Can ultrasound substitute for a phase-transfer catalyst? Triphase catalysis and sonochemical acceleration in nucleophilic substitution of alkyl halides and alpha-tosyloxyketones: synthesis of alkyl azides and alpha-azidoketone

Alkyl halides and alpha-tosyloxyketones afford the corresponding azide deri vatives upon treatment with aqueous sodium azide under triphase catalysis o r ultrasound irradiation conditions. The use of surfactant pillared clay ma terials and sonochemistry has been compared and demonstrated in these nucle ophilic substitution reactions. It appears that the use of a two-phase syst em in conjunction with ultrasound irradiation is the method of choice that precludes the need for a catalyst in such reactions. (C) 1999 Elsevier Scie nce B.V. All rights reserved.