Electrosynthesis of 4-chloropyrazolecarboxylic acids

摘要

4-Chlorosubstituted pyrazolecarboxylic acids were synthesized via chlorination of the corresponding acids at the Pt anode in NaCl aqueous solutions under conditions of divided galvanostatic electrolysis. The efficiency of the process depends on the structures of the initial pyrazolecarboxylic acids, particularly, on the donor-acceptor properties of the substituents and on their position in the pyrazole ring. The yields of the 4-chlorosubstituted products of chlorination of pyrazole-3(5)-carboxylic acid, 1-methylpyrazole-5-carboxylic acid, 1-methyl-pyrazole-3-carboxylic acid, 1-ethylpyrazole-3-carboxylicacid, and 1-methyl-3-nitropyrazole-5-carboxylic acid are 92, 93, 69, 80, and 4%, respectively.