Preparation method of high-content thiodicarb

Abstract

The invention discloses a preparation method of high-content thiodicarb, and relates to the technical field of chemical synthesis. The method comprises the following steps: generating methylformamide thiamidine by taking N-methylformamide and sulfur dichloride as raw materials, carrying out condensation reaction on the methylformamide thiamidine and methomyl as raw materials under the action of a catalyst to generate a mixed solution containing thiodicarb, adding water into the mixed solution, conducting cooling to obtain a solution and crystals, filtering the solution and crystals, washing the filtered crystals, centrifugally filtering the crystal and a detergent, and drying the centrifugally filtered crystal to obtain thiodicarb with the content of greater than or equal to 98.0% and the total yield of greater than or equal to 95.0% in terms of methomyl. According to the method provided by the invention, the safety occupational health hazard risk is reduced, the process is safer, the operation is convenient, the use of pyridine is avoided, the foul odor on the production site is avoided, the environmental protection pressure is relieved, the production cost is reduced, the product quality and yield of thiodicarb are remarkably improved, and the thiodicarb reaches the export standard.

Description

technical field [0001] The invention discloses a method, relates to the technical field of chemical synthesis, in particular to a preparation method of high-content thiodicarb. Background technique [0002] Thiodicarb is a broad-spectrum, quick-acting insecticide. As a low-toxic derivative of the highly toxic pesticide methomyl, the development of this variety has important practical significance. At present, the demand at home and abroad is still very strong, and the product market has broad prospects. [0003] At present, there are mainly three methods for synthesizing thiodicarb, one is the trimethylchlorosilane-methomyl method, the source of raw materials is difficult, the product yield is low (about 50% based on methomyl), the cost is high, and it is difficult to industrialize; The second is the hydrogen fluoride-methomyl oxime method. The process is complicated and the cost is high. At the same time, the corrosive gas hydrogen fluoride is used, which has strict requir...

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Problems solved by technology

[0003] At present, there are mainly three methods for synthesizing thiodicarb, one is the trimethylchlorosilane-methomyl method, the source of raw materials is difficult, the product yield is low (about 50% based on methomyl), the cost is high, and it is difficult to industrialize; The second is the hydrogen fluoride-methomyl oxime method. The process is complicated and the cost is high. At the same time, the corrosive gas hydrogen fluoride is used, which has strict requirements on the material of the equipment. It is the methomyl method, which is the main method of industrialized production of thiodicarb at present. There are many shortcomings in this method: such as the use of raw material pyridine, the environment of the production workshop is poor, the smell of pyridine is very unpleasant, the stench is strong, and the pyridine wastewater , pretreatment and biochemical degradation treatment are more difficult and the production cycle is longer, the production efficiency is low, and the content and yield are not high. The content of thiodicarb is about 95%, and the yield is generally only about 80%, and the highest is not more than 85%.

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