Acetoxylation of benzene to phenyl acetate

Oxidative esterification of arenes with carboxylic acids produces aryl esters, which can be used as precursors to valuable phenol derivatives (Scheme 8.6). Commercial production of phenol involves the aerobic oxidation of cumene to cumene hydroperoxide, followed by conversion to acetone and phenol under acidic conditions (Hock process) [49]. Aerobic acetoxylation of benzene to phenyl acetate provides a potential alternative route to phenol, and Pd-catalyzed methods for this transformation have been the focus of considerable effort. None ofthese methods are yet commercially viable, however. 

As described in Section 8.3.2, Pd and NO cocatalysts mediate the acetoxylation of benzene to phenyl acetate. Nitrobenzene is a common by-product for this reaction. The nitrobenzene to phenyl acetate ratio can be tuned via modification of the reaction condition (Scheme 8.14) [51-55]. The proposed role of NO, in the acetoxylation reaction is to oxidize Pd" intermediates to Pd" species to facilitate the otherwise difficult Ar-X reductive elimination (X = O, N). This hypothesis is supported by the fundamental studies by Campora etal. where they showed that a Pd" center bearing alkyl and aryl groups is oxidized by NO2 to Pd" species at room... 

Acetoxylation of benzene to phenyl acetate can be accomplished using either homogeneous or heterogeneous palladitun catalysts in the liquid phase (Fig. 21) [43-46]. Again high-oxidation-state Pd(IV)... 

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