ROLE OF INTERFACIAL REACTION IN HETEROGENEOUS AROMATIC NITRATION

The previously established mechanism of two-phase nitration has been r evised by proposing an additional mode of reaction, viz., interfacial nitration. The interfacial mechanism involves adsorption of the nitron ium ion at the interface, followed by its reaction with the aromatic s ubstrate present in the interfacial monolayer. The evidence for the pr oposed mechanism is provided by the results of the experiments, conduc ted in this work, on nitration of nitrobenzene. Relative magnitudes of the bulk and the interfacial rates during the nitration of nitrobenze ne have been determined. The effects of interfacial area, concentratio ns of sulfuric and nitric acids, and addition of surfactant and inert diluent in the organic phase on the rate of interfacial nitration are studied. On the basis of the proposed mechanism, plausible explanation s have been provided to the anomalies in the rates of nitration, obser ved under the industrially relevant operating conditions.