反应详情

A mixture of 3-methylsulfonyl-4-chloro-5-aminobenzoic acid (3.0 g.; 0.012 mole) and furfural (50 ml.) is heated to 70°-80° C. on a water bath. The water formed during the reaction is azeotropically distilled with the excess furfural at 15 mm Hg. pressure during a one hour period. The reaction mixture is cooled and triturated with carbon tetrachloride (100 ml.) to yield 3.6 g. (90%) of 3-furfurylideneamino-4-chloro-5-methylsulfonylbenzoic acid which melts at 221° C. and is used in Step E without further purification.

1. temperatureis heated to 70°-80° C. on a water bath
2. distillationis azeotropically distilled with the excess furfural at 15 mm Hg
3. temperatureThe reaction mixture is cooled
4. customtriturated with carbon tetrachloride (100 ml.)
5. customto yield 3.6 g
6. custom(90%) of 3-furfurylideneamino-4-chloro-5-methylsulfonylbenzoic acid which melts at 221° C. and is used in Step E without further purification