IE42800B1 - Conversion of esters - Google Patents

Abstract

1507429 Amides and thioamides ANIC SpA 15 April 1976 [23 April 1975] 15729/76 Heading C2C [Also in Division C3] Compounds X-A-NH-CO-X1-Y, where X is H or a group -NHCOSR, -NH 2 , -ZNH 2 or -ZNHCOSR (Z being derived by removing a hydrogen atom from an alkyl, aryl, cycloalkyl, aralkyl or alkaryl radical and R being hydrocarbyl); Y is an organic radical; X1 is O, S or NH; and A is arylene optionally substituted by one or more of halogen, hydrocarbyl and alkoxy or optionally substituted alkylene are made by reacting an ester X-A-NH-COSR with a compound Y-X1-H and, if desired, removing a by-product H-S-R.

Description

This invention relates to a process for the conversion of esters of thiocarbamic acids.

The present invention provides a process for the conversion of an ester of thiocarbamic acid having the formula X - A - NH - C - S - R, II wherein R is a hydrocarbon radical; either A is an arylene radical which is unsubstituted or substituted by at least one substituent selected from halogen atoms, hydrocarbon radicals and alkoxy groups, or A is an alkylene radical having from 1 to 15 carbon atoms, which is straight-chain or branched and which is unsubstituted or substituted; and X is a hydrogen atom or a group having the formula - NH - C - S - R, - NH„ II 2 o H, - N - Z - or R-S-C-NH-Z-, 2 II o where R is as defined above and the divalent radical Z is derivable by removal of a hydrogen atom from the alkyl, aryl, cycloalkyl, alkaryl or aralkyl radical which is unsubstituted or substituted; to a compound of the formula - 2 42800 X - A - NH - C - X1 - Υ II 0 wherein X and A are as defined above, X' is 0, S or NH, and Y is an organic radical; which process comprises reacting the ester with a compound of the formula X-X' - H where X1 and Y are as defined above.

The ester starting materials are known, and they may be obtained, in the main, either by reacting an isocyanate with a mercaptan, and by reacting an amine with a chlorothiocarbonate; they can also be produced according to the reaction which forms the subject-matter of one of our Patent Specifications, viz. 867/76.

By means of the present invention it is possible to subject these esters to appropriate reactions so as to obtain valuable products, which have important industrial applications.

The reaction of the present invention is preferably carried out in an organic solvent at a temperature preferably in the range from 50°C to the boiling point temperature of the solvent.

It is also possible to employ an inert gas stream, preferably a nitrogen stream, to remove from the reaction environment the evolved mercaptan without causing any entrainment of the desired product in the gas stream; thus the mercaptan of formula H - S - R can be removed from the reaction zone to promote completion of the reaction. The reaction can be carried out in the presence of a catalytic system which can be composed by a tertiary amine, more parti cularly di azabi cyclooctane.

In the following Examples, which illustrate the present invention, when an unspecified inert gas is referred to, that gas was nitrogen.

EXAMPLE 1.

Into a flask equipped with a condenser were introduced 1.68 grams of S-methylthiocarbanilate (10 millimoles), 0.88 gram of normal butylamine (12 millimoles) and 10 ml of benzene. The mixture was heated to obtain a vigorous refluxing of the solvent, whilst concurrently passing a stream of an inert gas through the flask. The gas which evolved was passed through a trap which was cooled to -78°C. After one hour, 9.5 millimoles of methyl mercaptan were recovered from the trap. From the reaction solution, by evaporation of the solvent, there were isolated 1.90 grams of N-normal butyl-Ν'-phenyl urea.

Yield 99«.

EXAMPLE 2.

Into a flask equipped with a condenser were introduced 1.68 grams of S-methylthiocarbanilate (.10 millimoles), 1.12 grams of aniline (12 millimoles) and 10 ml of xylene. The mixture was heated sufficiently to maintain a vigorous reflux of the solvent, whilst concurrently passing a stream of an inert gas through the flask. The gas which evolved was passed through a trap cooled to -78°C. After one hour there were recovered from the trap 9.4 millimoles of methyl mercaptan; from the reaction solution there were isolated by filtration 2.0 grams of N,Nl-diphenylurea. Yield 95%.

EXAMPLE 3.

Into a flask equipped with a condenser were introduced 1.68 grams of S-methylthiocarbanilate (10 millimoles), 0.89 gram of normal butanol (12 millimoles), 0.10 gram of diazabicyclooctane and 10 ml of toluene. The mixture was heated sufficiently to obtain a vigorous reflux of the solvent, whilst concurrently passing a stream of inert gas through the reactor. The gas which evolved was passed through a trap which was cooled to -78°C. After two hours there were recovered in the trap 9.8 millimoles of methyl mercaptan. From the reaction solution, by evaporation of the solvent and reerystallization of the residue from a mixture of benzene and petroleum-ether, there were isolated 1.85 grams of normal butyl carbanilate. Yield 86«.

EXAMPLE 4.

Into a flask equipped with a condenser were introduced 1.68 grams of S-methylthiocarbanilate (10 millimoles), 1.13 grams of phenol (12 millimoles), 438C Ο 0.10 gram of diazabicyclooctane and 10 ml of xylene. The mixture was heated sufficiently to obtain a vigorous reflux of the solvent, whilst concurrently passing a stream of inert gas through the flask. The gas which evolved was passed through a trap which was cooled to -78°C. After two hours there were recovered in the trap 9.9 millimoles of methyl mercaptan. By adding petroleum ether to the reaction solution, 2.03 grams of phenylcarbanilate were crystallized out. Yield 95«.

EXAMPLE 5.

Following exactly the same procedure as described in Example 4, but reacting 1.68 grams of S-methylthiocarbanilate with 1.3 grams of thiophenol in the presence of 0.10 gram of diazabicyclooctane, in 10 ml toluene, 1.85 grams of S-phenylthiocarbanilate were obtained. Yield 80«.

EXAMPLE 6.

Into a flask equipped with a condenser were introduced 1.35 grams of toluene-2:4-dithiocarbamic acid S,S'-dimethylester (5 millimoles), 1.4 grams of normal heptanol (12 millimoles), 0.10 gram of diazabicyclooctane and 20 ml of xylene. The mixture was heated whilst concurrently passing a stream of an inert gas through the flask. The gas which evolved was passed through a trap which was cooled to -78°C. After one hour 9.4 millimoles of methylmercaptan were recovered in the trap. The slightly cloudy reaction solution was filtered and evaporated to one quarter of its initial volume. Upon the addition of petroleum ether and cooling to 0°C, 1.4 grams of toluene-2:4-dicarbamic acid diheptylester crystallized out. Yield 70«.

EXAMPLE 7.

Into a flask equipped with a condenser were introduced 1.35 grams of toluene-2:4-dithiocarbamic acid - S,S'-dimethylester (5 millimoles), 0.94 gram of phenol (10 millimoles), 0.10 gram of diazabicyclooctane and 20 ml of xylene The mixture was heated sufficiently to maintain a vigorous refluxing of the solvent, whilst concurrently passing a stream of nitrogen through the reactor. 43800 The gas which evolved was forwarded to a trap which was cooled to -78°C.

After 1.5 hours there were recovered in the trap 9.5 millimoles of methyl mercaptan. By cooling the reaction solution there were isolated 1.8 grams of toluene-2:4-dicarbamic acid-diphenyl ester. Yield 99%.

All of the compounds obtained in the preceding Examples were identified by comparison with samples obtained from conventional syntheses.

EXAMPLE 8, Into a flask equipped with a condenser were introduced 1.35 grams of toluene-2:4-dithiocarbamic acid - S,S‘-dimethyl ester (5 millimoles), 0.38 gram of propylene-1:2 glycol (5 millimoles), 0.08 gram of diazabicyclooctane and 20 ml of xylene. The mixture was heated sufficiently to obtain a vigorous reflux of the solvent, whilst concurrently passing a stream of inert gas through the flask. The gas which evolved was passed through a trap cooled to -78°C. After one hour, there were recovered in the trap 9.3 millimoles of methyl mercaptan. Once the solvent had been removed by filtration, there were recovered 1.5 grams of solid product. The I.R. spectrum in KBr exhibited the following characteristic absorptions of urethane (3 microns; 5.8 microns). The polymer showed, on different thermal analysis, a vitreous transition (Tg) at 60°C.

Claims (9)

1. A process for the conversion of an ester of thiocarbamic acid having the formula x-a-nh-c-s-r, II wherein R is a hydrocarbon radical; either A is an arylene radical which is unsubstituted or substituted by at least one substituent selected from halogen atoms, hydrocarbon radicals and alkoxy groups, or A is an alkylene radical having from 1 to 15 carbon atoms, which is straight-chain or branched and which is unsubstituted or substituted; and X is a hydrogen atom or a group having the formula - 6 42800 - NH - C - S - R, -NH,, II 2 H, - N - Z - or R - S - C - NH - Z -, 2 II wherein R is as defined above and the divalent radical Z is derivable by removal of a hydrogen atom from an alkyl, aryl, cycloalkyl, alkaryl or aralkyl radical which is unsubstituted or substituted; to a compound of the formula X-A-NH-C-X’ - Y II wherein X and A are as defined above, X 1 is 0, S or NH, and Y is an organic radical; which process comprises reacting the ester with a compound of the formula Y - X' .- H where X 1 and Y are as defined above.

2. A process according to Claim 1 wherein the reaction takes place in the presence of a catalyst comprising a tertiary amine.

3. A process according to Claim 2, wherein the tertiary amine is diazabicyclooctane.

4. A process according to Claim 1, 2 or 3, wherein the reaction is carried out in an organic solvent.

5. A process according to Claim 4, wherein the reaction temperature is maintained in the range from 50°C to the boiling point of the solvent.

6. A process according to any preceding claim, wherein the reaction is carried out in the presence of a nitrogen stream.

7. A process according to any preceding claim, which includes the removal from the reaction zone of a by-product having the formula H - S - R where R is as defined above.

8. A process according to Claim 1, substantially as described in any one of the foregoing Examples.

9. A compound of the formula