JPH0465064B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] This invention relates to a method for producing chloromethylthiocyanate, which is a very useful compound as an intermediate for fungicides and acaricides. [Prior art and problems to be solved] As a conventional method for synthesizing chloromethylthiocyanate, for example, Japanese Patent Application Laid-Open No. 53-56617 discloses a reaction between bromochloromethane and thiocyanate in the presence of water and an onium salt. A method is disclosed. This method is described as a two-phase reaction in which no organic solvent is used and the raw materials are the same as the organic phase. However, since this conventional method for producing chloromethylthiocyanate does not use a solvent, chloromethylthiocyanate, which cannot be said to be stable against heat, is produced under extremely harsh conditions. become. Therefore, the onium salt as a catalyst is thermally decomposed during the reaction, reducing the catalyst efficiency. Furthermore, the reaction progressed further, and a considerable amount of methylene bisthiocyanate was observed as a by-product. In addition, a considerable amount of impurities, which are thought to be polymers due to thermal rearrangement of thiocyanide, are produced. As a result,
There was a problem that both the yield and purity of chloromethylthiocyanate were significantly reduced. In addition, a general method for synthesizing alkyl thiocyanate is to create a two-phase system in which an amine or a quaternary ammonium salt is present as a phase transfer catalyst in an aqueous solution of an alkyl halide and an alkali thiocyanate, and the alkyl halide is used as a solvent and a reactant. Methods of reaction are known (eg, PW Reeves et al., Synthetic Communication, Vol. 6, No. 7, p. 509 (1976)). However, when the synthetic method of Liebes et al. is applied to bromochloromethane, the chloromethylthiocyanate produced further reacts to produce a large amount of methylene bisthiocyanate, so it cannot be applied here.
Naturally, there is no mention of chloromethylthiocyanate in the report by Liebes et al. As mentioned above, the conventional methods, particularly the method disclosed in Japanese Patent Application Laid-open No. 56617/1983 for the production of chloromethylthiocyanate, were not satisfactory in terms of both yield and purity of the target product. [Means for Solving the Problems] The present invention has been made by focusing on the above-mentioned problems in the prior art. The purpose is to solve the problems of the prior art by performing this while maintaining a reflux state. That is, the problems of the prior art described above are solved by the method for producing chloromethylthiocyanate according to the present invention, which is characterized in that bromochloromethane and thiocyanate are reacted in water and toluene in the presence of an onium salt. be done. Examples of the thiocyanate used in the present invention include alkali metal thiocyanates, alkaline earth metal thiocyanates, and ammonium thiocyanate, which may be used alone or in combination of two or more. Examples of onium salts include phosphonium salts and ammonium salts. [Operation of the invention] In the present invention, the reaction for synthesizing chloromethylthiocyanate is carried out in
Unlike the method of No. 56617, it is carried out in a completely two-phase water-toluene system. The reaction proceeds under relatively mild conditions, and the desired product with few impurities is obtained in the toluene organic phase. Furthermore, in this two-phase system, since the inorganic salts are on the aqueous layer side after the reaction, the product can be separated by only a liquid separation operation and chloromethylthiocyanate can be obtained in high quality. Even when a two-phase system of organic solvent and water is used, the purity of the product is high if an organic solvent with a relatively low boiling point such as chloroform, hexane, or benzene is used, as is clear from the description of the examples below. However, even if the reaction is continued for a long time, only extremely low yields can be obtained. On the other hand, organic solvents with high boiling points such as xylene and chlorobenzene are preferable in terms of reaction time and yield, but are unsuitable for actual reactions in terms of the purity of the product obtained. Among these organic solvents, only toluene gave satisfactory results, and it is presumed that this difference is due to the solubility of the onium salt in these solvents. Therefore, the present invention shows that the desired product can be obtained in high yield and purity by using a toluene-water system using toluene as an organic solvent for the synthesis reaction of chloromethylthiocyanate. This is the first knowledge obtained, and the significance of the invention lies in this point. The present invention will be explained in more detail below with reference to Examples. [Example] 38 g (0.5 mol) of ammonium thiocyanate, 84.2 g (0.65 mol) of bromochloromethane, benzyltriethylammonium chloride 3 as onium salt
g, 15 ml of water, and 150 ml of toluene were placed in a 500 ml Kolben and heated and stirred at 85° C. for 5 hours. 25 after reaction
After cooling to ℃, the toluene layer was separated and further washed with alkali. According to gas chromatographic analysis of the obtained toluene layer, the purity of chloromethyl thiocyanate was 99.5%. Furthermore, when this toluene layer was distilled, the yield was 51.4g (theoretical value).
87.4%), the desired product was obtained. bp65~68℃/
14 mmHg. [Comparative Example] Synthesis reactions in an organic solvent-water system were carried out using various organic solvents other than toluene in the same manner as in the examples. Chlormethylthiocyanate as the obtained target product was measured by gas chromatographic analysis. The results are shown in Table 1 below along with Examples.

〔effect〕

As explained above, according to the present invention, the desired product can be obtained in high yield and purity by synthesizing chloromethylthiocyanate in a toluene-water two-phase system.

Claims (1)

[Claims] 1. A method for producing chloromethylthiocyanate, which comprises reacting bromochloromethane and thiocyanate in water and toluene in the presence of an onium salt. 2. The manufacturing method according to claim 1, wherein the thiocyanate is one or more selected from the group consisting of alkali metal salts, alkaline earth metal salts, and ammonium salts. 3. The manufacturing method according to claim 1, wherein the onium salt is a phosphonium salt. 4. The manufacturing method according to claim 1, wherein the onium salt is an ammonium salt.