Application of a multi-SO3H Brønsted acidic ionic liquid in water: A highly efficient and reusable catalyst for the regioselective and scaled-up synthesis of pyrazoles under mild conditions.

An elegant and efficient procedure with exceptionally mild conditions for the regioselective synthesis of pyrazoles by the reaction of various 1,3-diketones and hydrazines/hydrazides using a multi-SO3H Brønsted acidic room temperature ionic liquid as a powerful catalyst in aqueous media has been developed. The ionic liquid was easily separated from the reaction mixture and was recycled and used for at least six consecutive runs without any loss of activity