Novel process for producing thiabendazole

Abstract

The invention discloses a process for producing thiabendazole. The process includes carrying out condensation reaction on lactic acid and o-phenylenediamine in acidic aqueous solution(with, but not limited to, hydrochloric acid); regulating pH (potential of hydrogen) values to obtain 2-alpha-hydroxyl ethyl benzimidazole; placing the 2-alpha-hydroxyl ethyl benzimidazole in a container with acetone and sulfuric acid (but not limited to sulfuric acid, or hydrochloric acid and other inorganic acid and strong acid and weak alkali salt) and carrying out oxidation reaction on the 2-alpha-hydroxyl ethyl benzimidazole and potassium permanganate (but not limited to potassium permanganate, or hydrogen peroxide and organic peroxide); carrying out extraction, desolvation and drying to obtain 2-acetyl benzimidazole; placing the 2-acetyl benzimidazole in a container with glacial acetic acid and carrying out halogenations reaction on the 2-acetyl benzimidazole and bromine (but not limited to, or chlorine and other halogens); drying filter cake to obtain 2-dibromomethane acetyl benzimidazole hydrobromide; carrying out reaction on formamide and phosphorus pentasulfide in a container with ethyl acetate to obtain thioformamide; removing phosphorus pentoxide by means of filter-press by the aid of nitrogen to obtain thioformamide / ethyl acetate solution and carrying out cyclization reaction on the thioformamide / ethyl acetate solution and 2-dibromomethane acetyl benzimidazole; purifying reaction products and regulating pH (potential of hydrogen) values to obtain the thiabendazole with the content higher than or equal to 99%. The acetone and the sulfuric acid in the corresponding container are used as solvents. The glacial acetic acid in the corresponding container is used as a solvent. The ethyl acetate in the corresponding container is used as a solvent. The process has the advantages that the cost can be lowered, risks in the aspects of safety and environmental protection can be reduced, environmental pollution can be abated, and the production efficiency can be improved; integral reaction procedures are carried out at the normal temperatures under the normal pressures, accordingly, reaction conditions are mild, the yield of the reaction at each step is quite stable, and the overall yield measured by the aid of the o-phenylenediamine can reach 75% at least.

Description

technical field [0001] The invention relates to a production process of pesticides, in particular to a production process of fungicides. [0002] technical background [0003] The current production process of thiabendazole is as follows: after bromination reaction with pyruvic acid, reaction with thioformamide, condensation reaction with o-phenylenediamine, and adjustment of pH to obtain thiabendazole. The process yield is low, and the total yield can only reach 48% in terms of o-phenylenediamine; the cost is high, and pyruvic acid is expensive, and it cannot be purchased in China; the process is unsafe and pollutes the environment. At this time, the temperature is required to be above 230°C. Under this temperature condition, o-phenylenediamine is easily oxidized. The whole process needs to be protected by nitrogen gas. Therefore, the whole production process is unsafe, the operation is difficult and dangerous, and it also pollutes the environment. Contents of the inventio...

AI Technical Summary

Problems solved by technology

The process yield is low, and the total yield can only reach 48% in terms of o-phenylenediamine; the cost is high, and pyruvic acid is expensive, and it cannot be purchased in China; the process is unsafe and pollutes the environment. At this time, the temperature is required to be above 230°C. Under this temperature condition, o-phenylenediamine is easily oxidized, and the whole process must be protected by nitrogen gas. Therefore, the entire production process is unsafe, difficult to operate, highly dangerous, and pollutes the environment.