Efficient dehydration of cinnamaldoxime to cinnamonitrile over H3PO4/Al-MCM-41

Cinnamonitrile was synthesized via the environmentally benign liquid-phase dehydration of cinnamaldoxime over Al-MCM-41 modified with H3PO4. FT-IR experiments with pyridine have indicated that these mesostructured aluminosilicates contain both Brönsted and Lewis acid sites. The catalytic properties of their H3PO4 treated derivatives for dehydration of cinnamaldoxime have been evaluated. An aprotic solvent with a higher dielectric constant was preferred for this transformation. The conversion of cinnamaldoxime to cinnamonitrile increased with increasing the H3PO4 content in the catalysts up to a maximum value of 30% and decreasing if H3PO4 content was higher. The influence of other operating parameters was also investigated.