Oxidation of primary alcohols to aldehydes with oxygen catalysed by tetra-n-propylammonium perruthenate

The liquid-phase oxidation of a series of saturated and unsaturated non-allylic alcohols to aldehydes with oxygen or air catalysed by tetra-n-propylammonium perruthenate (TPAP, represented as [(n-Pr)(4)N]RuO4) at 80-110degreesC is shown to proceed with selectivities of 72-91% at 55-80% alcohol conversion. The unsaturated alcohols, such as 9-decenol, 9-octadecenol and beta-citronellol, give the corresponding unsaturated aldehydes without competing double bond attack. The time course of oxidation indicates a complex reaction mechanism. The results on oxidation of a test alcohol, t-Bu(Ph)CHOH, suggest that one-electron processes do not play an important role in the TPAP-catalysed aerobic oxidation of alcohols. (C) 2002 Elsevier Science B.V. All rights reserved.