Synthesis of 1-(4-Chlorophenyl)-3-hydroxypyrazole

As an important intermediate of pesticides,1-(4-Chlorophenyl)-3-hydroxypyrazole could be synthesized by the cyclization and oxidation from the raw material 4-chlorophenylhydrazine in on-pot method. The process and the influences of factors on the yield were studied,such as cyclization reagents,cyclization catalyst,the ratio of cyclization reagents and the cyclization catalyst,oxidation temperature and oxidation time. The structure was confirmed by IR and 1H NMR. Under the optimal condition,the total yield was 82. 4% based on 4-chlorophenylhydrazine. The process exhibited mild reaction conditions and high yield,and was suitable for industrial production.