反应详情

154.1 g (1.0 mol) of 2,4-dihydroxybenzoic acid, 141.2 g (1.5 mol) of phenol, 500 ml of toluene and 1 ml of dimethylformamide are placed in a 1.5 l sulfonating flask fitted with stirrer, condenser, dropping funnel and gas outlet. 178.5 g (1.5 mol) of thionyl chloride are added dropwise over the course of 2.5 hours at an internal temperature of 100-105 C. The reddish, clear solution is then refluxed overnight (110-115 C.). Toluene and phenol are distilled off in vacuo, the highly viscous residue (271.5 g) is stirred in 300 ml of toluene/cyclohexane (7/3) and the mixture is left overnight to crystallize. The precipitate is filtered off with suction under cold conditions (10 C.) and the solid product is washed with 3×50 ml of toluene/cyclohexane (7/3) and then dried at 80 C. in vacuo, to give 125.5 g (54.4% of theory) of phenyl 2,4-dihydroxybenzoate (m.p. 135-137 C.).

1. customfitted with stirrer, condenser
2. temperatureThe reddish, clear solution is then refluxed overnight (110-115 C.)
3. distillationToluene and phenol are distilled off in vacuo
4. customto crystallize
5. filtrationThe precipitate is filtered off with suction under cold conditions (10 C.)
6. washthe solid product is washed with 3×50 ml of toluene/cyclohexane (7/3)
7. customdried at 80 C