' and R.sup.2', is H, CN, F, Cl, Br, SOR or SO.sub.2 R, in particular H, CN, F or Cl, are furthermore preferred. A.sup.2, A.sup.3 and A.sup.4, or A.sup.1' and A.sup.2', are preferably independently of one another Cy, Dio or Phe, and furthermore preferably Dit, Pyr or Pip; the compound of the formula I or II preferably contains not more than one of the radicals Dio, Dit, Pip, Bi, Pyn or Pyr. A is preferably a 1--X--1,4-cyclohexylene group which carries no further substituents and wherein X is alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy with in each case 1-5 C atoms, or F, Cl, Br or CN. Particularly preferred is CN. X is preferably a CN, CH.sub.3, CH.sub.3 O or CF.sub.3 group. A is furthermore preferably a 1-X-1,4-cyclohexylene group which carries no further substituents and wherein X is --CHO, --COO--alkyl, --S--alkyl, --SO--alkyl, --SO.sub.2 --alkyl, wherein alkyl is a straight-chain alkyl group with 1-4 C atoms. Z.sup.1, Z.sup.2 and Z.sup.3, or Z.sup.0' and Z.sup.1', are preferably independently of one another single bonds or --CH.sub.2 CH.sub.2 --, --CO--O-- or --O--CO-- groups. Further substituents of A are preferably CH.sub.3, F or CN. but in general all A substituents disclosed for the 1- and/or 4-positions are possible further substituents. n and p are preferably 1. Substituted ethylene is preferably --CH.sub.2 CHX--, wherein X has one of the meanings indicated above. F substitution on the alkyl groups includes one F-atom to perfluorination. X.sup.1 is preferably Cl or Br, but also I, OH or reactively esterified OH, such as alkylsulphonyloxy with, in particular, 1-6 C atoms (for example methylsulfonyloxy) or arylsulfonyloxy with, in particular, 6-10 C atoms (for example phenyl-, p-tolyl- or naphthyl-sulfonyloxy). If R.sup.1' and/or R.sup.2', or R.sup.1 and/or R.sup.2 and/or R.sup.3, are alkyl radicals in which one ("alkoxy" or "oxaalkyl") or two ("alkoxyalkoxy" or "dioxaalkyl") non-adjacent CH.sub.2 groups can be replaced by O atoms, they can be straight-chain or branched. Preferably, they are straight-chain and have 2, 3, 4, 5, 6 or 7 C atoms, and are accordingly preferably ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, 2-oxapropyl (=methoxymethyl), 2- (=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3- or 4-oxapentyl, 2-, 3-, 4- or 5-oxahexyl or 2-, 3-, 4-, 5- or 6-oxaheptyl, and furthermore methyl, octyl, nonyl, decyl, methoxy, octoxy, nonoxy, decoxy, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl, 1,3-dioxabutyl (=methoxymethoxy), 1,3-, 1,4- or 2,4-dioxapentyl, 1,3-, 1,4-, 1,5-, 2,4-, 2,5- or 3,5-dioxahexyl or 1,3-, 1,4-, 1,5-, 1,6-, 2,4-, 2,5 -, 2,6-, 3,5-, 3,6- or 4,6-dioxaheptyl. Compounds of the formulae I and II with branched end group substituents R.sup.1, R.sup.2 and/or R.sup.3 or R.sup.1' and/or R.sup.2' can occasionally be of importance because of a better solubility in the usual liquid crystal base materials, but in particular as chiral doping substances, if they are optically active. Branched groups of this type as a rule contain not more than one chain branching. Preferred branched radicals are isopropyl, 2-butyl (=1-methyloropyl), isobutyl (=2-methylpropyl), 2-methylbutyl, isopentyl (=3-methylbutyl), 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl, 2-propylpentyl, isopropoxy, 2-methylpropoxy, 2-methylbutoxy, 3-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethylhexoxy, 1-methylhexoxy, 1-methylheptoxy, 2-oxa-3-methylbutyl and 3-oxa-4-methylpentyl. In the case of compounds with branched end group substituents, the formulae I and II include both the optical antipodes and the racemates as well as mixtures thereof. In the radicals R and X, the alkyl groups and/or alkoxy groups are likewise preferably straight-chain and are, in particular, methyl or ethyl, and furthermore propyl, butyl or pentyl, and X is also methoxy or ethoxy, and furthermore propoxy, butoxy or pentoxy. Of the compounds of the formulae I and II and their sub-formulae, those in which at least one of the radicals contained therein has one of the preferred meanings mentioned are preferred. Particularly preferred smaller groups of compounds are those of the formulae VIII 1-56 (corresponding to formula I) and VIII 57-81 (corresponding to formula II):______________________________________Alkyl--A.sup.1 --Z.sup.1 --A--Alkyl VIII 1Alkoxy--A.sup.1 --Z.sup.1 --A--Alkyl VIII 2Alkyl--Phe--Z.sup.1 --A--Alkyl VIII 3Alkoxy--Phe--Z.sup.1 --A--Alkyl VIII 4Alkyl--Phe--A--Alkyl VIII 5Alkoxy--Phe--A--Alkyl VIII 6Alkyl--Phe--CO--O--A--Alkyl VIII 7Alkoxy--Phe--CO--O--A--Alkyl VIII 8Alkyl--Phe--O--CO--A--Alkyl VIII 9Alkoxy--Phe--O--CO--A--Alkyl VIII 10Alkyl--Phe--CH.sub.2 CH.sub.2 --A--Alkyl VIII 11Alkoxy--Phe--CH.sub.2 CH.sub.2 --A--Alkyl VIII 12Alkyl--Phe--Phe--CH.sub.2 CH.sub.2 --A--Alkyl VIII 13Alkoxy--Phe--Phe--CH.sub.2 CH.sub.2 --A--Alkyl VIII 14Alkyl--Phe--O--CH.sub.2--A--Alkyl VIII 15Alkoxy--Phe--O--CH.sub.2 --A--Alkyl VIII 16Alkyl--Phe--CH.sub.2 --O--A--Alkyl VIII 17Alkoxy--Phe--CH.sub.2 --O--A--Alkyl VIII 18Alkyl--Cy--Z.sup.1 --A--Alkyl VIII 19Alkyl--Cy--A--Alkyl VIII 20Alkyl--Cy--CO--O--A--Alkyl VIII 21Alkyl--Cy--O--CO-- A--Alkyl VIII 22Alkyl--Cy--CH.sub.2 CH.sub.2 --A--Alkyl VIII 23Alkyl--Cy--O--CH.sub.2 --A--Alkyl VIII 24Alkyl--Cy--CH.sub.2 --O--A--Alkyl VIII 25Alkyl--Dio--A--Alkyl VIII 26Alkyl--Dit--A--Alkyl VIII 27Alkyl--Pip--A--Alkyl VIII 28Alkyl--Pyr--A--Alkyl VIII 29Alkoxy--Pry--A--Alkyl VIII 30Alkyl--Pyn--A--Alkyl VIII 3lAlkyl--Phe--Phe--A--Alkyl VIII 32Alkoxy--Phe--Phe--A--Alkyl VIII 33Alkyl--Phe--Cy--A--Alkyl VIII 34Alkoxy--Phe--Cy--A--Alkyl VIIl 35Alkyl--Phe--A--Cy--Alkyl VIII 36Alkyl--Cy--Cy--A--Alkyl VIII 37Alkoxy--Cy--Cy--A--Alkyl VIII 38Alkyl--Cy--Phe--A--Alkyl VIII 39AIkyI--Cy--A--Cy--Alkyl VIII 40Alkyl--Cy--A--Cy--Alkoxy VIII 41Alkyl--Cy--Phe--O--CO--A--Alkyl VIII 42Alkyl--Cy--Cy--CO--O--A--Alkyl VIII 43Alkyl--Cy--Cy--O--CO--A--Alkyl VIII 44Alkyl--Dio--Phe--CO--O--A--Alkyl VIII 45Alkyl--Dio--Phe--O--CO--A--Alkyl VIII 46Alkyl--Dit--Phe--CO--O--A--Alkyl VIII 47Alkyl--Dit--Phe--O--CO-- A--Alkyl VIII 48Alkyl--Cy--Phe--CH.sub.2 CH.sub.2 --A--Alkyl VIII 49Alkyl--Cy--CY--CH.sub.2 CH.sub.2 --A--Alkyl VIII 50Alkyl--Dio--Phe--CH.sub.2 CH.sub.2 --A--Alkyl VIII 51Alkyl--Dit--Phe--CH.sub.2 CH.sub.2 --A--Alkyl VIII 52Alkyl--Phe--Phe--CO--O--A--Alkyl VIII 53Alkoxy--Phe--Phe--CO--O--A--Alkyl VIII 54Alkyl--Phe--Phe--O--CO--A--Alkyl VIII 55Alkoxy--Phe--Phe--O--CO--A--Alkyl VIII 56Alkyl--A--Phe--Phe--C--Alkyl VIII 57Alkyl--A--Phe--Phe--Dio--Alkyl VIII 58Alkyl--A--Phe--Phe--Dio--Alkoxy VIII 59Alkyl--A--Phe--Phe--A--Alkyl VIII 60Alkyl--A--Cy--Phe--Phe--Alkyl VIII 6lAlkyl--A--Cy--Phe--Phe--Alkoxy VIII 62Alkyl--A--Cy--Phe--Phe--CN VIII 63Alkyl--A--Phe--CH.sub.2 CH.sub.2 --Phe--Alkyl VIII 64Alkyl--A--Phe--CH.sub.2 CH.sub.2 --Phe--Alkoxy VIII 65Alkyl--A--Phe--CH.sub.2 CH.sub.2 --Phe--CN VIII 66Alkyl--A--Phe--CH.sub.2 CH.sub.2 --Cy--Alkyl VIII 67Alkyl--A--Cy--CH.sub.2 CH.sub.2 -- Cy--Alkyl VIII 68Alkyl--A--Cy--CH.sub.2 CH.sub.2 --Phe--Alkyl VIII 69Alkyl--A--Cy--CH.sub.2 CH.sub.2 --Phe--Alkoxy VIII 70Alkyl--A--Cy--CH.sub.2 CH.sub.2 --Phe--CN VIII 7lAlkyl--A--Phe--COO--Phe--Alkyl VIII 72Alkyl--A--Phe--COO--Phe--Alkoxy VIII 73Alkyl--A--Phe--COO--Phe--CN VIII 74Alkyl--A--Phe--OCO--Phe--Alkyl VIII 75Alkyl--A--Phe--OCO--Phe--Alkoxy VIII 76Alkyl--A--Phe--OCO--Phe--CN VIII 77Alkyl--A--Phe--COO--Cy--Alkyl VIII 78Alkyl--A--Phe--OCO--Cy--Alkyl VIII 79Alkyl--A--CH.sub.2 CH.sub.2 --Phe--Phe--Cy--Alkyl VIII 80Alkyl--A--Phe--Phe--CH.sub.2 CH.sub.2 --Cy--Alkyl VIII 81______________________________________ In the compounds VIII 1-81 Alkyl and Alkoxy are preferably straight-chain alkyl and alkoxy groups having in each case 2 to 7 carbon atoms. VIII 32, VIII 33, VIII 36, VIII 37, VIII 39, VIII 40 and VIII 41 are particularly preferred. In the compounds of the above formulae VIII 1-81, in particular VIII 32, 33, 57, 58, 59, 60, 61, 62 and 63, Phe can also be a 1,4-phenylene group which is laterally substituted in the 2- or 3-position, in particular by F. In the compounds of the abovementioned formulae, the group A contains a substituent X, which can be in the 1- or 4-position. Thus, for example, the compounds of the formula II include those of the following part formulae II' and II" ##STR1## (wherein the cyclohexane ring can additionally carry a further substituent X in the opposite position (4- or 1-position) of the cyclohexene ring and 1 or 2 further F, Cl or Br atoms and/or CN groups). In this context, particularly preferred compounds of the above formulae I are furthermore those in which the radical A is in each case ##STR2## wherein alkyl in each case is a straight-chain alkyl group with 1-4 C atoms. Those stereoisomers here in which the groups R.sup.1' -- and --Z.sup.o --(A.sup.1' --Z.sup.1').sub.m --(A.sup.2').sub.n --R.sup.2' are in the trans-position relative to one another, while the substituent X is in the cis-position relative to the opposite group are preferred. Thus, for example, the following stereoisomers of the compounds of the formula II' are preferred: ##STR3## In general, those compounds of the formula I and II in which, in the ring A, the substituents in the 1- and 4-position with the longest chain length are in the trans-position are preferred. If mixtures of stereoisomers are obtained in the synthesis, the preferred isomers can be isolated by separation processes which are known per se, for example chromatography or crystallization (if appropriate in the presence of urea). Those of the abovementioned formulae which contain one or more of the groups Dio, Dit, Pip and/or Pyr include in each case the two possible 2,5-position isomers (Dio, Dit or Pyr) or 1,4-position isomers (Pip). Particularly preferred compounds of the formula I are those wherein R.sup.1 and R.sup.2 are each straight-chain or at most singly branched alkyl groups with 1-10 C atoms, it also being possible for one or two CH.sub.2 groups to be replaced by O atoms or --CH.dbd.CH--, or F, Cl, Br, CN or --O--COR and A.sup.1, A.sup.2, A, Z.sup.0, Z.sup.1, R, m and n have the meaning given in the case of formula I. Alkenyl groups in the compounds of the formuIa I (or II) are preferabIy straight-chain trans-alkenyl groups of the formula, ##STR4## wherein n2 is 0 or 2, preferably 2, and n1 is 1 to 5. Compounds of the formula I (wherein one of the radicals R.sup.1, R.sup.2 and R.sup.3 is F, Cl, Br or CN, in particular CN) or of the formula II (wherein one of the radicals R.sup.1', R.sup.2' and R.sup.3' is F, Cl, Br or CN, in particular CN) wherein A in each case is a 1,4-cyclohexylene group which is substituted in the 1-position and/or 4-position by unsubstituted or substituted alkyl or fluorinated alkyl, each having 1 to 5 carbon atoms, wherein one or two CH.sub.2 groups which are not adjacent to one another may furthermore be replaced with a grouping from the group comprising --O--, --CO--, --O--CO--, -CO--O--, --C--C--, --S--, --SO-- and --SO.sub.2 --, and/or by --CHO, being compounds which exhibit positive dielectric anisotropy, are particularly suitable as components of liquid-crystalline phases having an overall positive dielectric anisotropy. In this context, A is preferably a 1,4-cyclohexylene group (formula (5) or (6)) which is substituted in the 1- position or 4-position by methyl. Particularly preferred compounds exhibiting positive dielectric anisotropy are those of the formula I, wherein A.sup.1 --A.sup.4 --Z.sup.3 --A-- or --A--Z.sup.3 --A.sup.4 -- and/or A.sup.2 and, if appropriate, A.sup.3 or A.sup.4 are each 1,4-cyclohexylene. Particularly preferred compounds are those of the formulae Ia to Ie,______________________________________R.sup.1 --Cy--Phe--CN IaR.sup.1 --A--Cy--COO--Phe--CN IbR.sup.1 --A--Phe--COO--Phe--CN IcR.sup.2 --Cy--A--CN IdR.sup.2 --Cy--Cy--A--CN Ie______________________________________ The liquid-crystalline phases according to the invention, containing these positive compounds of the formulae I and/or II, preferably contain at least one further component selected from the compounds of the following formulae: The compounds of the formulae I and II are prepared by methods which are known per se, such as are described in the literature (for example in the standard works, such as Houben-Weyl, Methoden der Organischer Chemie (Methods of Organic Chemistry), Georg-Thieme-Verlag, Stuttgart), and in particular under reaction conditions which are known and suitable for the reactions mentioned. It is also possible to utilize variants which are known per se and are not mentioned in more detail here. If desired, the starting substances can also be formed in situ, by a process in which they are not isolated from the reaction mixture but are immediately reacted further to give the compounds of the formula I or II. Thus, the compounds of the formula I can be prepared by reducing a compound which otherwise corresponds to the formula I but contains one or more reducible groups and/or C-C bonds instead of H atoms. Preferred possible reducible groups are carbonyl groups, in particular keto groups, and furthermore, for example, free or esterified hydroxyl groups or aromatically bonded halogen atoms. Preferred starting substances for the reduction correspond to the formula I, but can contain a cyclohexene ring or cyclohexanone ring instead of a cyclohexane ring and/or a --CH.dbd.CH-- group instead of a --CH.sub.2 CH.sub.2 -- group, and/or a --CO-- group instead of a --CH.sub.2 -- group, and/or a free or functionally modified (for example in the form of its p-toluenesulfonate) OH group instead of an H atom. The reduction can be carried out, for example, by catalytic hydrogenation at temperatures between about 0.degree. and about 200.degree. and under pressures between about 1 bar and 200 bar in an inert solvent, for example an alcohol, such as methanol, ethanol or isopropanol, an ether, such as tetrahydrofuran (THF) or dioxane, an ester, such as ethyl acetate, a carboxylic acid, such as acetic acid, or a hydrocarbon, such as cyclohexane. Suitable catalysts are advantageously noble metals, such as Pt or Pd, which can be used in the form of oxides (for example PtO.sub.2 or PdO) on a support (for example Pd on charcoal, calcium carbonate or strontium carbonate), or in finely divided form. Ketones can also be reduced by the methods of Clemmensen (with zinc, zinc amalgam or tin and hydrochloric acid, advantageously in aqueous-alcohol solution or in a heterogeneous phase system with water/toluene at temperatures between about 80.degree. and 120.degree.) or Wolff-Kishner (with hydrazine, advantageously in the presence of alkali, such as KOH or NaOH, in a high-boiling solvent, such as diethylene glycol or triethylene glycol, at temperatures between about 100.degree. and 200.degree.), to give the corresponding compounds of the formula I containing alkyl groups and/or --CH.sub.2 CH.sub.2 -- bridges. Reductions with complex hydrides are furthermore possible. For example, arylsulfonyloxy groups can be removed by reduction with LiAlH.sub.4, in particular p-toluenesulfonyloxymethyl groups can be reduced to methyl groups, advantageously in an inert solvent, such as diethyl ether or THF, at temperatures between about 0.degree. and 100.degree. C. Double bonds can be hydrogenated with NaBH.sub.4 or tributyl-tin hydride in methanol (even in the presence of CN groups!); thus, for example, the corresponding cyclohexane derivatives are formed from 1-cyanocyclohexene derivatives. Aldehydes of the formula I (wherein A denotes a 1,4-cyclohexylene group which is substituted in the 1-or 4-position by --CHO and which can additionally carry one or two further substituents) can also be obtained in an analogous manner by reduction of corresponding nitriles of the formula I. Compounds of the formula I can furthermore be obtained by adding a compound of the formula HX (hydrogen fluoride, chloride, bromide or cyanide) onto a corresponding cyclohexene derivative (which corresponds to the formula I but contains, instead of the radical A, a 1-cyclohexene-1,4-diyl group which can carry 1 or 2 further F, Cl or Br atoms and/or CN groups). This addition reaction is effected, for example, in the presence of an inert solvent, for example a halogenated hydrocarbon, such as CH.sub.2 Cl.sub.2 or CHCl.sub.3, a nitrile, such as acetonitrile, or an amide, such as dimethylformamide (DMF) at temperatures between about -10.degree. and +150.degree. and under pressures between about 1 and 100 bar. It may be advantageous to add catalysts, for example addition of HCN can be catalyzed by adding palladium bis-[2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis-(diphenylphosphino)-butane]. Esters of the formula I (R.sup.1 and/or R.sup.2 =--O--COR and/or --COOR and/or Z.sup.0 and/or Z.sup.1 =--CO--O-- or --O--CO--) can also be obtained by esterification of corresponding carboxylic acids, for example of the formulae R--COOH, R.sup.1 --A--COOH, R.sup.1 --A--Z.sup.0 --(A.sup.1).sub.m --COOH or R.sup.1 --A--Z.sup.0 --(A.sup.1).sub.m --A.sup.2 --COOH (or their reactive derivatives) with alcohols or phenols of the formulae R.sup.1 --A--Z.sup.0 --(A.sup.1 --Z.sup.1).sub.m --(A.sup.2).sub.n --OH, R.sup.2 --(A.sup.2).sub.n --(Z.sup.1 --A.sup.1).sub.m --Z.sup.0 --A--OH, R.sup.2 --(A.sup.2).sub.n --(Z.sup.1 --A.sup.1).sub.m --OH, R.sup.2 --(A.sup.2).sub.n --OH or R.sup.2 --(A.sup.2).sub.n-1 --OH or their reactive derivatives). Particularly suitable reactive derivatives of the carboxylic acids mentioned are the acid halides, above all the chlorides and bromides, and furthermore the anhydrides, for example also mixed anhydrides of the formulae R.sup.1 --A--CO--O--COCH.sub.3, R.sup.1 --A--Z.sup.O --(A.sup.1 --Z.sup.1).sub.m --CO--O--COCH.sub.3 or R.sup.1 --A--Z.sup.0 --(A.sup.1 --Z.sup.1).sub.m --(A.sup.2).sub.n --CO--O--COCH.sub.3, azides or esters, in particular alkyl esters with 1-4 C atoms in the alkyl group. The corresponding metal alcoholates or phenolates of the formula --R.sup.1 --A--Z.sup.0 --(A.sup.1 --Z.sup.1).sub.m --(A.sup.2).sub.n --OM, R.sup.2 --(A.sup.2).sub.n --(Z.sup.1 --A.sup.1).sub.m --Z.sup.0 --A--OM, R.sup.2 --(A.sup.2).sub.n --(Z.sup.1 A.sup.1).sub.m --OM, R.sup.2 --(A.sup.2).sub.n --OM or R.sup.2 --(A.sup.2).sub.n-1 --OM, wherein M is one equivalent of a metal, preferably an alkali metal, such as Na or K, are particularly suitable reactive derivatives of the alcohols and phenols mentioned. The esterification is advantageously carried out in the presence of an inert solvent. Particularly suitable solvents are ethers, such as diethyl ether, di-n-butyl ether, THF, dioxane or anisole, ketones, such as acetone, butanone or cyclohexanone, amides, such as DMF or phosphoric acid hexamethyltriamide, hydrocarbons, such as benzene, toluene or xylene, halogenohydrocarbons, such as carbon tetrachloride or tetrachloroethylene, and sulfoxides, such as dimethylsulfoxide or sulfolane. Water-immiscible solvents can at the same time advantageously be used for removal of the water formed during the esterification by azeotropic distillation. An excess of an organic base, for example pyridine, quinoline or triethylamine, may occasionally also be used as the solvent for the esterification. The esterification can also be carried out in the absence of a solvent, for example by simply heating the components in the presence of sodium acetate. The reaction temperature is usually between -50.degree. and +250.degree., preferably between -20.degree. and +80.degree.. At these temperatures, the esterification reactions are as a rule ended after 15 minutes to 48 hours. In detail, the reaction conditions for the esterification largely depend on the nature of the starting substances used. Thus, a free carboxylic acid is as a rule reacted with a free alcohol or phenol in the presence of a strong acid, for example a mineral acid, such as hydrochloric acid or sulfuric acid. A preferred reaction procedure is the reaction of an acid anhydride or, in particular, an acid chloride with an alcohol, preferably in a basic medium, important bases being, in particular, alkali metal hydroxides, such as sodium hydroxide or potassium hydroxide, alkali metal carbonates or bicarbonates, such as sodium carbonate, sodium bicarbonate, potassium carbonate or potassium bicarbonate, alkali metal acetates, such as sodium acetate or potassium acetate, alkaline earth metal hydroxides, such as calcium hydroxide, or organic bases, such as triethylamine, pyridine, lutidine, collidine or quinoline. Another preferred embodiment of the esterification comprises first converting the alcohol or the phenol into the sodium alcoholate or phenolate or potassium alcoholate or phenolate, for example by treatment with ethanolic sodium hydroxide solution or potassium hydroxide solution, isolating this product and suspending it in acetone or diethyl ether, together with sodium bicarbonate or potassium carbonate, with stirring, and adding a solution of the acid chloride or anhydride in diethyl ether, acetone or DMF to this suspension, advantageously at temperatures between about -25.degree. and +20.degree.. Dioxane derivatives and dithiane derivatives of the formula I (wherein one of the groups A.sup.1 and/or A.sup.2 is a 1,3-dioxane-2,5-diyl group or 1,3-dithiane-2,5-diyl group) are advantageously prepared by reacting a corresponding aldehyde, for example of the formula R.sup.1 --A--Z.sup.0 --(A.sup.1 --Z.sup.1).sub.m --A.sup.2 --CHO, R.sup.1 --A--Z.sup.0 --(A.sup.1).sub.m --CHO or O.dbd.CH--R.sup.2 (or one of its reactive derivatives), with a corresponding 1,3-diol, for example of the formulae (HOCH.sub.2).sub.2 CH--(A.sup.2).sub.n-2 --R.sup.2, (HOCH.sub.2).sub.2 CH--(A.sup.2).sub.n-1 --R.sup.2 or R.sup.1 --A--Z.sup.0 --(A.sup.1 --Z.sup.1).sub.m --(A.sup.2).sub.n-1 --CH(CH.sub.2 OH).sub.2 (or one of its reactive derivatives), or a corresponding 1,3-dithiol, preferably in the presence of an inert solvent, such as benzene or toluene, and/or a catalyst, for example a strong acid, such as sulfuric acid or benzene-or p-toluene-sulfonic acid, at temperatures between about 20.degree. and about 150.degree., preferably between 80.degree. and 120.degree.. Suitable reactive derivatives of the starting substances are, above all, acetals, for example of the formulae R.sup.1 --A--Z.sup.0 --(A.sup.1 --Z.sup.1).sub.m --A.sup.2 --CH(OR.sup.4).sub.2, R.sup.1 --A--Z.sup.0 --(A.sup.1).sub.m --CH(OR.sup.4).sub.2, (R.sup.4 O).sub.2 --R.sup.2, R.sup.1 --A--Z.sup.0 --(A.sup.1 --Z.sup.1).sub.m --A.sub.2 --CH(CH.sub.2 O).sub.2 CH--R.sup.5 or R.sup.1 --A--Z.sup.o --(A.sup.1).sub.m --CH(CH.sub.2 O).sub.2 CHR.sup.5, wherein R.sup.4 is alkyl with 1-4 C atoms, or two radicals R.sup.4 together are also alkylene with 2 or 3 C atoms, and R.sup.5 is H, alkyl with 1-4 C atoms or phenyl. The aldehydes and 1,3-diols or 1,3-dithiols mentioned and their reactive derivatives are known in some cases, and some of them can be prepared without difficulty by standard methods of organic chemistry from compounds which are known from the literature. For example, the aldehydes can be obtained by oxidation of corresponding alcohols or by reduction of corresponding carboxylic acids or their derivatives, the diols can be obtained by reduction of corresponding diesters and the dithiols can be obtained by reacting corresponding dihalides with NaSH. To prepare nitriles of the formula I (wherein R.sup.1 and/or R.sup.2 are CN and/or wherein A and/or A.sup.1 and/or A.sup.2 are substituted by at least one CN group), corresponding acid amides, for example those in which the radical X is replaced by a CONH.sub.2 group, can be dehydrated. The amides can be obtained, for example, from corresponding esters or acid halides by reaction with ammonia. Examples of suitable dehydrating agents are inorganic acid chlorides, such as SOCl.sub.2, PCl.sub.3, PCl.sub.5, POCl.sub.3, SO.sub.2 Cl.sub.2 or COCl.sub.2, and furthermore P.sub.2 O.sub.5, P.sub.2 S.sub.5, AlCl.sub.3 (for example as a double compound with NaCl) and aromatic sulfonic acids and sulfonic acid halides. The reaction can be carried out in the presence or absence of an inert solvent at temperatures between about 0.degree. and 150.degree.; examples of possible solvents are bases, such as pyridine or triethylamine, aromatic hydrocarbons, such as benzene, toluene or xylene, or amides, such as DMF. To prepare the abovementioned nitriles of the formula I, it is also possible to react corresponding acid halides, preferably the chlorides, with sulfamide, advantageously in an inert solvent, such as tetramethylene sulfone, at temperatures between about 80.degree. and 150.degree., preferably at 120.degree.. After customary working up, the nitriles can be isolated directly. Nitriles of the formula I wherein A is a 1,4-cyclohexylene group which is substituted by CN can also be obtained by alkylation of acetonitriles of the formula II with 1,5-di-X.sup.1 -pentane derivatives of the formula III. The acetonitriles can be obtained, for example, from corresponding halides of the formula E.sup.1 --CH.sub.2 X.sup.1 and metal cyanides, and the compounds III can be obtained by reduction of corresponding glutaric acid diesters to give the corresponding diols (III, X.sup.1 .dbd.OH) and, if appropriate, reaction thereof with inorganic halides, such as SOCl.sub.2, HBr or HI. The acetonitrile is advantageously first converted into the corresponding carbanion with a strong base, such as NaH, NaNH.sub.2, lithium diisopropylamide, piperidide or 2,5-diisopropyl-piperidide or K tert.-butylate, preferably in an inert solvent, for example a hydrocarbon, such as toluene, an ether, such as THF or dioxane, an amide, such as DMF, a sulfoxide, such as dimethyl sulfoxide, or a mixture of such solvents. After adding III (wherein X.sup.1 is other than OH), the mixture is advantageously kept at temperatures between 0.degree. and 150.degree. for 0.5 to 16 hours. In contrast, reaction of II with III (X.sup.1 .dbd.OH) is advantageously effected in the presence of azodicarboxylic acid esters/triphenylphosphine in THF at temperatures between about -30.degree. and +30.degree.. In a completely analogous manner, nitriles or esters of the formula 1 wherein A is a 1,4-cyclohexylene group which is substituted in the 1- or 4-position by CN or --COO-alkyl and which additionally can be substituted by 1-2 F atoms and/or CN groups can be obtained by reacting a nitrile of the formula IV or a corresponding ester compound with a halide of the formula V. The nitriles of the formula IV can be obtained, for example, from corresponding amides of the formula Q.sup.1 --A.sup.3 CONH.sub.2 by dehydration, the esters can be obtained by hydrolysis of the corresponding nitriles and esterification, and the halides of the formula V can be obtained from corresponding alcohols of the formula Q.sup.2 --OH. Fluorine compounds of the formula I wherein A is a 1,4-cyclohexylene group which is substituted in the 1- or 4-position by F and which can additionally carry 1 or 2 further substituents can be obtained by treatment of the corresponding hydroxy compounds or bromine or chlorine compounds with a fluorinating agent. Fluorinating agents which can be used are all the compounds known for these exchange reactions, for example diethylaminesulfur trifluoride (J. Org. Chem. 40 (5), 574-8 (1975)). The hydroxy, bromine and chlorine compounds can be obtained, for example, from the corresponding cyclohexene compounds by adding on H.sub.2 O, HBr or HCl. Ethers of the formula I (wherein R.sup.1 and/or R.sup.2 are an alkyl group, in which one or two CH.sub.2 groups are replaced by O atoms, and/or wherein Z.sup.0 and/or Z.sup.1 and/or Z.sup.2 are an --OCH.sub.2 -- or a --CH.sub.2 O-- group) can be obtained by etherification of corresponding hydroxy compounds, preferably corresponding phenols, the hydroxy compound advantageously first being converted into a corresponding metal derivative, for example into the corresponding alkali metal alcoholate or alkali metal phenolate by treatment with NaH, NaNH.sub.2, NaOH, KOH, Na.sub.2 CO.sub.3 or K.sub.2 CO.sub.3. This product can then be reacted with the corresponding alkyl halide, sulfonate or dialkyl sulfate, advantageously in an inert solvent, such as acetone, 1,2-dimethoxyethane, DMF or dimethylsulfoxide, or an excess of aqueous or aqueous-alcoholic NaOH or KOH, at temperatures between about 20.degree. and 100.degree.. To prepare compounds of the formula I wherein R.sup.1 and/or R.sup.2 are SOR or SO.sub.2 R, corresponding compounds wherein R.sup.1 and/or R.sup.2 are SR or SOR can be oxidized. Depending on the chosen reagent and the conditions applied, the starting substances are oxidized to the corresponding sulfoxides or to the corresponding sulfones of the formula I; the reactions are carried out by methods which are known per se from the literature, and the reaction conditions can easily be found in detail in the literature. If the sulfoxides are to be obtained, the corresponding thioethers are oxidized, for example, with hydrogen peroxide, peracids, Cr(VI) compounds, such as chromic acid, nitric acid, nitrous gases, N.sub.2 O.sub.3, halogens, such as chlorine, hypochlorites, KMnO.sub.4, N-bromosuccinimide, 1-chlorobenzotriazole, Ce(IV) compounds, such as (NH.sub.4).sub.2 Ce(NO.sub.3).sub.6, or negatively substituted aromatic diazonium salts, such as o- or p-nitrophenyldiazonium chloride, or electrolytically under relatively mild conditions and at relatively low temperatures (about -80.degree. to +100.degree.). In contrast, if the sulfones are to be obtained, the same oxidizing agents are used under more severe conditions and/or in excess and as a rule at higher temperatures. The usual inert solvents can be present or absent in these reactions. Examples of suitable inert solvents are water, aqueous mineral acids, aqueous alkali metal hydroxide solutions, lower alcohols, such as methanol or ethanol, esters, such as ethyl acetate, ketones, such as acetone, lower carboxylic acids, such as acetic acid, nitriles, such as acetonitrile, hydrocarbons, such as benzene, or chlorinated hydrocarbons, such as chloroform or CCl.sub.4. A preferred oxidizing agent is 30% strength aqueous hydrogen peroxide. This leads to the sulfoxides if the calculated amount is used in solvents such as acetic acid, acetone, ethanol or aqueous sodium hydroxide solution at temperatures between -20.degree. and 100.degree., and in excess at higher temperatures, preferably in acetic acid or in a mixture of acetic acid and acetic anhydride, leads to the sulfones. Another preferred oxidizing agent is 3-chloroperbenzoic acid. This as a rule leads to the sulfoxides if the calculated amount is used in solvents such as halogenohydrocarbons at temperatures below 0.degree., and in excess at temperatures between 0.degree. and room temperature leads to the sulfones. Another possibility of preparing the sulfoxides comprises treating the thioethers with chlorine, for example in moist benzene or in acetic acid. The dichlorine compounds intermediately formed are very easily converted into the sulfoxides by hydrolysis. The thioethers are prepared by methods which are known per se, such as are described in the literature (for example in the standard works, such as Houben-Weyl, Methoden der Organischen Chemie (Methods of Organic Chemistry), Georg-Thieme-Verlag, Stuttgart), and in particular under reaction conditions which are known and suitable for the reactions mentioned. The thioethers are preferably obtained by treating corresponding halogen compounds, wherein halogen is chlorine, bromine or iodine, with salts of corresponding mercaptans. These halogen compounds are either known, or they can be prepared without difficulty by methods which are known per se, analogously to known compounds. Thus, for example, p-substituted halogenobenzene derivatives are accessible by halogenation of the corresponding benzene derivatives. 4-Substituted cyclohexyl halides can be obtained, for example, by reduction of the corresponding 4-substituted cyclohexanones to the 4-substituted cyclohexanols and subsequent substitution by halogen. In principle all methods which are known for the compounds which carry other substituents instead of the halogen can be applied in the synthesis of the halogen compounds. The expert can deduce the required synthesis variants by routine methods. To prepare compounds of the formula I wherein A is a 1,4-cyclohexylene group which is substituted in the 1- or 4-position by an alkyl group with 1-5 C atoms, in which one or two non-adjacent CH.sub.2 groups are replaced by --S--, --SO-- or --SO.sub.2 --, methods analogous to those for the preparation of the compounds with sulfur-containing groups R.sup.1, R.sup.2 and/or R.sup.3 can be used. To prepare compounds of the formula I which contain CF.sub.3 groups, corresponding carboxylic acids, which can in turn be obtained, for example, by hydrolysis of corresponding nitriles, can be reacted with SF.sub.4, advantageously with an excess of SF.sub.4, under pressure in the absence or in the presence of an inert solvent, such as cyclohexane or methylene chloride, at temperatures between about 70.degree. and 200.degree.. The reaction times vary between about 2 hours and about 4 days. To prepare nitriles of the formula I (wherein R.sup.1 and/or R.sup.2 are CN and/or wherein A and/or A.sup.1 and/or A.sup.2 are substituted by at least one CN group), it is also possible to react corresponding chlorine or bromine compounds of the formula I (wherein R.sup.1 and/or R.sup.2 are Cl or Br and/or wherein A is substituted by at least one Cl or Br atom and/or A.sup.1 and/or A.sup.2 are substituted by at least one chlorine atom) with a cyanide, advantageously with a metal cyanide, such as NaCN, KCN or Cu.sub.2 (CN).sub.2, for example in the presence of pyridine, in an inert solvent, such as DMF or N-methylpyrrolidone, at temperatures between 20.degree. and 200.degree.. A base of the formula I can be converted with an acid into the associated acid addition salt. For this reaction it is possible to use inorganic acids, for example sulfuric acid, nitric acid, hydrogen halide acids, such as hydrochloric acid or hydrobromic acid, phosphoric acids, such as orthophosphoric acid, or sulfamic acid, and furthermore organic acids, in particular aliphatic, alicyclic, araliphatic, aromatic or heterocyclic monobasic or polybasic carboxylic, sulfonic or sulfuric acids, for example formic acid, acetic acid, propionic acid, pivalic acid, diethylacetic acid, malonic acid, succinic acid, pimelic acid, fumaric acid, maleic acid, lactic acid, tartaric acid, malic acid, benzoic acid, salicylic acid, 2- or 3-phenylpropionic acid, citric acid, gluconic acid, ascorbic acid, nicotinic acid, isonicotinic acid, methane- or ethane-sulfonic acid, ethanedisulfonic acid, 2-hydroxyethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalene-mono- and -di-sulfonic acids and laurylsulfuric acid. Conversely, it is possible to liberate the base of the formula I from an acid addition salt of a compound of the formula I by treatment with a base, for example with a strong inorganic based such as KOH or NaOH. The salts of this invention are useful in particular for preparation of the compounds of formulae I and II by routine procedures. The compounds of the formula II can be prepared in a manner corresponding to that for the formula I, by analogous processes. For example, esters of the formula II (R.sup.1' and/or R.sup.2' =--O--COR and/or --COOR and/or Z.sup.0 and/or Z.sup.1' =--CO--O-- or --O--CO--) can be obtained by esterification of corresponding carboxylic acids, for example of the formulae R--COOH, R.sup.1' --A--COOH, R.sup.1' --A--Z.sup.0 --(A.sup.1').sub.m --COOH or R.sup.1' --A--Z.sup.0 --(A.sup.1').sub.m --A.sup.2' --COOH (or their reactive derivatives) with alcohols or phenols of the formulae R.sup.1' --A--Z.sup.0 --(A.sup.1' --Z.sup.1').sub.m --(A.sup.2').sub.n --OH, R.sup.2' --(A.sup.2').sub.n --(Z.sup.1' --A.sup.1').sub.m --Z.sup.0 --A--OH, R.sup.2' --(A.sup.2').sub.n --(Z.sup.1' --A.sup.1').sub.m --OH, R.sup.2' --(A.sup.2').sub.n --OH or R.sup.2' --(A.sup.2').sub. n-1 --OH (or their reactive derivatives). Particularly suitable reactive derivatives of the carboxylic acids mentioned are the acid halides, above all the chlorides and bromides, and furthermore the anhydrides, for example also mixed anhydrides of the formulae R.sup.1' --A--CO--O--COCH.sub.3, R.sup.1' --A--Z.sup.0 --(A.sup.1' --Z.sup.1').sub.m --CO--O--COCH.sub.3 or R.sup.1' --A--Z.sup.0 --(A.sup.1' --Z.sup.1').sub.m --(A.sup.2').sub.n --CO--O--COCH.sub.3, azides or esters, in particular alkyl esters with 1-4 C atoms in the alkyl group. Particularly suitable reactive derivatives of the alcohols and phenols mentioned are the corresponding metal alcoholates or phenolates of the formulae R.sup.1' --A--Z.sup.0 --(A.sup.1' --Z.sup.1').sub.m --(A.sup.2').sub.n --OM, R.sup.2' --(A.sup.2').sub.n --(Z.sup.1' --A.sup.1').sub.m --Z.sup.0 --A--OM, R.sup.2' --(A.sup.2').sub.n --(Z.sup.1' --A.sup.1').sub.m --OM, R.sup.2' --(A.sup.2').sub.n --OM or R.sup.2' --(A.sup.2').sub.n-1 --OM, wherein M is one equivalent of a metal, preferably an alkali metal, such as Na or K. For example, dioxane derivatives or dithiane derivatives of the formula II (wherein one of the groups A.sup.1' and/or A.sup.2' is a 1,3-dioxane-2,5-diyl group or 1,3-dithiane-2,5-diyl group) can advantageously be prepared by reacting a corresponding aldehyde, for example of the formula R.sup.1' --A--Z.sup.0 --(A.sup.1' --Z.sup.1').sub.m --A.sup.2' --CHO, R.sup.1' --A--Z.sup.0 --(A.sup.1').sub.m --CHO or O.dbd.CH--R.sup.2' (or one of its reactive derivatives) with a corresponding 1,3-diol, for example of the formula (HOCH.sub.2).sub.2 --CH--(A.sup.2').sub.n-2 --R.sup.2', (HOCH.sub.2).sub.2 CH--(A.sup.2').sub.n-1 --R.sup.2' or R.sup.1' --A--Z.sup.0 --(A.sup.1' --Z.sup.1').sub.m --(A.sup.2').sub.n-1 --CH(CH.sub.2 OH).sub.2 (or one of its reactive derivatives) or a corresponding 1,3-dithiol (or one of its reactive derivatives), preferably in the presence of an inert solvent, such as benzene or toluene, and/or a catalyst, for example a strong acid, such as sulfuric acid or benzene- or p-toluenesulfonic acid, at temperatures between about 20.degree. and about 150.degree., preferably between 80.degree. and 120.degree.. Suitable reactive derivatives of the starting substances are, above all, acetals, for example of the formulae R.sup.1' --A--Z.sup.0 --(A.sup.1' --Z.sup.1').sub.m --A.sup.2' --CH(OR.sup.4).sub.2, R.sup.1' --A--Z.sup.0 --(A.sup.1').sub.m --CH(OR.sup.4).sub.2, (R.sup.4 O).sub.2 --R.sup.2', R.sup.1' --A--Z.sup.0 --(A.sup.1' --Z.sup.1').sub.m --A.sup.2' --CH(CH.sub.2 O).sub.2 CH--R.sup.5 or R.sup.1' --A--Z.sup.0 --(A.sup.1').sub.m --CH(CH.sub.2 O).sub.2 CHR.sup.5, wherein R.sup.4 is alkyl with 1-4 C atoms, or two radicals R.sup.4 together are also alkylene with 2 or 3 C atoms, and R.sup.5 is H, alkyl with 1-4 C atoms or phenyl. Nitriles of the formula II wherein A is a 1,4-cyclohexylene group which is substituted by CN can also be obtained by alkylation of acetonitriles of the formula II with 1,5-di-X.sup.1 -pentane derivatives of the formula III. The acetonitriles can be obtained, for example, from corresponding halides of the formula E.sup.1 --CH.sub.2 X.sup.1 and metal cyanides, and the compounds III can be obtained by reduction of corresponding glutaric acid diesters to give the corresponding diols (III, X.sup.1 .dbd.OH) and, if appropriate, reaction thereof with inorganic halides, such as SOCl.sub.2, HBr or HI. The acetonitrile is advantageously first converted into the corresponding carbanion with a strong base, such as NaH, NaNH.sub.2, lithium diisopropylamide, piperidide or 2,5-diisopropyl-piperidide or K tert.-butylate, preferably in an inert solvent, for example a hydrocarbon, such as toluene, an ether, such as THF or dioxane, an amide, such as DMF, a sulfoxide, such as dimethyl sulfoxide, or a mixture of such solvents. After addition of III (wherein X.sup.1 is other than OH), the mixture is advantageously kept at temperatures between 0.degree. and 150.degree. for 0.5 to 16 hours. In contrast, reaction of II with III (X.sup.1 .dbd.OH) is advantageously effected in the presence of azodicarboxylic acid esters/triphenylphosphine in THF at temperatures between about -30.degree. and +30.degree.. In a completely analogous manner, nitriles of the formula II wherein A is a 1,4-cyclohexylene group which is substituted in the 1- or 4-position by CN and which can additionally be substituted by 1 or 2 F atoms and/or CN groups can be obtained by reacting a nitrile of the formula IV with a halide of the formula V. The nitriles of the formula IV can be obtained, for example, from corresponding amides of the formula Q.sup.1 --A.sup.3' CONH.sub.2 by dehydration, and the halides of the formula V can be obtained from corresponding alcohols of the formula Q.sup.2 --OH. Preferred intermediates for the preparation of the compounds of the formulae I and II according to the invention are the cyclohexanones of the formulae (A) and (B) ##STR5## wherein Q' is an alkyl group with 3-15 C atoms, it also being possible for one or two non-adjacent CH.sub.2 groups to be replaced by a grouping from the group comprising --O--, --CO--, --S--, --SO-- and --SO.sub.2 --, Q" is COOR.sup.0, OR.sup.0, SR.sup.0, SOR.sup.0, SO.sub.2 R.sup.0, R.sup.0, CF.sub.3, CCl.sub.3, CHF.sub.2, CN, CHO, F, Cl or Br and R.sup.0 is an alkyl group with 1-3 C atoms, and reactive derivatives thereof. Particularly preferred intermediates are those compounds of the formulae (A) and (B) wherein Q' is a straight-chain alkyl group with 4-9 C atoms and Q" is --CN, --CHO, --CF.sub.3, --CH.sub.3, OCH.sub.3 --, --SCH.sub.3, --SOCH.sub.3, --SO.sub.2 CH.sub.3, --COOCH.sub.3 or F, in particular --CN, --CH.sub.3 or F. The compounds of the formulae (A) and (B) are prepared by methods which are known per se, such as are described in the literature (for example in the standard works, such as Houben-Weyl, Methoden der Organischen Chemie (Methods of Organic Chemistry), Georg-Thieme-Verlag, Stuttgart), and in particular under reaction conditions which are known and suitable for the reactions mentioned. It is also possible to utilize the variants which are known per se and are not mentioned here in more detail. The compounds of the formulae (A) and (B) can be converted, for example, into ester derivatives of the formulae I and II by reduction of the carbonyl group and subsequent esterification. Ether derivatives of the formulae I and II can be obtained by etherification of the alcohols obtained from (A) and (B) by reduction. A large number of compounds of the formulae I and II can be obtained by Grignard reaction with the cyclohexanones of the formulae (A) and (B) and subsequent reduction. Wittig reaction with 2-substituted 1-bromoethane derivatives/triphenylphosphine and subsequent hydrogenation gives a large number of compounds of the formulae I and II with --CH.sub.2 CH.sub.2 -- groups between two ring structures. The liquid crystal phases according to the invention comprise 2 to 15, preferably 3 to 12, components, at least one of which is a compound of the formula I and/or II. The other constituents are preferably chosen from the nematic or nematogenic substances, in particular the known substances from the classes of azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, phenyl- or cyclohexyl-benzoates, phenyl or cyclohexyl cyclohexanecarboxylates, phenylcyclohexanes, cyclohexylbiphenyls, cyclohexylcyclohexanes, cyclohexylnaphthalenes, 1,4-biscyclohexylbenzenes, 4,4'-bis-cyclohexylbiphenyls, phenyl-or cyclohexyl-pyrimidines, phenyl- or cyclohexyl-dioxanes, phenyl- or cyclohexyl-1,3-dithianes, 1,2-diphenylethanes, 1,2-dicyclohexylethanes, 1-phenyl-2-cyclohexylethanes, optionally halogenated stilbenes, benzyl phenyl ethers, tolanes and substituted cinnamic acids. Phases according to the invention which, besides at least one compound of the formula I, contain at least one compound of the formula II are furthermore preferred. The most important compounds which are suitable as constituents of such liquid crystal phases can be characterized by the formula Ix Y is halogen, preferably chlorine, or --CN and R.sup.6 and R.sup.7 are alkyl, alkoxy, alkanoyloxy or alkoxycarbonyloxy with up to 18, preferably up to 8, carbon atoms, or one of these radicals is also CN, NC, NO.sub.2, CF.sub.3, F, Cl or Br. In most of these compounds, R.sup.6 and R.sup.7 are different, one of these radicals usually being an alkyl or alkoxy group. However, other variants of the envisaged substituents can also be used. Many such substances or mixtures thereof are commercially available. All these substances can be obtained by methods which are known from the literature. The phases according to the invention contain about 0.1 to 99%, preferably 10 to 95%, of one or more compounds of the formula I and/or II. Liquid crystal phases according to the invention containing 0.1-40%, preferably 0.5-30%, of one or more compounds of the formula I and/or II are furthermore preferred. The phases according to the invention are prepared in a manner which is customary per se. As a rule, the components are dissolved in one another, advantageously at elevated temperature. The liquid crystal phases according to the invention can be modified by suitable additives so that they can be used in all the types of liquid crystal display elements which have hitherto been disclosed. Such additives are known to the expert and are described in detail in the literature. For example, it is possible to add conductive salts, preferably ethyldimethyl-dodecyl-ammonium 4-hexyloxybenzoate, tetrabutylammonium tetraphenyl boranate or complex salts of crown ethers (compare, for example, I. Haller et al., Mol. Cryst.Liq.Cryst. Volume 24, pages 249-258 (1973)) to improve the conductivity, dichroic dyestuffs to prepare coloured guest/host systems or substances for modifying the dielectric anisotropy, the viscosity and/or the orientation of the nematic phases. Such substances are described, for example, in German Offenlegungsschriften 2,209,127, 2,240,864, 2,321,632, 2,338,281, 2,450,088, 2,637,430, 2,853,728 and 2,902,177. The chemical reactions described above are generally disclosed in terms of their broadest application to the preparation of the compounds of this invention. Occasionally, the reactions may not be applicable as described to each compound included within the disclosed scope. The compounds for which this occurs will be readily recognized by those skilled in the art. In all such cases, either the reactions can be successfully performed by conventional modifications known to those skilled in the art, e.g., by appropriate protection of interfering groups, by changing to alternative conventional reagents, by routine modification of reaction conditions, etc., or other reactions disclosed herein or otherwise conventional, will be applicable to the preparation of the corresponding compounds of this invention. In all preparative methods, all starting materials are known or readily preparable from known starting materials. Of course, the compounds of this invention can also be used to prepare one another using the reactions discussed above and other conventional methods. Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The following preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever. In the following examples, all temperatures are set forth uncorrected in degrees Celsius; unless otherwise indicated, all parts and percentages are by weight. In the examples, m.p. is the melting point and c.p. is the clear point of a liquid crystal substance. "Customary working up" means: water is added, the mixture is extracted with methylene chloride, the organic phase is separated off, dried and evaporated and the product is purified by crystallization and/or chromatography.

US Referenced Citations (4)

Number	Name	Date
4181625	Eidenschink et al.	Jan 1980
4510069	Eidenschink et al.	Apr 1985
4629581	Petrzilka et al.	Dec 1986
4659499	Ferrato	Apr 1957

Foreign Referenced Citations (1)

Number	Date	Country
3328638	Feb 1985	DEX

Continuations (1)

	Number	Date	Country
Parent	705811	Feb 1985

Continuation in Parts (1)

	Number	Date	Country
Parent	526927	Aug 1983

Cyclohexane derivatives

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