Chapter 15, Problem 51P

When toluene is sulfonated (concentrated $H_{2}S{O}_4$) at room temperature, predominantly (about 95% of the total) ortho and para substitution occurs. If elevated temperatures (150–200 °C) and longer reaction times are employed, meta (chiefly) and para substitution account for some 95% of the products. Account for these differences in terms of kinetic and thermodynamic pathways. (Hint: m-Toluenesulfonic acid is the most stable isomer.)