Two Phase Nitration of Chlorobenzene in 79.8% Sulphuric Acid

It has been previously shown (1) that with 70.2 wt % sulphuric acid and low concentrations of nitric acid the two phase nitration of chlorobenzene in a stirred batch reactor is kinetically controlled. This is because under these conditions k2[HNO3] is very much less than a'k, k2 being the second order rate constant for homogeneous nitration in the acid phase, [HNO3] the acid phase concentration of nitric acid, a' the interfacial area per unit volume of the acid phase and k the overall mass transfer coefficient. As the sulphuric acid strength is raised, the value of k2 increases rapidly (2). Before long k2[HNO3] becomes greater than a'k and transition from kinetic to mass transfer control occurs (3). The present investigation was undertaken with the object of obtaining data with which to check theoretical predictions concerning the nitration rate under mass transfer controlled conditions. A stirred cell was employed