Maximization of the Conversion to m-Toluenesulfonic Acid in Sulfuric Acid Sulfonation

Maximization of the conversion to m-toluenesulfonic acid in liquid-phase sulfonation

“…The methyl group on the benzene ring is ortho and para directing and sulfonation of toluene is reported to result in an isomer distribution of 62% p-, 32% o-, and only 6% m-toluene sulfonic acid (Morrison and Boyd, 1973). This isomer distribution can be qualitatively explained based on electronic and steric considerations (Broyles and Eckert, 1973). The effect of experimental conditions on the product distribution in the liquid-phase sulfonation of toluene has been studied previously by various workers (Holleman and Caland, 1911; Englund et al, 1953;Spryskov, 1960;Cerfontain et al, 1963a).…”

“…Initially it was decided to investigate the effect of the acid concentration, temperature, and reaction time. These are the three factors which were previously found to have a significant effect on the conversion to m-toluensulfonic acid (Broyles and Eckert, 1973). The time of acid addition was fixed at about 20 min.…”

“…The acid to toluene mole ratio was fixed at 1.5 to ensure complete reaction in reasonable reaction time. The time of reaction was varied between 2.7 and 3.7 h. These levels of time coincided with those used by Broyles and Eckert (1973). The temperature was varied between 88 and 100 °C.…”

“…The effect of experimental conditions on the product distribution in the liquid-phase sulfonation of toluene has been studied previously by various workers (Holleman and Caland, 1911; Englund et al, 1953;Spryskov, 1960;Cerfontain et al, 1963a). Later a more extensive investigation was carried out by Broyles and Eckert (1973), who studied the effect of temperature, time of reaction, sulfuric acid concentration, mole ratio of reactants, and time of addition of sulfuric acid on the conversion to m-toluenesulfonic acid and also to total toluenesulfonic acids. Interest in the meta isomer was generated by the potential of increasing the amount of this low yield compound.…”

“…Analytical Procedure Broyles and Eckert (1973) used a spectrophototmetric method for analysis of the products. This method was based on a linear resolution of the absorption spectrum of the product, in terms of the spectra of pure isomers of toluenesulfonic acid, 81.28% H2S04 being used as the solvent.…”