They were initially interested in utilization of neat nitric acid in the
oxidation of benzyl alcohols under solvent-free condition and microwave irradiation.
However, oxidation of benzyl alcohols with neat nitric acid under microwave
irradiation proved to be unpractical because the reaction mixture scattered. After examining
various metal nitrate reagent systems, the sodium nitrate/p-toluenesulfonic
acid system was found to be the most suitable in terms of cleanness and effectiveness
for the oxidation of benzyl alcohols under these conditions.
(N-Heterocyclic carbene)-Pd (NHC-Pd) has been used as a precatalyst for the
anaerobic oxidation of secondary alcohols. It was reported that the use of this complex
allows for a drastic reduction in the reaction times and catalyst loading, when
compared to the unsaturated counterpart. This catalytic system was compatible with
the use of microwave dielectric heating. Domino Pd-catalyzed oxidation-arylation
reactions of secondary alcohols have also been carried out (Landers et al., 2011).
Pd-catalyzed anaerobic oxidation:
Pd-catalyzed domino oxidation-arylation:
The conversion of a α-hydroxyketones into 1,2-diketones using three different
oxidants under microwave irradiation with good yield (78–94%) was reported by
Mitra et al. (1999).