Acceptor-free dehydrogenation of 4-hydroxy-3-methoxybenzyl alcohol to vanillin over a palladium complex

Pd0 immobilized on surface-functionalized SBA-15 via in situ H2-reduction was demonstrated as a highly efficient acceptor-free dehydrogenation catalyst for the oxidation of 4-hydroxy-3-methoxybenzyl alcohol to vanillin in excellent yield without an additional oxidant in the reaction system. Notably, the reaction medium water could be readily reused without further purification, and the catalyst was highly effective for a variety of alcohols. Moreover, a heterogeneous catalyst could be easily recovered and reused without conspicuous loss of activity indicating excellent potential for industrial application.