Oxidation of Alcohols with H2O2 Catalyzed by Titanium Silicalite-1

Primary and secondary alcohols are oxidised by H2O2 in the presence of titanium silicalite-1 to carbonylic compounds. Reaction rates follow the general trend secondary > primary > methanol. Rates are sensitive to position effects of the OH group, to chain branching effects, and to molecular size of the alcohol. Kinetic orders with respect to H2O2 are generally close to zero, while those with respect to the alcohol are strongly affected by the solvent used. The kinetic pattern is interpreted in terms of an interaction of the lattice titanium atom of titanium silicalite-1 with H2O2. The kinetic order with respect to the alcohol can be interpreted either in terms of titanium-alcohol adducts or with a selective alcohol sorption in the catalyst pores. The reaction pattern is consistent with a process taking place essentially inside the zeolite channels, with a transition-state-restricted shape-selectivity. The nature of the titanium hydroperoxide involved in the intermediate complex is discussed.