p-Toluenesulfonic acid → HCID 86743955, compound

Participants

Reaction Conditions

Reaction Steps

A solution of 1.73 g of 1,3,3-trimethyl-2-methylene-pyrrolo[2,3-b]pyridine in 3 ml of acetic anhydride was added to a solution of 1.72 g anhydrous 4-methylbenzenesulfonic acid in 5 ml of acetic anhydride, followed by 3.04 g of 3-formyl-1-phenyl-2-(2-thiophenyl)indole. The resulting mixture was stirred and heated at 135° C. for 1 minute, then was diluted with 60 ml of ethyl acetate and cooled to 0°-5° C. The solid product was collected by suction filtration, washed with ethyl acetate, and was combined with a second amount of solid obtained from concentration of the filtrate to give 6.26 g of damp crystals. Recrystallization from a mixture of 20 ml acetone, 2 ml methanol, and 40 ml ethyl acetate gave 3.88 g (61% theoretical) of dye 2 (absorbance maximum in methanol, 505 nm; absorptivity, 62,200), determined to be 95% pure by high-performance liquid chromatography.

Provenance & Evidence