Base-catalyzed dehydration of substituted cis-1,2-dihydroxycyclohexa-3,5-dienes

Abstract

A process for dehydrating compounds of the formula ##STR1## where --R is --CH.dbd.CH.sub.2, --C.tbd.CH --C.tbd.N or ##STR2## in an aqueous solution thereof is disclosed. In the case where R is --CH.dbd.CH.sub.2 or --C.dbd.CH, the temperature is preferably at least 50.degree. C. and preferably 75.degree. to 100.degree. C. The base is at least 0.1N and preferably 1.0 to 8N. Preferred bases are NaOH, KOH and C.sub.5 OH. In the case where --R is C.tbd.N, the temperature preferably is 20.degree. to 50.degree. C.

Description

FIELD OF THE INVENTION

The present invention relates to the dehydration of various substituted cis-1,2-dihydroxycyclohexa-3,5-dienes to form the corresponding m-substituted phenols. The use of a base, optionally at elevated temperature optimizes production of the m-substituted phenols over the o-substituted phenols.

BACKGROUND OF THE INVENTION

Compounds of the general formula ##STR3## have been chemically dehydrated to phenols by acidification. In general, the 2-hydroxy isomer predominates, or is the exclusive product of the reaction. The present invention relates to the use of a base to optimize production of the 3-hydroxy isomer of certain such compounds.

U.S. Pat. No. 4,508,822 discloses the preparation of compounds of the general formula ##STR4## wherein X and Y may be the same or different, and represent hydrogen, halogen, ceryl, or cyano groups except that X and Y cannot both be hydrogen, using strains of Pseudomonas putida.

U.S. Pat. No. 4,532,209 discloses the production of p-cresol by the acidification of an aqueous solution of 4-methylcyclohexa-3,5-diene-1,2-diol-1-carboxylic acid.

Formation of (+)-cis-2,3-dihydroxy-1-methylcyclohexa-4,6-diene from Toluene by Pseudomonas putia, by D. T. Gibson et al., Biochemistry, pp. 1626-1630, Vol. 9, (1970) discloses the acid catalyzed dehydration of (+)-cis-2,3-dihydroxy-1-methylcyclohexa -4,6-diene.

U.K. Patent No. 2,203,150 B discloses preparing fluorophenols by dehydrating 1,2-dihydroxy-3-fluorocyclohexa-3,5-diene in the presence of base and subsequently recovering 2 and/or 3-fluorophenol. The use of base does not make the reaction overly selective for 3-fluorophenol.

Initial Reactions in the Oxidation of Ethylbenzene by Pseudomonas putida, by D. T. Gibson et al., Biochemistry, pp. 1520-1527, Vol. 12, No. 8, (1973) discloses the oxidation of ethyl benzene to (+)-cis-3-ethyl-3,5-cyclohexadiene-1,2-diol and (+)-cis-3-(1'-hydroxyethyl)-3,5-cyclohexadiene-1,2-diol by Pseudomonas putida as well as the oxidation of acetophenone to cis-3 (1'-oxoethyl)-3,5-cyclohexadiene -1,2-diol. The reference also discloses the acid catalyzed dehydration of (+)-cis-3-ethyl-3,5-cyclohexa-diene-1,2-diol.

Biodegradations Yield Novel Intermediates For Chemical Synthesis, D. W. Ribbons et al., Biotechnology and Biodegradations, pp. 213-245, London discloses the use of mutants of P. putida to form compounds of the formula ##STR5## where R.sup.1 =R.sup.2 =H; R.sup.1 =Cl, R.sup.2 =H; R.sup.1 =F, R.sup.2 =H; R.sup.1 =CH.sub.3, R.sup.2 -H; R.sup.1 =Ph, R.sup.2 =H; R.sup.1 =CF.sub.3, R.sup.2 =H; Rl=C2H5, R.sup.2 =H; R.sup.1 =HC=CH.sub.2, R.sup.2 =H; R.sup.1 =C.tbd.CH, R.sup.2 =H; R.sup.1 =CH.sub.3, R.sup.2 =F; R.sup.1 =CH .sub.3, R.sup.2 =Cl; R.sup.1 =CH.sub.3, R.sup.2 =Br.

SUMMARY OF THE INVENTION

The present invention relates to the base catalyzed dehydration of compounds of the formula ##STR6## here --R is --CH=CH.sub.2, --CH.tbd.CH, or --C.tbd.N, to form a compound of the formula

DETAILED DESCRIPTION

Generally a cell-free aqueous broth containing a cis-dihydrodiol at a concentration in the range of 200-5,000 parts per million (ppm) is used. To optimize dehydration to the meta isomer when --R is --CH=CH.sub.2, or --C.tbd.CH, the broth is quickly heated to at least 50.degree. C. and preferably to from 75.degree. to 100.degree. C. In the case where --R is --C.tbd.N the reaction is preferably performed at 20.degree. to 50.degree. C. Then a solution of alkali at the elevated temperature is quickly added and mixed. The final concentration of alkali is at least 0.1N, preferably 1.0N or higher such as up to 8N. The solution is held at the elevated temperature at least 15 minutes and preferably one hour or even longer such as up to 10 hours. The mixture is then cooled to 20 to 30.degree. C. and the phenols recovered such as by extraction. The preferred bases are sodium hydroxide, potassium hydroxide and cesium hydroxide with sodium hydroxide being preferred because of cost.

The compounds produced by the process are useful as intermediates for producing polymeric materials.

EXAMPLES

In the Examples an aqueous solution of 500 ppm of the starting material was treated with reagents reported in the Tables to bring the normality of the overall solution to the value reported. In the Tables RT stands for room temperature.

EXAMPLE 1

Treatment of 2,3-dihydroxy-1-ethynylcyclohexa-4,6-diene. ##STR8##

TABLE 1______________________________________ Wt. % Products of DehydrationTreatment of 2-Hydroxy 3-HydroxyPhenylacetylene Diol Phenylacetylene Phenylacetylene______________________________________0.3N NaOH/RT/1 hr. 58 420.6N NaOH/RT/1 hr. 53 470.9N NaOH/RT/1 hr. 51 490.9N NaOH/75.degree. C./1 hr. 11 89 1N HCl/RT/1 hr. 95 5 1N NaOH/75.degree. C./1 hr. 4 96 1N HCl/RT/1 hr. 93 7______________________________________

EXAMPLE 2

Treatment of 2,3-dihydroxy-1-vinylcyclohexa-4,6-diene. ##STR9##

TABLE 2______________________________________ Wt. % Products of DehydrationTreatment of 2-Hydroxy 3-HydroxyStyrene Diol Styrene Styrene______________________________________1N HCl/RT 80 201N NaOH/RT 77 231N NaOH/75.degree. C. 6 945N NaOH/75.degree. C. 0 100______________________________________

EXAMPLE 3

Treatment of 2,3-dihydroxy-1-cycanocyclohexa-4,6-diene. ##STR10##

TABLE 3______________________________________Treatment of PPM Products of DehydrationBenzonitrile Diol 2-Cyanophenol 3-Cyanophenol______________________________________1N HCl/RT/1 hr. 14 111N HCl/75.degree. C./1 hr. 90 431N NaOH/RT/1 hr. 0 1581N NaOH/75.degree. C./1 hr. 0 0______________________________________

EXAMPLE 4

Treatment of 2,3-dihydroxy-1-phenylcyclohexa-4,6-diene. ##STR11##

TABLE 4______________________________________Treatment of PPM Products of DehydrationBiphenyl Diol 2-Phenyphenol 3-Phenylphenol______________________________________1N HCl/RT/1 hr. 345 2541N NaOH/RT/1 hr. 293 1211N NaOH/75.degree. C./1 hr. 49 402______________________________________

Claims

1. A process comprising treating an aqueous solution of a starting compound of the formula

where --R is --CH=CH.sub.2, --C.tbd.CH [--C.tbd.H], --C.tbd.N or ##STR12## at a temperature of at least 20.degree. C. with an aqueous basic solution at about the same temperature to bring the normality of the resulting basic solution to at least about 1.0 and maintaining the temperature about the same for at least 15 minutes and recovering a product principally of the formula ##STR13##

2. The process of claim 1 wherein the base is sodium hydroxide, potassium hydroxide or cesium hydroxide.

3. The process of claim 1 wherein --R is --C.tbd.CH, --CH=CH.sub.2 or ##STR14##

4. The process of claim 3 wherein the temperature is from about 75.degree. to about 100.degree. C.

5. The process of claim 4 wherein the basic solution is held at 75.degree. to 100.degree. C. for from about 1 to about 10 hours.

6. The process of claim 5 wherein from 200 to 5,000 ppm of the starting compound is present.

7. The process of claim 6 wherein --R is --C.tbd.CH.

8. The process of claim 6 wherein --R is --CH=CH.sub.2.

9. The process of claim 6 wherein --R is ##STR15##

10. The process of claim 2 wherein --R is --C.tbd.N and the temperature is 20.degree. to 50.degree. C.