Acetic Anhydride → 3-[2,4-Bis(dimethylamino)phenyl]-3-(1,2-dimethyl-3-indolyl)-4,5,6,7-tetrachlorophthalide

Participants

Reaction Steps

A mixture of 1.55 g (0.0036 mole) of 2-[(1,2-dimethyl-3-indolyl)carbonyl]-3,4,5,6-tetrachlorobenzoic acid prepared in a manner similar to part A of Example 2, 0.58 g (0.0035 mole) of N,N,N',N'-tetramethyl-m-phenylenediamine and ten ml of acetic anhydride was heated to reflux for approximately one hour. After cooling to room temperature, the reaction mixture was poured into 20 ml of 10 percent hydrochloric acid and the mixture then rendered alkaline by the addition of concentrated ammonium hydroxide. The purple solid which separated was collected by filtration, dried, and recrystallized twice from isopropyl acetate to obtain 3-[2,4-bis(dimethylamino)phenyl]-3-(1,2-dimethyl-3-indolyl)-4,5,6,7-tetrachlorophthalide (Formula III: R°=R1 =R2 =R3 =Cl; R=R5 =R6 =CH3 ; R4 =N(CH3)2 ; Y1 =H) which decomposed at 228°-229° C. The mass spectrum showed an m/e at 575 (M+, 4 Cl). A toluene solution of the product spotted on silica gel developed an intense purple-colored image.

Provenance & Evidence