Different N-hydroxyphthalimide (NHPI) derivatives were investigated as catalyst for the aerobic oxidation of alkylaromatics, including cumene, phenylcyclohexane and ethylbenzene, leading to the corresponding hydroperoxides in good yields and high selectivity. The employment of different initiators among a large number of aldehydes, the nature of the solvent and the effect of the temperature, were carefully analysed. The progressive reduction of the solvent-alkylaromatic volumetric ratio was also investigated in order to make the proposed approach suitable for industrial applications. 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 catalysts. In particular, while using aldehydes as initiator, the presence of two or more N-hydroxy moieties on the same molecule seems to be advantageous in order to get better chemical efficiencies respect to molecules bearing a single N-hydroxy group. Bond energy measurements and kinetic data by EPR spectroscopy are also presented as a valid support for explaining the experimental data. The recovery and reuse of the catalyst was obtained through a reversible adsorption onto non-basic amberlyst resins followed by its desorption using non-protic polar solvents. The proposed approach seems to be of particular interest for the industrial application. The sunlight photocatalytic oxidation of cumene to hydroperoxide by organic n-semiconductors in presence of NHPI was also investigated.
AEROBIC OXIDATION OF ALKYLAROMATICS TO CORRESPONDING HYDROPEROXIDES CATALYSED BY N‑HYDROXY IMMIDES
MELONE, LUCIO;
2012-01-01
Abstract
Different N-hydroxyphthalimide (NHPI) derivatives were investigated as catalyst for the aerobic oxidation of alkylaromatics, including cumene, phenylcyclohexane and ethylbenzene, leading to the corresponding hydroperoxides in good yields and high selectivity. The employment of different initiators among a large number of aldehydes, the nature of the solvent and the effect of the temperature, were carefully analysed. The progressive reduction of the solvent-alkylaromatic volumetric ratio was also investigated in order to make the proposed approach suitable for industrial applications. 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 catalysts. In particular, while using aldehydes as initiator, the presence of two or more N-hydroxy moieties on the same molecule seems to be advantageous in order to get better chemical efficiencies respect to molecules bearing a single N-hydroxy group. Bond energy measurements and kinetic data by EPR spectroscopy are also presented as a valid support for explaining the experimental data. The recovery and reuse of the catalyst was obtained through a reversible adsorption onto non-basic amberlyst resins followed by its desorption using non-protic polar solvents. The proposed approach seems to be of particular interest for the industrial application. The sunlight photocatalytic oxidation of cumene to hydroperoxide by organic n-semiconductors in presence of NHPI was also investigated.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
