Process for synthetizing 2-thiopheneacetyl chloride

Abstract

The invention relates to a process for synthetizing 2-thiopheneacetyl chloride. The method comprises the following steps: dissolving 2-thiopheneacetic acid in dichloromethane, heating in the presence of nitrogen, dropping thionyl chloride in the state of keeping the system slightly boiling and holding the temperature for 2-3 hours after the dropping is completed; finally, carrying out suction filtration, desolvation and reduced pressure distillation to obtain the product 2-thiopheneacetyl chloride. The process disclosed by the invention has the positive effects that the dichloromethane low in boiling point is adopted as the solvent, so that the desolvation is easy and the product content is not influenced; SO2 and HCl produced in the reaction can be volatilized along with the dichloromethane through keeping a proper reaction temperature, so that the reaction can be fully carried out and the reaction yield is increased; the volatilized dichloromethane is cooled through cold saline and can be recycled after being washed by water; the process is mild in reaction condition, little in catalyst amount and simple; compared with an existing synthesis process, the process disclosed by the invention has obvious economic benefit and environmental benefit and is beneficial to industrial production.

Description

technical field [0001] The invention relates to a synthesis process of 2-thiopheneacetyl chloride, which belongs to the technical field of fine chemicals. Background technique [0002] 2-thiophene acetyl chloride is an important intermediate in organic synthesis, widely used in the synthesis of medicines, especially cephalosporins, such as the synthesis of spectrum antibacterial drugs cephalothin, cefotaxime, and cefoxitin. Structural modification of cephalosporin core 7-aminocephalosporanic acid can improve the antibacterial activity of the drug. [0003] At present, the methods for preparing 2-thiopheneacetyl chloride mainly include the following: (1) Add 2-thiopheneacetic acid and thionyl chloride into a flask, heat it to 40-50°C and keep it warm for 4 hours. Then the reaction liquid is distilled under reduced pressure, After removing excess thionyl chloride and low boilers, continue distillation to obtain 2-thiopheneacetyl chloride. Since the reaction system is acidic ...

AI Technical Summary

Problems solved by technology

This method is difficult to completely remove the solvent during vacuum distillation, resulting in unsatisfactory product content; (3) Chinese patent application 200910046880.5 reports that 2-thiopheneacetic acid is solvent in carbon tetrachloride, in the presence of reducing agent anhydrous sodium sulfite , react with thionyl chloride to generate 2-thiopheneacetyl chloride, the yield is 85%

In this method, the product is not only difficult to completely remove the solvent during vacuum distillation, but also the reaction yield is not ideal.