Synthesis method of captan or folpet

Abstract

The invention discloses a synthesis method of captan or folpet, which comprises the following steps: uniformly mixing 1, 2, 3, 6-tetrahydrophthalimide or phthalimide, perchloromethyl mercaptan, an organic solvent and a catalyst to obtain a mixture a; or uniformly mixing 1, 2, 3, 6-tetrahydrophthalimide or phthalimide, an organic solvent and a catalyst to obtain a mixture b; dropwise adding an inorganic alkali aqueous solution into the obtained mixture a, and after dropwise adding, carrying out heat preservation for reaction to synthesize captan or folpet; or respectively dropwise adding perchloromethyl mercaptan and an aqueous solution of inorganic alkali into the obtained mixture b, and carrying out heat preservation and reaction after dropwise adding is completed, so as to synthesize captan or folpet. The organic solvent, the catalyst and the water are introduced at the same time, the operation mode is optimized, excessive contact of the raw materials, the product and alkali is reduced, decomposition of the raw materials and the product is reduced, the product yield is increased, the wastewater amount is greatly reduced, the environmental protection requirement is greatly reduced, and the environmental friendliness is greatly improved.

Description

technical field [0001] The invention relates to a synthesis method of captan or folpet, in particular to a synthesis method of captan or folpet with simple and reliable operation, less waste water generation and low equipment dependence, and belongs to the technical field of chemical synthesis. Background technique [0002] Captan, the common name is Captan, also known as Captan, the chemical name is N-(trichloromethylthio)-cyclohex-4-ene-1,2-dicarboximide, which is produced by Chevron Chemical Company A low-toxic, broad-spectrum organosulfur fungicide developed in common use has good control effects on various diseases of wheat, rice, corn, cotton, vegetables, fruit trees, melons, tobacco and other crops. Captan is still a best-selling fungicide until now, and its chemical structural formula is as follows: [0003] [0004] Folpet, chemical name N-trichloromethylthiophthalimide, other names Felton, Falton, Bencapton, is a derivative of phthalimide, It belongs to trichl...

AI Technical Summary

Problems solved by technology

[0008] 1. The raw material 1,2,3,6-tetrahydrophthalimide or phthalimide, sodium hydroxide and alkali need to form a salt first, and there will be 1,2,3 , Alkaline hydrolysis of 6-tetrahydrophthalimide or phthalimide, and the reaction system has been in an alkaline environment during the reaction, which will cause the raw materials and continuously generated products to be in the reaction process Alkaline hydrolysis occurs, resulting in a reduction in product yield;

[0009] 2. In order to avoid excessive alkaline hydrolysis of raw materials and products, high-concentration lye cannot be used, only low-concentration lye can be used, which will inevitably produce a large amount of waste water and put a greater pressure on environmental protection;

[0010] 3. Captan and folpet are hydrophobic, so general stirring cannot be used in the preparation process, and a high-speed homogeneous mixer must be used for strong mixing. However, this kind of mixing equipment is expensive and easy to damage, and it also produces more problems due to the fragility of the equipment. Large instability, which in turn leads to poor process stability, unstable product quality and yield, high dependence on equipment, and high maintenance costs

[0011] 4. The reaction solution obtained during the reaction is a solid-liquid two-phase, unreacted raw materials and other impurities will be precipitated from the water phase and adhere to the product, especially perchloromethanethiol, which has a strong odor and high toxicity, and remains in the The product will cause unqualified products and heavy odor, which will cause workers to be unable to operate during post-processing and filtration, and the quality of the obtained products will be low, thus affecting industrial production

The product yield of fendan synthesized by this method is 83-85% through experiments, and the product purity is 96%. Although the product purity is improved after the introduction of organic solvent, the raw material phthalimide of fendan is sensitive to alkali. When the solution enters the lye, a large amount of alkaline hydrolysis will first occur, and the reaction system is not homogeneous, and the main reaction is difficult, resulting in a low yield of the product

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