Catalytic oxidations of alcohols - Advances in Catalytic Activation of Dioxygen by Metal Complexes - page 123

Chapter 3
Catalytic oxidations of alcohols
R.A. Sheldon and I.W.C.E. Arends
Biocatalysis and Organic Chemistry, Delft University of Technology, Julianalaan 136, 2628 BL
Delft, The Netherlands
Abstract : The scope and mechanisms of catalytic methodologies for the selective oxidation
of primary and secondary alcohols, using dioxygen, hydrogen peroxide or alkyl
hydroperoxides as the stoichiometric oxidant, are critically reviewed Emphasis is placed on
homogeneous transition metal catalysts. Catalytic oxidations with dioxygen generally involve
late transition elements, e.g. Ru, Pd and Cu that operate via elimination from a low-
valent alkoxymetal intermediate (hydridometal mechanism) as the key step. In contrast,
catalytic oxidations with hydrogen peroxide and alkyl hydroperoxides generally involve early
transition metals, e.g. Ti, Mo, W and Re, and high-valent peroxometal complexes or first-row
elements (V, Mn and Cr) and high-valent oxometal species as the active oxidant, respectively.
Ruthenium forms an exception in that it is able to catalyze the aerobic oxidation of alcohols
via a hydridometal or an oxometal mechanism.
Keywords : Alcohol oxidations, peroxometal pathway, oxometal pathway, hydridometal
pathway, ruthenium catalyzed oxidations, palladium catalyzed oxidations, copper catalyzed
oxidations, hydrogen peroxide, tert -butyl hydroperoxide, dioxygen
1. INTRODUCTION
The catalytic aerobic oxidation of alcohols has a long history dating
back to Döbereiner's observation, in 1820, that ethanol is oxidized to acetic
acid over platinum black i . Indeed, this preceded the coining of the term
catalysis, by Berzelius in 1835 1 . The catalytic effect of platinum on the
aerobic oxidation of cinnamyl alcohol was described by Strecker in 1855 ii
and in the period 1912-1921 Wieland showed that finely divided palladium
catalyzes the aerobic oxidation of primary alcohols to aldehydes in aqueous