Method for preparing isothiocyano methyl formate

Abstract

The invention discloses a method for preparing isothiocyano methyl formate. The method is characterized in that a sodium thiocyanate aqueous solution and methylclhlorofonmate are taken as raw materials, a tubular reactor is adopted, and the isothiocyano methyl formate is synthesized continuously under the action of chloroethylene-supported N-alkyl-N-methylaniline serving as a solid catalyst. By adopting the method, the conventional kettle reaction method is changed. The tubular reactor is used for preparing the isothiocyano methyl formate by continuous synthesis, so that the reaction time is shortened greatly, reaction byproducts are reduced at the same time, side reactions of the isothiocyano methyl formate are avoided, and the reaction safety is enhanced. The chloroethylene-supported N-alkyl-N-methylaniline serving as the solid catalyst is adopted, so that the problem of odor pollution due to entrance of N,N-dimethylaniline serving as a catalyst into subsequent waste water in the conventional method is solved, and the environmental protection stress is lowered. Moreover, the catalyst can be used continuously for 300 hours, so that the production cost is lowered greatly. The method is low in equipment investment, is short in reaction period, is easy to operate, and is suitable for industrial production.

Description

Field of invention: [0001] The invention relates to a preparation method of methyl isothiocyanate. technical background: [0002] Methyl isothiocyanate, as a thioisocyanate compound, is an important intermediate for the synthesis of thiophanate-methyl. Thiophanate-methyl is a broad-spectrum systemic benzimidazole fungicide developed by Nippon Soda Co. Ltd., widely used in wheat, rice vegetables, cotton, melons and fruits, rapeseed, sugar beets, sweet potatoes , flowers and other crops, control wheat smut, scab, rice blast, sheath blight, rape sclerotinia, cotton disease, sweet potato black spot, melon powdery mildew, anthracnose, gray mold, Bean gray mold, pea powdery mildew, brown spot, flower disease, etc., can also be used for textiles, paper, leather, etc. to prevent mildew, rot and preserve fruit. [0003] The chemical structure of methyl isothiocyanate is shown in formula (I): [0004] [0005] At present, the synthetic method of methyl isothiocyanate is mainly b...

AI Technical Summary

Problems solved by technology

[0011] 1. Potassium thiocyanate or sodium thiocyanate has high moisture requirements (except IN184429), and it needs to be dried, which is cumbersome to operate and high in production cost

[0012] 2. Since the reaction is carried out in a reaction kettle with a solvent, and it is an exothermic reaction, it is necessary to slowly add methyl chloroformate dropwise under temperature control conditions, so the reaction time is long, while methyl isothiocyanate takes a long time In the presence of water / high temperature conditions, many side reactions will occur, releasing a lot of heat and gas

Not only affects the reaction yield, but also has certain safety risks

[0013] 3. Due to the large amount of catalyst N,N-dimethylaniline used, the catalyst is easy to enter the subsequent wastewater, which makes the wastewater have a strong odor, which is difficult to remove and seriously affects the environment.

Images