Non-corrosive heteropolyacid-based recyclable ionic liquid catalyzed direct dehydrative coupling of alcohols with alcohols or alkenes

A non-corrosive, recyclable and efficient heterogeneous catalyst based on Keggin-type polyoxometalate, i.e., [NMPH]H₃[SiW₁₂O₄₀] was developed for the direct dehydrative coupling of alcohols with alcohols (or alkenes) to synthesize various polysubstituted olefins in good to excellent yields. Furthermore, this reaction could be scaled up and the catalyst could be used for seven runs without significant loss of activity. The kinetic competition experiment shows that the C–H bond cleavage might be involved in the rate-determining step.