反应详情

A 1.5 l sulfonating flask equipped with stirrer, condenser, dropping funnel and gas outlet is charged with 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. 178.5 g (1.5 mol) of thionyl chloride are then added dropwise at an internal temperature of 100°-105° C. over a period of 2.5 hours. The reddish clear solution is then refluxed overnight (110°-15° C.). The toluene and the phenol are distilled off in vacuo, the highly viscous residue (271.5 g) is stirred in 300 ml of 7:3 toluene/cyclohexane, and the product is allowed to crystallize overnight. The precipitate is filtered off with suction while cold (10° C.) and washed with 3×50 ml of 73 toluene/cyclohexane. It is 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. customequipped with stirrer, condenser
2. temperatureThe reddish clear solution is then refluxed overnight (110°-15° C.)
3. distillationThe toluene and the phenol are distilled off in vacuo
4. customto crystallize overnight
5. filtrationThe precipitate is filtered off with suction while cold (10° C.)
6. washwashed with 3×50 ml of 73 toluene/cyclohexane
7. customIt is dried at 80° C. in vacuo