Sonication, primary aromatic amines

Oostdyk TS, Grob RL, Snyder JL, et al. 1995. Supercritical fluid extraction of primary aromatic amines from characterized soil samples comparison with sonication extraction. J Environ Sci Health A30(4) 783-816. 

A comparison of extraction methods for primary aromatic amines including 1,4-phenylenediamine, 2,4-diaminotoluene, benzidine, 4,4 -methylenebis (2-chloroanilme), 3,3 -dimethylbenzidine, and 3,3 -dichlorobenzidine from solid matrices was conducted. Supercritical fluid extraction (SEE) was evaluated and compared with the classical method, sonication extraction (Oost-dyk et al., 1993). 

Oostdyk, T. S., Grob, R. L., Snyder, J. L., and McNally, M. E., Study of sonication and supercritical fluid extraction of primary aromatic amines, Anal. Chem., 65, 596-600, 1993. 

A similar conclusion can be drawn from an unexplained case of sonochemical switching (Fig. 29). The addition of primary aromatic amines to methyl pyruvate produces first the tautomeric imine-enamine condensation product. This step seems to be sonication independent. Under stirring at room temperature, the condensation goes on with the condensation of the enamine with the pyruvic ester to yield a lactone. In contrast, sonication under the same conditions... 

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