反应详情

温度

82.5 °C

560 g of 98% sulfuric acid was dropped into 600 g of methoxybenzene. Then, while the stirring was continued, the temperature was raised into 80 to 85° C., reacting for 3 hours. After the reaction, distillation water was added, adjusting the concentration into 55%. Then, the temperature at about 40° C. was gradually cooled. Upon the temperature reached at 20° C., a small amount of a crystalline of p-methoxybenzenesulfonic acid (4-methoxybenzenesulfonic acid), which was provided in advance, was added, generating crystalline deposition of p-methoxybenzenesulfonic acid in the system. The crystalline as obtained was collected by filtering, into which water was added and the liquid temperature was again raised at 40° C. to dissolve. The concentration was adjusted to have 55%. Then, the temperature at about 40° C. was gradually cooled. Upon the temperature reached at 20° C., a small amount of a crystalline of p-methoxybenzenesulfonic acid, which was provided in advance, was added again, generating crystalline deposition of p-methoxybenzenesulfonic acid. The crystalline was collected by filtration so as to obtain methoxybenzenesulfonic acid in which the para compound was included at 98 mole % in the whole of methoxybenzenesulfonic acid.

1. additionwas added
2. concentrationthe concentration into 55%
3. temperatureThen, the temperature at about 40° C. was gradually cooled
4. customreached at 20° C.