Sonochemistry in Biphasic Systems

Ultrasonic cavitation has particularly important effects on biphasic systems, emulsification of immiscible liquid-liquids, particle breakage and dispersion, and surface cleaning in liquid-solid mixtures. These mechanical effects, even if sometimes oversimplified, appear to be understandable and predictable by nonexperts in the field, who exploited them in a variety of heterogeneous reactions. Sonochemistry of biphasic systems then developed rapidly, and synthetic applications were reviewed in recent articles. In many cases, the presence of a phase transfer catalyst becomes unnecessary, and sonication can be considered as a physical substitute to PTC , according to the expression of Ando. a 

2 For a recent book, see Dehmlow, E.V. Dehmlow, S.S. Phase Transfer Catalysis, VCH, Weinheim, 3 Ed., 1993. 

3 For recent reviews, see (a) Preparative Chemistry using Supported Reagents (Laszlo, P. Ed.), Academic Press, London, 1987 (b) Solid Supports and Catalysis in Organic Synthesis (Smith, K. Ed.), Ellis Horwood, Prentice Hall, Chichester, 1992 (c) Loupy, A. Bram, G. Sansoulet, A. New /. Chem. 1992,16, 233-242. 

4 (a) Ando, T. Kimura, T. Advances in Sonochemistry (Mason, T.J. Ed), JAI Press, 1991, Vol 2, pp. 211-251 (b) Loupy, A. Luche, J.L. in Handbook of Phase Transfer Catalysis (Sasson, Y. Neumann, R. Eds.), Blackie Academic Professional, London, 1997, pp. 369-404. 

In this chapter, a number of reactions effected in the presence of a PTC agent are described. For the sake of simplicity, the usual abbreviations were used for these catalysts  

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