Preparation technology of mercapto-5-methyl-1,3,4-thiadiazole

Abstract

The invention provides a preparation technology of mercapto-5-methyl-1,3,4-thiadiazole, relating to the field of pharmaceutical and chemical technology. The technology comprises the steps of: by taking ethyl acetate as raw materials, performing hydrazine, addition and cyclization reaction on the ethyl acetate to prepare mercapto-5-methyl-1,3,4-thiadiazole, using the reactive solvent in the reaction process of ethyl acetate and hydrazine hydrate, and increasing the hydrazine temperature of the ethyl acetate and hydrazine hydrate to 104-110 DEG C to obtain acethydrazide solution; in the addition reaction of the acethydrazide solution, replacing potassium hydroxide methanol solution with liquid ammonia methanol solution; and in the addition reaction of the acethydrazide and ammonia as well as carbon disulfide, firstly adding the carbon disulfide into the acethydrazide solution, and then adding the liquid ammonia methanol solution. According to the technology, the hydrazine reaction speed can be greatly improved, the hydrazine reaction conversion rate can be improved, the time-saving and energy-saving purposes can be achieved, the production cost of the mercapto-5-methyl-1,3,4-thiadiazole can be lowered, and the yield of the addition reaction can be increased.

Description

Technical field [0001] The invention relates to the technical field of medicine and chemical engineering, in particular to a preparation process of methyl mercaptothiadiazole. Background technique [0002] Methylmercaptothiadiazole is an important intermediate in the production of cefazolin, cefcane, cefazene, oxazolone, cephalosporin, cefparol, cephalosporin BL-S339, cephalosporin furbendazole and other medicines. Methyl mercaptothiadiazole is a light yellow powder. Because of its broad antibacterial spectrum, good absorption, and low side effects, it is especially suitable for oral absorption, so it is widely used in clinical practice. Its structure is as follows: [0003] [0004] The current preparation process of methyl mercaptothiadiazole is obtained by hydrazation, addition, and cyclization of ethyl acetate. The specific steps are as follows: heat ethyl acetate and hydrazine hydrate in an ethanol solution at 60-70°C under reflux After reacting for 5 hours, the ethanol and ...

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Problems solved by technology

But there is following weak point in above-mentioned technique: at first in ethyl acetate and hydrazine hydrate reaction process, use ethanol as reaction solvent, cause reactant concentration to be lower, be unfavorable for reaction to carry out, reduce reaction rate, also need decompression treatment, with Removing the ethanol is time-consuming and energy-consuming; during the reaction, potassium hydroxide needs to be reacted with acetylhydrazide and carbon disulfide to form potassium salt, so the potassium hydroxide used in the reaction needs a large amount of methanol to dissolve, and the price of potassium hydroxide itself is not low , Potassium salt is also soluble in methanol, so some potassium salt will be lost due to dissolution in methanol, so the production cost is high and the pollutant discharge is also more

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