Borate Zirconia Mediated Knoevenagel Condensation Reaction in Water

Knoevenagel condensation of 4-oxo-(4H)-1-benzopyran-3-carbaldehydes, 1,3-diphenyl-1H-pyrazol-4-carboxaldehyde and aromatic aldehyde has been carried out with 3-methyl-1-phenylpyrazolin-5-(4H)-one as condensing agent in moderate to good yields by using Borate Zirconia (B2O3/ZrO2) solid acid catalyst in water medium. In each conversion, the catalyst was successfully recovered and recycled without significant loss in yield and selectivity.