Preparation method of intermediate of 3-isothiazolinone bactericide

Abstract

The invention relates to a preparation method of an intermediate of a 3-isothiazolinone bactericide. The preparation method comprises the following steps of blending 3,3'-dimethyl dithiodipropionate and a solvent according to a weight ratio of 1: (0.5 to 2), adding a catalyst into the mixture, wherein a weight ratio of the catalyst to 3,3'-dimethyl dithiodipropionate is (0.005 to 0.02): 1, controlling a temperature in a reactor in a range of 0 to 35 DEG C, adding alkylamine into the reactor, wherein a mole ratio of alkylamine to 3,3'-dimethyl dithiodipropionate is (2 to 5): 1, carrying out heat preservation for 1 to 10 hours, filtering, washing and drying to obtain N,N'-dialkyl-3,3'-dithiodipropanamide. The preparation method has the advantages that a sodium alcoholate catalyst is used so that reaction activity is improved; reaction time is shortened; product purity is great than or equal to 96%; and a reaction yield is great than or equal to 93%. Therefore, the preparation method is suitable for industrial production.

Description

technical field [0001] The invention relates to a preparation method of a fungicide, in particular to a preparation method of a 3-isothiazolinone fungicide intermediate. Background technique [0002] The important intermediate in the synthesis of 3-isothiazolinone compounds is N, N'-dihydrocarbyl-3,3'-dithiodipropionamide. The most important of these are N,N'-dimethyl-3,3'-dithiodipropionamide and N,N'-dioctyl-3,3'-dithiodipropionamide. [0003] At present, the synthetic method of N, N'-dimethyl-3,3'-dithiodipropionamide has: [0004] European Patent EP95907 mentions the synthesis of N, N'-dimethyl-3,3'-dithiodipropionamide. Mix dimethyl 3,3'-dithiodipropionate with toluene and methanol, cool to 10°C, pass in monomethylamine gas, control the temperature at 10-20°C, and keep warm at 20°C and stir for 20 After 1 hour, methylamine and methanol were distilled off under reduced pressure to obtain crude N,N'-dimethyl-3,3'-dithiodipropionamide containing impurities. [0005] ...

AI Technical Summary

Problems solved by technology

[0011] The shortcomings of the above-mentioned patented method are: low synthesis yield, long operation cycle, low production efficiency, and a large amount of waste discharge will pollute the environment, which needs to be treated and increases the cost

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