Chlorosulfonic acid → HCID 13041924, compound

Participants

Reaction Conditions

Reaction Steps

A three-liter, 3-neck flask equipped with a condensor and drying tube, magnetic spin-bar, thermometer and temperature controller was charged with 48.9 grams (0.2 mol) of the 3-(4'-chlorophenyl)phthalide of Example 1 and with chlorosulfonic acid (1467 ml--about 30 ml/gram of reactant). The resulting dark-purple mixture was stirred and heated at about 70° C. for about 21/2 hours. The mixture was subsequently added, dropwise, over a period of about 21/2 hours, to a stirred ice-water mixture in order to decompose the chlorosulfonic acid. 3 Kg of ice were initially present in the mixture, and an additional 9.5 Kg of ice were added during the dropwise addition. The solid precipitate formed was recovered by filtration, dissolved in dichloromethane (1000 ml), the solution dried over Na2SO4, filtered, diluted with hexane and concentrated by distillation until buff-colored crystalline needles began to appear. The crystalline solid was recovered by filtration, washed with hexane and dried. As a result of these operations, the desired title compound having an m.p. of 158°-159° C. was recovered in a yield of about 84%.

Provenance & Evidence