Poly(4-vinylpyridine)-supported dual acidic ionic liquid: an environmentally friendly heterogeneous catalyst for the one-pot synthesis of 4,4 -(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols)

A poly(4-vinylpyridine)-supported Brønsted ionic liquid was easily prepared from its starting materials and used as a novel, highly efficient, and reusable heterogeneous catalytic system for the synthesis of 4,4 -(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) from the condensation reaction between aromatic aldehydes and 2 equivalents of 3-methyl-l-phenyl-5-pyrazolone.