THE KINETICS AND MECHANISM OF HYDROLYSIS OF 2,4-DIMETHYLBENZENESULFONIC AND 2,5-DIMETHYLBENZENESULFONIC ACIDS IN HYDROCHLORIC-ACID SOLUTIONS

The kinetis and mechanism of hydrolysis of 2,4-dimethylbenzenesulfonic acid (85 - 145 degrees C, 0 - 13.4 m(HCl)) and 2,5-dimethylbenzenesulfonic acid (125 - 195 degrees C, 0 - 14.5 m(HCl)) in HCl solutions are investigated. Under our experimental conditions, arenesulfonic acid is almost completely converted into the hydrolysis products, and in the solutions with a constant HCl concentration, the rate of hydrolysis is proportional to the concentration of sulfonic acid. The hydrolysis of arenesulfonic acid proceeds via noncatalytic and catalytic routes. In the first case, the reactive complex is a hydrate of the neutral form of sulfonic acid and, in the second, a complex of such a form with an ionic pair H3O+ Cl-.