Process for preparing dialkyl and diaryl phosphonothioic halides

BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The present invention relates to a new and improved process for the preparation of dialkyl and diaryl phosphonothioic halides.
2. THE PRIOR ART
Dialkylphosphonothioic halides have been prepared in the past by reacting thionophosphinic acids with PCl.sub.5 according to the following reaction scheme:
R.sub.2 P(S)OH + PC1.sub.5 .fwdarw. R.sub.2 P(S)Cl + POCL.sub.3 + HCl. (1)
This reaction is described in Organic Phosphorus Compounds, G. M. Kosolapoff and L. Maier, Vol. 4, p. 158 (Wiley --Interscience, 1972).
A method of preparing dialkarylthiophosphinic chlorides is described in Chemical Abstracts, Vol. 69, p. 10021 at 106875d(1968). According to this method, a mixture of white phosphorus, alkaryl halide and CS.sub.2 or PSCl.sub.3 is heated at 270.degree. to 300.degree. C. in the presence of a catalytic amount of iodine or coiodines. The dialkarylthiophosphinic chloride product is then separated from the mixture.
Dialkyl and diaryl phosphinothioic halides are useful as pesticides and as intermediates in preparation of pesticides and other organophosphorus compounds. The compounds also act as collectors and therefore can be used to increase the effectiveness of flotation of copper ores.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a new method for preparing compounds of the formula: ##STR1## wherein R is a C.sub.1 -C.sub.20 alkyl radical and the aryl (1 and 2 fused rings) substituted derivatives thereof, cycloalkyl of 5-6 carbons in the ring and aryl radicals of up to 3 fused rings or biphenyl, and the C.sub.1 -C.sub.4 alkyl substituted derivatives of the cycloalkyl, aryl, or biphenyl groups and X is chlorine or bromine.
Typical alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl and eicosyl. Some suitable aralkyl groups are phenylmethyl, phenylethyl, phenylbutyl, phenyloctyl, phenylhexadecyl, and the corresponding naphthyl derivatives. Ring systems wherein R is cycloalkyl having 5-6 carbons in the ring are illustrated by cyclopentyl and cyclohexyl and its derivatives.
When R is an aryl of up to and including 3 fused rings, the benzene, naphthylene and anthracene series of ring compounds are included. Examples of suitable aryls and substituted aryls are phenyl, methylphenyl, ethylphenyl, propylphenyl, butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, propylnaphthyl, butylnaphthyl, anthryl, methylanthryl, propylanthryl, butylanthryl, dimethylphenyl, dimethylnaphthyl, diethylanthryl, and the like. Any of these radicals can contain one or more alkyl radicals and any isomeric form of said radicals can be used.
Biphenyl R groups include the C.sub.1 -C.sub.4 alkyl substituted derivatives such as methylbiphenyl and ditolyl. There can be one or more substituents as desired and said substituents can be in any isomeric position desired. The R group can be attached to the phosphorus at a position o, m, or p to the biphenyl linkage.
With respect to X, chlorine is preferred over bromine as it is inexpensive and reacts readily. Bromine, however, can be used if it is desired to have bromine in the final compound.
The method of the present invention consists of contacting an alkyl or aryl halide reactant of the formula:
RX II
wherein R and X are as defined above, with the phosphorus sesquisulfide reactant of the formula:
P.sub.4 S.sub.3. III
representative compounds within the Formula II are methyl chloride, propyl chloride, butyl chloride, octyl chloride, decyl chloride, dodecyl chloride, hexadecyl chloride, octadecyl chloride, eicosyl chloride and the corresponding bromo- substituted derivatives; chlorocyclopentane, chlorocylohexane and the corresponding bromosubstituted derivatives; chlorobenzene, bromobenzene, chlorotoluene (chloro)ethylbenzene, (bromo)ethylbenzene, (chloro)propylbenzene, (bromo)propylbenzene, (chloro) butylbenzene, (bromo)butylbenzene, chloronaphthylene, bromonaphthylene, (chloro)methylnaphthylene, (bromo)methylnaphthylene, (chloro)naphthylene, (bromo)ethylnaphthylene, (chloro)propylnaphthylene, (bromo)butylnaphthylene, chloroanthracene, (chloro) methylanthracene, bromoanthracene, (chloro)butylanthracene, chlcrodimethylbenzene, bromodimethylnaphthylene, chlorodiethylanthracene, and the like. In the aliphatic series above the C.sub.2 alkyl and in the aromatic series, isomeric forms of the same halide compound are formed. These are intended to be included in the definition of said halide compound. The foregoing compounds are given as illustrative and in no way are considered to be inclusive of all of the alkyl and aryl halides which can be used in the method of the present invention.
The phosphorus sesquisulfide is known and can be obtained commercially.
Stoichiometrically, the process of the present invention appears to require a ratio of six moles of alkyl or aryl halide per mole of phosphorus sesquisulfide. Reactants utilized in the process of the present invention generally are employed in stoichiometric amounts, although a slight excess of either reactant can be used if desired.
A theoretical reaction scheme according to the present invention can be postulated as follows:
6RX + P.sub.4 S.sub.3 .fwdarw. 3R.sub.2 P(S)X + PX.sub.3 ( 2)
wherein R and X are as defined above. As this reaction scheme is postulated only, applicants do not intend to limit their process thereto. The amounts given in the theoretical scheme, however, or those closely approaching said amounts should be used for efficiency and to avoid by-product formation and the need for extensive product purification and excess reactant recovery. Other products can result from incomplete reaction, decomposition or possible equilibrium of the following type:
R.sub.2 P(S)X + PX.sub.3 .revreaction. RP(S)X.sub.2 + RPX.sub.2 (III)
the process of the present invention is carried out at elevated temperature and at least an autogenous pressure. Temperatures of between about 200.degree. and about 400.degree. C. can be used although temperatures between about 250.degree. and about 330.degree. C. are preferred for the reaction to proceed to completion in a reasonable time. Pressures are determined by reaction temperature, the reactants, amounts of reactants used and the volume of the reaction vessel. The pressures range between about 500 to 5,000 pounds per square inch. Reaction times vary over relatively wide ranges depending upon reaction temperature and the reactivity of the alkyl or aryl halide. Generally, higher reaction temperatures require a shorter reaction time and the least reactive alkyl halides require longer reaction times. For example, methyl chloride requires a longer reaction time than the longer chain alkyl halides. Times of reaction can easily be determined by one skilled in the art. Typical reaction times are between about 1 and about 20 hours.
The process of the present invention can conveniently be effected by introducing the individual reactants into a reaction zone capable of withstanding elevated pressure, such as a metal bomb, autoclave, tube or other pressure vessel, and carrying out the reaction under at least the autogenous pressure developed by the reactants at the reaction temperature. An agitation means should be provided for said reaction zone. As the reaction is quite corrosive, especially for low molecular weight alkyl chlorides, a glass-lined reaction zone or an otherwise inert reaction zone is preferred. When aryl halides are utilized, the problem of corrosion is minimized and a metal-lined reaction zone, such as 316 stainless steel, can be used.
The products of the reaction are purified by conventional methods such as distillation, filtration, sublimation and extraction.
The identification of products is achieved by conventional methods such as elemental analysis, gas chromatography, refractive index, and nuclear magnetic resonance.
Illustrative of the compounds which can be prepared by the methods of the present invention are:
Alkyl:
(CH.sub.3).sub.2 P(S)Cl
(CH.sub.3).sub.2 P(S)Br
(C.sub.2 H.sub.5).sub.2 P(S)Cl
(CH.sub.2 H.sub.5).sub.2 P(S)Br
(C.sub.3 H.sub.7).sub.2 P(S)Cl
(C.sub.4 H.sub.9).sub.2 P(S)Cl
(C.sub.4 H.sub.9).sub.2 P(S)Br
(C.sub.5 H.sub.11).sub.2 P(S)Cl
(C.sub.8 H.sub.17).sub.2 P(S)Cl
(C.sub.8 H.sub.17).sub.2 P(S)Br
CYCLIC COMPOUNDS ##STR2##

The present invention will be more fully illustrated in the examples which follow:
EXAMPLE I
In a 40 ml. glass Carius tube were placed 3.5 grams P.sub.4 S.sub.3 (0.0159 mole). Then 4.2 grams CH.sub.3 Cl (0.083 mole) were condensed into the Carius tube by cooling to -70.degree. C. The tube was then sealed and placed in a cold 300 ml. autoclave. Methanol, 40 ml., was placed in the autoclave to counteract pressure in the Carius tube on heat-up. After closing the autoclave, it was placed under 300 psig nitrogen pressure to counteract the pressure inside the sealed tube during initial heating. The autoclave was heated at 200.degree.-210.degree. C. for 12 hours. After cooling, the Carius tube was removed and opened. Almost no reaction had taken place because most of the CH.sub.3 Cl was unreacted.
EXAMPLE II
Example I was repeated using 4.4 grams P.sub.4 S.sub.3 (0.02 mole) and 6.0 grams CH.sub.3 Cl (0.118 mole), however, the reaction temperature was 235.degree.-240.degree. C. for 12 hours. After cooling and opening the Carius tube, 2 grams of low boiling material evaporated (CH.sub.3 Cl). The remaining mixture of liquid and solid product was filtered to remove the solid material. The yield of liquid product was 2.6 grams. Analysis of the liquid product by .sup.31 P-nmr gave the following results:
______________________________________Chemical Shiftfrom H.sub.3 PO.sub.4ppm Compound Mole %______________________________________-219 PCl.sub.3 1.1-191.8 CH.sub.3 PCl.sub.2 2.6-177.3 Unknown 5.3-94.2 Unknown 12.8-86.3 (CH.sub.3).sub.2 PSCl 39.5-79.9 CH.sub.3 PSCl.sub.2 31.9-43.8 Unknown 2.6-40.2 Unknown 0.5-23.7 Unknown 3.6______________________________________
EXAMPLE III
Example II was repeated at a reaction temperature of 280.degree. C. for 12 hours. The crude product obtained was filtered to give 9.2 grams of yellow liquid and 0.2 grams solid material. Analysis of the liquid product by .sup.31 P-nmr gave the following results:
______________________________________Chemical Shiftfrom H.sub.3 PO.sub.4ppm Compound Mole %______________________________________-218.3 PCl.sub.3 13.9-194.8 CH.sub.3 PCl.sub.2 7.2-92.2 Unknown 2.7-87.4 (CH.sub.3).sub.2 P(S)Cl 59.9-81.3 CH.sub.3 P(S)Cl.sub.2 12.2-67.2 Unknown 0.9-44.3 Unknown 0.7-39.5 Unknown 0.3-23.6 Unknown 2.0______________________________________
EXAMPLE IV
Example II again was repeated at 325.degree. C. for 8 hours. The product was a dark liquid mixture. It was filtered to remove solids present. The yield of liquid product was 9.7 grams. Analysis by .sup.31 P-nmr gave the following results:
______________________________________Chemical Shiftfrom H.sub.3 PO.sub.4ppm Compound Mole %______________________________________-218.5 PCl.sub.3 15.0-194.2 CH.sub.3 PCl.sub.2 8.3-86.3 (CH.sub.3).sub.2 P(S)Cl 63.0-80.6 CH.sub.3 P(S)Cl.sub.2 13.7______________________________________
Analysis by H-nmr confirmed the major components containing methyl groups to be (CH.sub.3).sub.2 P(S)Cl and CH.sub.3 P(S)Cl.sub.2.
EXAMPLE V
In a 300 ml. 316 stainless steel autoclave, were placed 36.6 grams P.sub.4 S.sub.3 (0.166 mole) and 50.5 grams CH.sub.3 Cl (1.0 mole). The autoclave was heated at 250.degree. C. for 12 hours. The crude product was a black paste. 100 ml. chloroform was added followed by filtration. The yield of solid material was 42 grams (about 50% starting weight). The chloroform soluble material was distilled to give 22 grams of product which by H-nmr analysis was 70% (CH.sub.3).sub.2 P(S)Cl.
EXAMPLE VI
In a 40 ml. glass Carius tube were placed 2.0 grams P.sub.4 S.sub.3. (0.0091 mole) and 5.7 grams CH.sub.3 Br (0.059 mole). The sealed Carius tube was placed in a 300 ml. autoclave along with 40 ml. CH.sub.3 OH to equalize the pressure outside the sealed tube during heating. The autoclave was heated at 280.degree. C. for 8 hours. After cooling the Carius tube to -70.degree. C., it was opened and allowed to warm to room temperature. The weight loss of vent gas was 0.5 gram. The dark liquid in the tube was filtered to remove solids present (0.8 gram). The weight of liquid product was 6.4 grams.
Analysis by H-nmr indicated the presence of 59% (CH.sub.3).sub.2 P(S)Br and 41% CH.sub.3 P(S)Br.sub.2.
EXAMPLE VII
In a 40 ml. glass Carius tube were placed 2.0 grams P.sub.4 S.sub.3 (0.0091 mole) and 8.1 grams n-C.sub.8 H.sub.17 Cl (0.055 mole). The tube was sealed and placed in an autoclave containing 40 ml. methanol. The autoclave was heated at 250.degree. C. for 8 hours. After cooling, the Carius tube was found to contain a considerable amount of P.sub.4 S.sub.3. The tube was placed back in the autoclave and heated at 280.degree. C. for another 8 hours. After cooling, the Carius tube was opened and a light yellow liquid was removed. The yield was 8.1 grams.
Analysis by .sup.31 P-nmr gave the following results:
______________________________________Chemical Shiftfrom H.sub.3 PO.sub.4ppm Compound Mole %______________________________________-220 PCl.sub.3 5.7-195 C.sub.8 H.sub.17 PCl.sub.2 6.1-125 Unknown 2.3-116 (C.sub.8 H.sub.17 S).sub.3 P 3.4-114 Unknown 23.7-104 Unknown 4.2-102.5 (C.sub.8 H.sub.17).sub.2 P(S)Cl 30.9-89.5 C.sub.8 H.sub.17 P(S)Cl.sub.2 16.4-49.3 (C.sub.8 H.sub.17).sub.3 P(S) 5.7-45.2 Unknown 1.5______________________________________
EXAMPLE VIII
In each of two 3 ml. glass Carius tubes were placed 0.44 grams P.sub.4 S.sub.3 (0.002 mole) and 1.1 gram n-C.sub.4 H.sub.9 Cl (0.012 mole). The tubes were sealed and placed in autoclaves containing 40 ml. methanol. Tube No. 1 was heated at 250.degree. C. for 8 hours. Tube No. 2 was heated at 280.degree. C. for 8 hours. After cooling, the tubes were opened and the liquid analyzed by .sup.31 P-nmr which gave the following results:
______________________________________Heat at 250.degree. C. for 8 hours:(Part A)Chemical Shiftfrom H.sub.3 PO.sub.4ppm Compound Mole %______________________________________-211.3 C.sub.4 H.sub.9 SPCl.sub.2 21.0-201 Unknown 4.5-192.7 Unknown 1.1-188 (C.sub.4 H.sub.9 S).sub.2 PCl 20.1-118.9 Unknown 5.9-114.6 Unknown 3.7-104 (C.sub.4 H.sub.9).sub.2 P(S)Cl 18.7 type isomers-103 Unknown 4.2-63.7 Unknown 1.7-61.9 Unknown 3.1-53.1 Unknown 2.0-27.6 Unknown 0.8-27.3 Unknown 0.5+54.4 and 56.5 Unknown 12.5Heat at 280.degree. C. for 8 hours:(Part B)Chemical Shiftfrom H.sub.3 PO.sub.4ppm Compound Mole %______________________________________-220 PCl.sub.3 3.7-201 C.sub.4 H.sub.9 PCl.sub.2 1.5 type isomers-196 C.sub.4 H.sub.9 PCl.sub.2 4.6-177 Unknown 2.8-126 (C.sub.4 H.sub.9).sub.2 PCl 1.5-115 (C.sub.4 H.sub.9).sub.3 P 12.1-112.7 Unknown 7.7-105.5 (C.sub. 4 H.sub.9).sub.2 P(S)Cl 12.7 type isomers-104.6 (C.sub.4 H.sub.9).sub.2 P(S)Cl 3.3 type isomers-103.7 (C.sub.4 H.sub.9).sub.2 P(S)Cl 20.7-91.4 C.sub.4 H.sub.9 P(S)Cl.sub.2 20.9-90.4 Unknown 3.3-60.1 Unknown 1.5-50.7 Unknown 2.4-47.2 Unknown 1.1 99.8______________________________________
EXAMPLE IX
In a 3 ml. glass Carius tube were placed 0.437 grams P.sub.4 S.sub.3 and 1.3 grams n-C.sub.4 H.sub.9 Br. The sealed tube was placed in an autoclave containing 40 ml. methanol and heated at 250.degree. C. for 8 hours. After cooling the dark liquid was removed from the tube. Analysis by .sup.31 P-nmr gave the following results:
______________________________________Chemical Shiftfrom H.sub.3 PO.sub.4ppm Compound Mole %______________________________________-229.4 PBr.sub.3 22.4-192.1 Unknown 1.7-107.3 Unknown 6.2-92.0 (C.sub.4 H.sub.9).sub.2 P(S)Br 35.2-65.0 Unknown 3.4-40.8 C.sub.4 H.sub.9 PSBr.sub.2 29.3-21.1 Unknown 1.7______________________________________
EXAMPLE X
In a 40 ml. glass Carius tube were placed 2.2 grams P.sub.4 S.sub.3 and 6.7 grams chlorobenzene (C.sub.6 H.sub.5 Cl). After sealing, the tube was placed in an autoclave containing 40 ml. methanol and heated at 315.degree. C. for 12 hours. The tube was cooled and opened and the product filtered to remove traces of brown solids. The yield of light yellow colored liquid was 8.5 grams or 95.5%. The product was analyzed by .sup.31 P-nmr which gave the following results:
______________________________________Chemical Shiftfrom H.sub.3 PO.sub.4ppm Compound Mole %______________________________________-218.2 PCl.sub.3 10.4-161.5 C.sub.6 H.sub.5 PCl.sub.2 6.4-89.7 Unknown 0.5-80.9 (C.sub.6 H.sub.5).sub.2 PCl 1.5-79.5 (C.sub.6 H.sub.5).sub.2 P(S)Cl 61.4-75.4 Unknown 1.0-74.4 C.sub.6 H.sub.5 P(S)Cl.sub.2 12.9Other peaks Unknown 5.9______________________________________
EXAMPLE XI
In a 3 ml. glass Carius tube were placed 0.35 grams P.sub.4 S.sub.3 and 1.5 grams bromobenzene (C.sub.6 H.sub.5 Br). The sealed tube was heated in an autoclave containing 40 ml. methanol at 300.degree. C. for 12 hours. The dark liquid product was analyzed by .sup.31 P-nmr which gave the following results:
______________________________________Chemical Shiftfrom H.sub.3 PO.sub.4ppm Compound Mole %______________________________________-229 PBr.sub.3 40.8-151.9 C.sub.6 H.sub.5 PBr.sub.2 2.3-65.9 (C.sub.6 H.sub.5).sub.2 P(S)Br 35.8-19.8 C.sub.6 H.sub.5 P(S)Br.sub.2 18.9-10.2 Unknown 2.1-2.1 Unknown 0.2______________________________________
EXAMPLE XII
In a 300 ml. Hastelloy C autoclave were placed 22 grams P.sub.4 S.sub.3 (0.1 mole) and 67 grams of chlorobenzene (C.sub.6 H.sub.5 Cl) (0.6 mole). The autoclave was vented. The vent gas contained 1.1 grams HCl. The pour-out yield was 85.5 grams. The crude product was distilled and a low boiling fraction was obtained (916 grams) which assayed 42% chlorobenzene, 29% benzene and 28% PCl.sub.3 by glc analysis. The second fraction had a boiling point at 70.degree.-140.degree. C. at 0.05 mm Hg and weighed 21.3 grams. It consisted of a mixture of C.sub.6 H.sub.5 PCl.sub.2 and C.sub.6 H.sub.5 P(S)Cl.sub.2. The third fraction had a boiling point at 143.degree.-150.degree. C. and 0.05 mm Hg. and weighed 43.4 grams. n.sub.D.sup.20 =1.655 (literature n.sub.D.sup.20 for (C.sub.6 H.sub.5).sub.2 P(S)Cl = 1.6618, 1.6628, and 1.6563). The distillation residue was 6.3 grams.
The crude product was analyzed by .sup.31 P-nmr and gave the following results:
______________________________________Chemical Shiftfrom H.sub.3 PO.sub.4ppm Compound Mole %______________________________________-218.4 PCl.sub.3 7.3-161.8 C.sub.6 H.sub.5 PCl.sub.2 3.9-79.7 (C.sub.6 H.sub.5).sub.2 P(S)Cl 56.3-76.2 Unknown 1.0-74.6 C.sub.6 H.sub.5 P(S)Cl.sub.2 19.0-46.5 Unknown 4.8-35.0 Unknown 7.8______________________________________
The present invention is defined in the following claims.

Number	Name	Date	Kind
2449933	Giammaria	Sep 1948
2993929	Rattenbury	Jul 1961

Process for preparing dialkyl and diaryl phosphonothioic halides

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