2-Methylbenzenesulfonic acid → 3-Amino-1-(3-chloro-4-bromobenzyl)-pyrazol-5-one

Participants

Reaction Steps

48.8 g of 4-bromo-3-chlorobenzylhydrazine are added dropwise under nitrogen to a solution of 33.2 g of β-amino-β-ethoxyacrylic acid ethyl ester and 1.5 g of toluenesulphonic acid in 150 ml of ethanol. After stirring for a further two hours, the mixture was left to stand and the compound identified above began to crystallise out after four hours. It was filtered off and twice recrystallised from ethanol. Melting point: 145°-146°, 23 g (37%).

Provenance & Evidence