Kinetics of two-phase reduction of aromatic nitro compounds by aqueous solutions of sodium sulphides

Abstract

The kinetics of two-phase reduction of aromatic nitro compounds (e.g. m-chloronitrobenzene, m-dinitrobenzene and p-nitroaniline) by aqueous solutions of sodium monosulphide and sodium disulphide was studied in a mechanically-agitated glass contactor. For p-nitroaniline, the effect of temperature in the range of 333 K to 363 K was studied. Diffusional resistance could be eliminated. The reaction between the dissolved nitroaromatic and sulphide species was found to be first-order with respect to the nitroaromatic concentration and first-order with respect to the sulphide concentration. The value of the activation energy for ρ-nitroaniline was found to be 55.2 kJ mol^-1. The values of the second-order rate constant for a variety of nitroaromatic compounds, which varied by a factor of 150, have been correlated by the Hammett's equation.