JP2625850B2 - Method for producing thiophosgene - Google Patents

Description

The present invention relates to a method for producing thiophosgene. The thiophosgene obtained in the present invention is important as a raw material for synthesizing medicines and agricultural chemicals.

<Prior Art> As a method for producing thiophosgene by reducing perchloromethyl mercaptan with sulfur dioxide or hydrogen sulfide in an organic solvent-water mixed solvent in the presence of iodide, JP-A-62-176910 is known. is there.

JP-A-62-113712 discloses a method for producing thiophosgene by reducing perchloromethyl mercaptan with sulfur dioxide or hydrogen sulfide in an organic solvent-water mixed solvent in the presence of iodide and sulfur chloride. It is.

Furthermore, as a method for producing thiophosgene by reducing perchloromethyl mercaptan with sulfur dioxide in an organic solvent-water mixed solvent in the presence of potassium iodide, Czech Patent No. 103963 is known.

<Problems of the prior art> In the production of thiophosgene by a conventional liquid phase method, it is obtained as a solution in which thiophosgene is dissolved in an organic solvent,
Contains impurities such as iodide and sulfur chloride. For this reason, if only the separation operation of the aqueous layer after the reaction is completed, the above impurities are mixed in the thiophosgene solution, and if used in the next reaction without purification, the reaction yield and product purity may be adversely affected.

Although it is possible to purify by distillation, separation from an organic solvent is relatively difficult, and a precision distillation apparatus is required.

<Means to be Solved by the Invention> The present inventors have conducted intensive studies on a method for producing thiophosgene produced by the above-mentioned reaction, and found that impurities in an organic solution containing thiophosgene obtained by the reaction were dissolved in water, or However, it was found that thiophosgene was relatively stable in water and hardly soluble in water, and the present invention was completed.

That is, the present invention provides a method for separating thiophosgene produced by reducing perchloromethyl mercaptan with sulfur dioxide and / or hydrogen sulfide in an organic solvent-water mixed solvent in the presence of iodide and / or sulfur chloride, and then separating the thiophosgene. An object of the present invention is to provide a method for producing thiophosgene, wherein the method is washed with water one time or more in weight.

 Hereinafter, the present invention will be described in detail.

Perchloromethyl mercaptan, iodide and / or sulfur chloride are added to a mixed solvent of organic solvent and water, and sulfur dioxide and / or hydrogen sulfide are blown into the mixed solution to produce thiophosgene, and then the washing with water is performed. Do.

As the organic solvent used in the reaction, any solvent can be used, but preferably, a halogenated carbon such as chloroform, dichloromethane, carbon tetrachloride or the like, which does not react with thiophosgene and is relatively stable under reducing conditions, is used. Examples thereof include aromatic hydrocarbons such as hydrogen, benzene, toluene, and xylene.

The amount of water used in the reaction together with the organic solvent is desirably about twice or more mol per mol of perchloromethyl mercaptan.

Examples of the iodide include sodium iodide, potassium iodide, iodine, hydroiodic acid, and the like, and 0.3 to 1% by weight based on perchloromethyl mercaptan is used.

Examples of sulfur chloride include sulfur monochloride and sulfur dichloride.
Addition of 5 wt% is preferred.

These iodides and sulfur chlorides may be used alone or in combination.

As the amount of sulfur dioxide and / or hydrogen sulfide used,
About equimolar to 5 perchloromethyl mercaptan
The use of twice the molar amount is sufficient. The composition ratio of sulfur dioxide to hydrogen sulfide can be any composition.

The reaction temperature is usually preferably about -10 ° C to room temperature. The reaction time can be generally completed within about 6 hours.

As a washing method, liquid separation is performed after the completion of the reaction, then water is added and the mixture is stirred and washed, and then is settled and separated. As for the amount of washing water, any effect can be observed with respect to the generated thiophosgene. However, if the amount is less than 1 weight, the liquid separation operation is difficult. The number of times of washing may be once or may be divided into several times.

<Effects of the Invention> Since thiophosgene can be easily produced and purified by using the method of the present invention, a thiophosgene solution that can be used for the next reaction can be supplied without the need for operations such as distillation and purification.

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

Example 1 One round bottom 4 equipped with a stirrer, thermometer and gas injection tube
In a one-necked flask, add perchloromethyl mercaptan (155
g), water (480 g), carbon tetrachloride (240 g) and potassium iodide (0.8 g) were added, and the mixture was stirred at 5 ° C. on an ice bath. To this, sulfur dioxide (100 g) was introduced at 5.0 g / min to cause a reaction, and after the introduction, the mixture was further stirred for 5 hours. Stabilize the reaction solution,
After separation, it was then washed once with water (100 ml).

The obtained thiophosgene solution was subjected to thiophosgene analysis by gas chromatography and iodine ion concentration analysis by ion chromatography.

 Table 1 shows the obtained results.

Examples 2 to 8 In the same apparatus as in Example 1, under the conditions shown in Tables 1 and 2,
The reaction was performed at a temperature of 5 ° C. for 5 hours. After the completion of the reaction, a washing operation was performed.

 Table 1 shows the obtained results.

Example 9 To a solution of thiophosgene in carbon tetrachloride obtained in Example 1 was added sodium salt of phenol (80 g), and the mixture was stirred at room temperature for 3 hours. After the completion of the reaction, the mixture was separated, washed with water and concentrated to obtain crude phenylchlorothioformate (106 g).

This was further distilled under reduced pressure to obtain a pale yellow oil.

Reference Example 1 <Stability of thiophosgene in water> In the same apparatus as in Example 1, thiophosgene (95 g: purity: 98)
%), Water (480 g) and carbon tetrachloride (240 g), and the mixture was stirred at room temperature for 8 hours. Eight hours later, thiophosgene was analyzed by gas chromatography, and the decomposition rate was 0.2%.

Comparative Examples 1 to 4 Reaction was carried out at a temperature of 5 ° C. for 5 hours under the conditions shown in Table 2 using the same apparatus as in Examples 1 to 8. After the completion of the reaction, the washing operation was not performed.

 Table 1 shows the obtained results.

Comparative Example 5 A phenol sodium salt (80%) was added to the thiophosgene solution mixed with impurities obtained in Comparative Example 1 in the same manner as in Example 9.
g) was added and the reaction was carried out to obtain crude phenylchlorothioformate (96 g).

This was further purified by distillation under reduced pressure. As a result, a reddish brown color was generated in the distillate.

Claims (1)

(57) [Claims] 1. Thiophosgene produced by reducing perchloromethyl mercaptan with sulfur dioxide and / or hydrogen sulfide in a mixed solvent of organic solvent and water in the presence of iodide and / or sulfur chloride is separated, and then separated into thiophosgene. A method for producing thiophosgene, characterized by washing with water at least 1 time by weight.