Heteropoly acid catalysts for the synthesis of fragrance compounds from biorenewables : the alkoxylation of monoterpenes.

Abstract

The cesium salt of tungstophosphoric heteropoly acid, Cs2.5H0.5PW12O40, is an active and environmentally friendly solidacid catalyst for the liquid-phase alkoxylation of widespread monoterpenes, such as camphene, limonene, a-pinene, and bpinene. These reactions provide isobornyl or a-terpenyl ethers, useful as fragrances, in good to excellent yields. The reactions are equilibrium-controlled and occur with high catalyst turnover numbers (TONs) up to 1500–4200 without catalyst leaching. Heteropoly acid H3PW12O40 also efficiently catalyzes the alkoxylation of these monoterpenes under homogeneous conditions with TONs up to 1500–11 300.