JPH01301654A - Production of phenyl chlorothioformates - Google Patents

Abstract

PURPOSE:To obtain the subject compound in improved distillation yield, by reacting a phenolic compound with thiophosgene in a specific solvent in the presence of a dehydrohalogenation reagent, separating the solution of produced crude product, washing with an alkaline aqueous solution and distilling the product. CONSTITUTION:A phenolic compound is made to react with thiophosgene in a mixture of water and an organic solvent (e.g., benzene or CCl4) in the presence of a dehydrohalogenation reagent (e.g., NaOH, KOH or Na2CO3). The obtained solution of crude phenyl chlorothioformate compound is separated, added with an alkaline aqueous solution, stirred, separated into liquid layers by leaving at rest, washed and then purified by distilling under normal pressure or reduced pressure to obtain the objective compound having high purity and useful as a synthetic intermediate for pharmaceuticals and agricultural chemicals on an industrial scale at a distillation yield of >=95% in high purity. The amount of the alkali is 1-3 equivalent based on the phenolic compound and the concentration of the alkaline aqueous solution is 5-30wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing phenyl lyrorothioformates. Phenyl chlorothioformates are important as synthetic intermediates for pharmaceuticals and agricultural chemicals.

<Prior art> A method is known in which phenyl lyrorothioformates are produced by reaction of phenols and thiophosgene in an organic solvent-water mixed solvent in the presence of a dehalogenation reagent, and then distilled. Japanese Patent Publication No. 60-61562
Publication No.).

<Problems with the prior art> The production method of the prior art is produced by distilling the crude phenyl-rorothioformates after the completion of the reaction, but the distillation yield is as low as 95% or less, and Decomposition products such as diphenyl thiocarbonates are produced.

In addition, it is relatively difficult to separate the phenols present as impurities from the phenyl-rolotioformates by distillation, and precision distillation is required.

As a result of intensive study on the production method of phenyl lyrorothioformates, the present inventors found that it is impurities or raw material phenols that cause a decrease in distillation yield.
It has also been found that it is difficult to remove the impurities by controlling the reaction conditions or by adding an alkali to the reaction solution after the reaction is completed and then branching.

Furthermore, after the completion of the reaction, by washing the organic solution of the branched crude phenylchlorothioformates again with an alkaline aqueous solution, the compound can be removed to the container, and then by distillation, the distillation yield can be increased. It was discovered that it can be produced with a high yield of 95% or more, and the present invention was completed.

That is, the present invention involves separating a solution of crude phenyl chlorothioformates produced by the reaction of phenols and thiophoscene in an organic solvent-water mixed solvent in the presence of a dehalogenation reagent, and then converting the solution into an aqueous alkali solution 11K. The present invention provides a method for producing phenyl chlorothioformates, which comprises washing with water and then distilling them.

The present invention will be explained in detail below.

The phenols of the phenyl lyrothioformates that can be applied to the present invention include unsubstituted phenol, alkyl-substituted phenols such as methylphenol, ethylphenol, and terL-butylphenol, β-naphthol,
5.6.7.8-Tetrahydro- can be present.

Any organic solvent can be used in the present invention, preferably halogenated hydrocarbons such as chloromethane, chloroform, carbon tetrachloride, and aromatic hydrocarbons such as benzene, toluene, quincylene, etc.

The amount of alkali used in the reaction is 1% per phenol.
It is fine to use an equivalent amount or more, but using more than 3 times the equivalent amount may result in a decrease in yield, although this may be beneficial. As for the concentration, it can be used at any concentration, and there is no problem as long as the amount of water is sufficient to dissolve the inorganic salt by-produced in the reaction, and usually an aqueous alkali solution of 5 to 30 wt% is used.

Examples of the alkali used in the reaction and the operation after liquid separation include thorium hydroxide, potassium hydroxide, lithium hydroxide, rubyrum hydroxide, senium hydroxide, beryllium hydroxide, magnesium hydroxide, and hydroxide. Hydroxides such as calcium, strontium hydroxide, and barium hydroxide can be fried, and as carbonates or hydrogen carbonates, the above-mentioned alkali metal or alkaline earth metal salts can be fried. Preferred are sodium hydroxide, sodium carbonate, sodium bicarbonate, and potassium hydroxide in terms of economy.

/)) The amount of alkaline aqueous solution used in the immersion operation is:
For the crude phenyl lyrorothioformate solution, branching operation or solution volume within a convenient range is sufficient, and the amount of alkali present is theoretically equivalent to the phenols contained as impurities. It is fine if it is more than that, but preferably,
It is 1.05 equivalent or more relative to phenols. Also,
The use of 10.0 equivalents or more will provide equivalent benefits.
This is not preferable since it may not result in the decomposition of phenyl chlorothioformate. It is possible to use any alkaline concentration, but 1~3Q w
t% and/or the solubility of the alkali, there is no problem.

Various methods can be used for washing, or it is sufficient to add an aqueous alkali solution to a solution of crude phenyl rolotioformate, stir, and then settle and branch.

The distillation method may be either normal pressure distillation or reduced pressure distillation, depending on the type of phenyl lyrorothiothioformate.

<Effects of the Invention> According to the present invention, it has been possible to purify phenyl lyrorothioformates and improve the distillation yield, and a production method on an industrial scale has been established.

<Examples> Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited only to these Examples.

Example 1 1ρ equipped with stirrer, thermometer and 300ml dropping funnel
430 g of phenol, 150 g of benzene, and 55.0 g of thiophosgene were weighed into a third round-bottomed flask, and the flask was cooled with water.

Next, 240 ml of a 12 wt % potassium hydroxide aqueous solution was put into the dropping funnel, and the potassium hydroxide aqueous solution was added dropwise over 1 hour while maintaining the temperature at 20 to 40°C without stirring the inside of the flask. After finishing dropping the potassium hydroxide aqueous solution,
The mixture was further stirred at room temperature for 3 hours.

After the reaction is complete, transfer the reaction solution to a 1fI separation row 1 and separate the pentcene phase.t5/L, crude phenyl chlorothiopormei! - Obtained 230g of solution. As a result of analysis by gas chromatography, crude phenyl chlorothiopormate containing ff177.3g - phenol content 0.86g
Met.

The obtained crude phenyl chlorothioformate solution was transferred again to the separating funnel, and the solution was
% potassium hydroxide aqueous solution was added, and the mixture was shaken for 1 minute and allowed to settle. After separation, the resulting liquid was analyzed by chromatography and found to contain 77.0 g of phenyl chlorothiopormate.

The phenol content was 0.01 g or less.

Furthermore, the solution was concentrated and then distilled under reduced pressure to obtain 76.0 g of purified phenyl chloride. As a result of gas chromatography analysis, the yield was 96.
43%, distillation yield 98.7%, purity 99.6%, and no phenol was present in the distillate.

Example 2 Into the same apparatus as in Example 1, 68.2 g of m-tert-butylphenol, 150 g of carbon tetrachloride, and 5 g of thiophoscene were added.
5.0 g was weighed out and the flask was cooled.

Next, 240 ml of 11 wt % thorium hydroxide aqueous solution was put into the dropping funnel and added dropwise over 1 hour under the same conditions as in Example 1, and further stirred at room temperature for 3 hours.

After the reaction was completed, the reaction solution was transferred to a 1 g branching row 1, the carbon tetrachloride phase was separated, and the crude m-tert-butylphenyl
255 g of a dirorothioformate solution was obtained. As a result of analysis by gas chromatography, the content of m-tert-butylphenyl rolotioformate was 100.8 g, m-
It contained 2.05 g of tert-butylphenol.

11J of the crude m-tert-butylphenylchlorothioformate solution was transferred to the separating funnel again, and 20 ml of 5 wt% sodium hydroxide aqueous solution was added to the solution.
was added, shaken for 2 minutes, and allowed to settle.

After branching, the resulting solution was analyzed by gas chromatography and found to contain 100.5 g of m-tert-butylphenyl rolotioformate.

The m-tert-butylphenol content was 0.01 g or less.

Furthermore, by condensing the solution and then distilling it,
98.9 g of purified m-tert-butylphenyl dirorothioformate was obtained. As a result of gas chromatography analysis, the yield was 95.2%, the distillation yield was 984%, and the purity was 99%.
．． 4%, and did not contain m-tert-butylphenol.

Comparative Example 1 Using the same apparatus as in Example], 42.9 g of phenol, 55.0 g of thiophosgene, and 150 g of benzene were added.

], l wt% thorium hydroxide aqueous solution 240ml
A similar reaction was carried out using 1. The resulting reaction solution was separated to obtain 232 g of a crude phenyl chlorothioformate solution. When analyzed by gas chromatography,
It contained 1-77.0 g of phenyl rolotioformei and 0.92 g of phenol.

By concentrating this reaction solution and distilling it under reduced pressure, 70.8 g of purified phenyl polyrorothioformate was obtained in a concentration of 1+y. As a result of gas chromatography analysis, the yield was 88.7%.
The distillation yield was 91.2%, the purity was 98.0%, and the phenol content was 1.5%.

Comparative Example 2 In the same apparatus as in Example 1, m-tert-butylphenol 67, Og, carbon tetrachloride 150g, thiophosgene 5
5.0g, 11wt% thorium hydroxide aqueous solution 1t)i
A similar reaction was carried out using 240 g.

After the reaction was completed, the water-carbon tetrachloride mixed reaction solution was transferred to a 1 g branch funnel, 100 g of a 10 wt% aqueous sodium hydroxide solution was added thereto, and the mixture was shaken for 1 minute and allowed to settle.

After branching, 253 g of crude m-tert-butylphenylchlorothioformate solution were obtained. Analysis by gas chromatography revealed that it contained 99.7 g of m-tert-butylphenyl dirorothioformate and 1.35 g of m-tert-butylphenol.

The obtained crude m-tert-butylphenyl chlorothioformate solution was concentrated and then distilled under reduced pressure to obtain 92.3 g of purified m-tert-butylphenyl chlorothioformate. As a result of analysis by gas chromatography, the yield of m-tert-butylphenyl rolotioformate was 88.5%, the distillation yield was 90.5%,
The purity was 97.8%, and the m-tert-butylphenol content was 1.1%.

Comparative Example 3 100 g of m-tert-butylphenyl lylorothioformate and 20 g of m-tert-butylphenol were placed in a 200 ml eggplant-shaped flask equipped with a cooling condenser, and the mixture was kept at 150°C for 8 hours while stirring. did. After cooling, gas chromatography analysis showed that m
-tert-butylphenyl lylorothioformate 7
It was 7.5 g x m-tert-phenol 4.5 g.

Claims (1)

[Claims] In an organic solvent-water mixed solvent, in the presence of a dehalogenation reagent,
1. A method for producing phenylchlorothioformates, which comprises separating a solution of crude phenylchlorothioformates produced by a reaction between phenols and thiophosgene, washing the solution with an aqueous alkaline solution, and then distilling it.