Synthesis of 2-Thiopheneacetyl chloride

2-thiophen acetyl chloride is a kind of important organic synthesis intermediate, is widely used in particularly synthesizing of cephalo medicine of medicine, as synthetic spectrum antimicrobial drug cefoxitin, Cephaloridine, cefoxitin.Cephalosporin mother nucleus 7-amino-cephalosporanic acid is carried out to structural modification, can improve the anti-microbial activity of medicine.

Synthesis Method

The method of preparing at present 2-thiophen acetyl chloride mainly contains following several: (1) adds 2-thiophene acetic acid and sulfur oxychloride in flask, be heated to 40-50 DEG C of insulation reaction 4h. then reaction solution carry out underpressure distillation, remove after superfluous sulfur oxychloride and low-boiling-point substance, continue distillation and be 2-thiophen acetyl chloride.

During due to chloride, reaction system is acid, can make the thiphene ring oxidation in 2-thiophene acetic acid and 2-thiophen acetyl chloride, in vacuum distillation process, has a large amount of product carbonizations like this, thereby product yield is reduced; (2) Chinese patent application 201010227870.4 has reported that 2-thiophene acetic acid is under the existence of tetrachloroethylene solvent, reacts generate 2-thiophen acetyl chloride with sulfur oxychloride.

This method product in the time of underpressure distillation is difficult to all slough solvent, causes product content undesirable; (3) Chinese patent application 200910046880.5 has reported that 2-thiophene acetic acid is solvent at tetracol phenixin, under reductive agent sodium sulphite anhydrous 99.3 exists, reacts generate 2-thiophen acetyl chloride, yield 85% with sulfur oxychloride.This method product in the time of underpressure distillation is not only difficult to all slough solvent, and reaction yield is also undesirable.

In the four-hole boiling flask with mechanical stirring, thermometer, air guide outlet, add 100g 2-thiophene acetic acid; 300g methylene dichloride, stirs and is warming up to 35 DEG C, starts to drip 200g sulfur oxychloride under the protection of nitrogen; within 1.5 hours, drip off insulation reaction 2 hours at this temperature.The methylene dichloride of underpressure distillation remnants, continues 90-95 DEG C of (7mmHg) cuts of distillation collection and obtains 2-thiophen acetyl chloride 99.3g, and yield reaches 88.7%.