Acetic Anhydride → 2-(4-(4-(Butyl(1-methylhexyl)amino)phenyl)-3-cyano-1,5-dihydro-5-oxo-2H-pyrrol-2-ylidene)propanedinitrile

Participants

Reaction Steps

A stirred mixture of the disodium salt of 4-cyano-5-dicyanomethylidene-3-hydroxy-2-oxo-2,5-dihydropyrrole (23 parts) and dry N,N-dimethylformamide (180 parts) was cooled to −5° C. to −10° C. and N-n-butyl-N-(1-methylhexyl)aniline containing -acetic anhydride (27%, 37 parts) was added followed by the dropwise addition of phosphorous oxychloride (26 parts) whilst maintaining the temperature at less than −5° C. The mixture was allowed to warm to room temperature and stirred for 20 hours. The reaction mixture was poured into a stirred mixture of ice and water (400 parts) and acetone (400 parts) was added before filtering off a solid. The solid was washed repeatedly with warm water (40° C.) and then dried at 50° C. to yield 3-(4-(N-butyl-N-(1-methylhexyl)amino)phenyl)-4-cyano-5-dicyanomethylidene-2-oxo-2,5-dihydropyrrole (26.8 parts, 65%). A small sample of this material was slurried in boiling methanol, collected by filtration, washed with methanol and dried at 50° C. to give 3-(4-(N-n-butyl-N-(1-methylhexyl)amino)phenyl)-4-cyano-5-dicyanomethylidene-2-oxo-2,5-dihydropyrrole m.p. 180° C.; λmax (CH2Cl2) 662 nm (εmax 60231); M/Z (EI) 415 (M+, 20%), 400 (15), 372 (12), 344 (100), 288 (33) and 272 (25).

Provenance & Evidence