Acetic Anhydride → 3,3-Bis(2,4-bis(dimethylamino)phenyl)-5-(dimethylamino)phthalide

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Reaction Steps

A mixture of 2-(2,4-bis(dimethylamino)benzoyl)-4-(dimethylamino)benzoic acid or the 5-(dimethylamino) isomer thereof (10 g.), N,N,N'-tetramethyl-m-phenylenediamine (2.30 g.) and acetic anhydride (50 ml.) was warmed (at 30°-35° C.) during 1 hour. More N,N,N',N'-tetramethyl-m-phenylenediamine (1.15 g.) was added and warming was continued. The mixture was diluted with dilute hydrochloric acid (10%) and ice and filtered. The filtrate was made alkaline. Crystallization of the product from toluene afforded 3,3-bis(2,4-bis(dimethylamino)phenyl)-5-(dimethylamino)phthalide (I: X = Y2 = Y4 = Z5 = (CH3)2N, Z4 = Z6 = Z7 = H) (m.p. 188°-192° C.) or the 6-(dimethylamino) isomer thereof.

Provenance & Evidence