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-dimethylbenzenesul fonic acid (125 - 195 degrees C, 0 - 14.5 m(HCl)) in HCl solutions are investigated. Under our experimental conditions, arenesulfonic acid i s almost completely converted into the hydrolysis products, and in the solutions with a constant HCl concentration, the rate of hydrolysis i s proportional to the concentration of sulfonic acid. The hydrolysis o f arenesulfonic acid proceeds via noncatalytic and catalytic routes. I n the first case, the reactive complex is a hydrate of the neutral for m of sulfonic acid and, in the second, a complex of such a form with a n ionic pair H3O+ Cl-.