Prins condensation for synthesis of nopol from P-pinene and paraformaldehyde on novel Fe-Zn double metal cyanide solid acid catalyst

The present work describes the novel application of Fe-Zn double metal cyanide complexes as solid acid catalysts for the synthesis of nopol from P-pinene. The series of Fe-Zn double metal cyanide complexes were prepared from aqueous solutions of ZnCl2) and K4Fe(CN)(6)center dot 3H(2)O in the presence of tert-butanol, iso-butanol and n-butanol (complexing agent) and tri-block copolymer EO20PO70EO20 (average molecular weight, 5800; co-complexing agent). The catalysts prepared were characterized by X-ray diffraction, thermal analysis, diffuse reflectance UV-vis and Fr-IR spectroscopy. All the catalysts were found to be active solid acid catalyst for Prins condensation reaction between paraformaldehyde and P-pinene in the synthesis of nopol. Coordinatively unsaturated Zn2+ ions in the framework of Fe-Zn double metal cyanide complexes are found to be possible active sites. (C) 2007 Elsevier B.V. All rights reserved.