Solvent-Free Knoevenagel Condensation over Cobalt Hydroxyapatite

Abstract

The Knoevenagel condensation between various aldehydes (benzaldehyde, 1-naphthaldehyde, p-bromobenzaldehyde and p-methoxybenzaldehyde) and esters (ethylcyanoacetate, ethylacetoacetate and diethylmalonoester) was carried out under solvent free condition in the presence of cobalt hydroxyapatite (CoHAp), as a catalyst. Good to excellent yields (35–96%) were obtained. The catalyst is found to be superior over fluorapatite and several other heterogeneous catalysts. The catalyst can be recycled at least 3 times.

Keywords:

• Cobalt hydroxyapatite
• environment friendly
• Knoevenagel condensation
• solvent-free condition

ACKNOWLEDGMENTS

This research has been supported by a grant from National Research Foundation and the University of KwaZulu Natal, Durban-Westville Campus. Manoharan Karuppiah Pillai thanks the National Research Foundation and the University of KwaZulu Natal for postdoctoral bursary.

Notes

Yields are in mol %; time is in minutes.