Tetrachlorophthalic anhydride → 1-Ethyl-2-methyl-3-(2-carboxy-3,4,5,6-tetrachlorobenzoyl)indole

Participants

Reaction Steps

To a stirred suspension of 9.66 g (0.017 mole) of tetrachlorophthalic anhydride and 13.5 g (0.034 mole) of 80 percent active 1-ethyl-2-methylindole in 30 ml of benzene maintained at 0°-5° C. by means of an ice bath, 10.6 g (0.079 mole) of aluminum chloride was added in small increments. The reaction mixture was then maintained at 0° to 5° C. for an additional twenty minutes, allowed to warm to room temperature and stirred overnight. The mixture was transferred to a beaker and triturated successively with hexane, 10 percent hydrochloric acid, and lastly with 5 percent aqueous sodium hydroxide which had been heated to 70° C. The residual oil was filtered, acidified with dilute hydrochloric acid and allowed to stand overnight. On standing, the oil gave way to a solid which was collected by filtration, washed with water and dried to yield 6.8 g of 2-[(1-ethyl-2-methyl-3-indolyl)carbonyl]-3,4,5,6-tetrachlorobenzoic acid (Formula VIII: R0 =R1 =R2 =R3 =Cl; R5 =CH3 ; R6 =CH3CH2 ; Y1 =H), an off white solid melting at 214°-216° C. Analysis by mass spectrum showed m/e peaks at 443 (M+, Cl=35) and 398 (M+ -COOH).

Provenance & Evidence