4-氯-3-乙基-1-甲基-5-吡唑羧酸的合成研究

In this paper, the synthetic method of 4-chloro-3-ethyl-1-methyl-pyrazole-5- carboxylic acid (4) was reported from 3-ethyl-5-pyrazolecarboxylate (1) by methylation, chlorination, hydrolytic acidification. In methylation, 3-ethyl-1-methyl-5-pyrazolecarboxylate (2) was prepared by using atoxic dimethyl carbonate (DMC) instead of highly toxic dimethylsulfate. The intermediates 4-chloro-3-ethyl-1-methyl-5-pyrazolecarboxylate (3) was obtained by electrolytic chlorination instead of environmentally unfriendly reagents sulfuryl chloride. This method gets the advantages of simple work-up procedure, milder conditions, which is a green synthetic route.