The role of the solvent in TS-1 chemistry: active or passive? An early study revisited

The oxidation of n-hexane with hydrogen peroxide, catalyzed by TS-1 in various solvents, is reported. The initial rate of reaction decreases in the order: t-butanol > t-butanol/water > methanol approximate to acetonitrile approximate to water, whereas the reverse trend was observed for the adsorption of n-hexane in the catalyst. A dual function is postulated for the solvent in relation to its effects on kinetics. It assists the sorption/desorption of reagents/products in TS-1 (passive role) and participates in the catalytic cycle, through interactions with polar species involved in it (active role). A mechanistic pathway for the hydroxylation of paraffinic and aromatic C-H bonds is suggested.