Some aspects of homogeneous and two-phase aromatic sulphonation

The two-phase sulphonation of benzene and toluene with concentrated sulphuric acid solutions at 30°C has been studied in a continuous stirred tank reactor (1.06 dm³ capacity). The rates of reaction, as a function of sulphuric acid concentration and the overall mass transfer coefficient times, and the interfacial area per unit volume of the acid phase as a function of agitation speed, have been determined. In homogeneous systems, the kinetic rate constants and the relative rates of sulphonation of a series of aromatic hydrocarbons have been measured in the range of 13–16 mol dm^?3 sulphuric acid. It has been shown that the rates of sulphonation of compounds, with levels of reactivity beyond that of m-xylene, are likely to be affected by diffusional phenomena.