Synthesis of 4,4’-(Arylmethylene)bis(1H-pyrazol-5-ols) Using Silica-bonded Ionic Liquid as Recyclable Catalyst

Abstract

N -(3-Silicapropyl)- N -methyl imidazolium hydrogen sulfate ([Sipmim]HSO 4 ) is prepared and employed as a recyclable catalyst for the synthesis of 4,4’-(arylmethylene)bis(1 H -pyrazol-5-ols) from aromatic aldehydes with 3-methyl-l-phenyl-5-pyrazolone in refluxing ethanol. [Sipmim]HSO 4 could be recycled for several times without any additional treatment.