Reaction of aldehydes and pyrazolones in the presence of sodium dodecyl sulfate in aqueous media

The environmentally friendly condensation 3-methyl-1-phenyl-5-pyrazolone or 3-methyl-1H-5-pyrazolone with aromatic and aliphatic aldehydes was performed in water at refluxing temperature for 1 h using sodium dodecyl sulfate (SDS) as the surfactant catalyst (5 mol%), giving 4,4'-alkylmethylene-bis(3-methyl-5-pyrazolones) in 78.3%similar to 92.1% yields.