Alcohol oxidation structure/reactivity relationships

The efficiency of oxidation of open-chain alkyl, cycloalkyl, and unsaturated alcohols in acetonitrile by 9-phenylxanthylium ion (PhXn+) was dependent on the alcohol stmc-tures. Structure-reactivity relationship was discussed with relation to formation of a carbocationic transition state (C +-OH). Kinetic isotope effects determined at a-D, p-D3, and OD positions for the reaction of 1-phenylethanol suggested a hydride-proton sequential transfer mechanism that involved a rate-limiting formation of the a-hydroxy carbocation intermediate. Unhindered secondary alkyl alcohols were selectively oxidized in the presence of primary and hindered secondary alkyl alcohols. Strained C(7)-C(ll) cycloalkyl alcohols reacted faster than cyclohexyl alcohol, whereas the strained C(5) and C(12) alcohols reacted slower. Aromatic alcohols were oxidized efficiently and selectively in the presence of aliphatic alcohols of comparable steric requirements. ... 

The transfer and the adsorption are strongly influenced by the size of the compound (surface and volume) and by the functional groups present in the molecule (alcohols, aldehydes, ketones, carboxylic acids, amines, mercaptans, halogenated molecules) inducing some polarization effects. Some studies have reported a quantitative structure activity relationship (QSAR) between molecular structure and adsorption parameters (adsorption capacities, energies) [32,37,78]. The reactivity of some compounds leads to oxidation at the adsorbent surface, which plays a catalytic role. Moreover, a mixture of molecules in air... 

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