An efficient green approach to aldol and cross-aldol condensations of ketones with aromatic aldehydes catalyzed by nanometasilica disulfuric acid in water

Aldol and cross-aldol condensations of aromatic aldehydes with various ketones in the presence of nanometasilica disulfuric acid (NMSDSA) as heterogeneous catalyst are presented. The catalyst was prepared according to the developed earlier method using inexpensive and readily available starting materials. The highly active catalyst gave excellent yields of the desired aldol products without self-condensation reaction taking place. Reaction times were short, the procedure and work-up were simple, and no volatile or hazardous organic solvents were involved. The catalyst could be recovered three times with only slight reduction in activity.