Solvent-Free Benzylic Oxidations Using Urea-Hydrogen Peroxide Complex (UHP) under Microwave Irradiation

Abstract

Urea-hydrogen peroxide complex (UHP) has been found to be an efficient oxidizing agent for the oxidation of various alkyl benzenes/naphthalene/tetralin under microwave irradiation in solvent-free conditions.

Key words

alkylbenzenes - urea-hydrogen peroxide complex - ­benzylic oxidations - solvent-free conditions - microwave activation

References

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General Procedure: Substrate (1 mmol) and UHP (15 mmol) were added to a borosil beaker (50 mL). The mixture was stirred properly and then irradiated in a microwave oven for an appropriate time (Table [1] ) at 300 W (monitored by TLC). On cooling at r.t., the product was extracted with CH₂Cl₂ (3 × 15 mL). The combined methylene extracts were washed with H₂O and dried over anhyd Na₂SO₄. The product obtained after removal of the solvent under reduced pressure was crystallized from an appropriate solvent.
UHP was prepared by recrystallizing urea in 30% H₂O₂.

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All reactions were carried out in an unmodified domestic microwave oven BPL BMO 800T having maximum output of 800 W operating at 2450 MHz.

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Paul, S.; Nanda, P.; Gupta, R. Synth. Commun., submitted.