MILD OXIDATION OF ALKYLAROMATICS TO CORRESPONDING HYDROPEROXIDES CATALYSED BY N-HYDROXY DERIVATIVES

The catalytic activity of different N-hydroxyphthalimide (NHPI)1 derivatives was investigated in the oxidation of alkylaromatics, including cumene,2,3 phenylcyclohexane2,4 and ethylbenzene,4,5 leading to the corresponding hydroperoxides in good yields and high selectivity. The employment of different initiators among a large number of aldehydes, together with the nature of the solvent and the effect of the temperature, was carefully analysed. In order to make the proposed approach suitable for industrial applications, the progressive reduction of the solvent-alkylaromatic volumetric ratio was also investigated. In particular, the issue related to the low solubility of the NHPI in less polar reacting mixtures was effectively worked out by the use of more lipophilic molecules bearing N-hydroxy moieties.6 The relevancy of the proposed process is particularly apparent when considering the extremely mild operative conditions. Bond energy measurements by EPR spectroscopy are also presented as a valid support for explaining the experimental data.