N,N-Dimethylaniline → 2-(Bis(4-(dimethylamino)phenyl)methyl)-5-(dimethylamino)benzoic acid

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Reaction Conditions

Reaction Steps

A mixture of 46.0 ml of water, 49.4 g of 70 percent methanesulfonic acid, 14.9 g (0.1 mole) of 4-dimethylaminobenzaldehyde, 16.5 g (0.1 mole) of 3-dimethylaminobenzoic acid and 12.1 g (0.1 mole) of N,N-dimethylaniline was maintained at reflux temperature with stirring for approximately twenty-four hours. After cooling, the resulting solution was added slowly with stirring to a mixture of 700.0 ml of water and 27.0 ml of 50 percent aqueous sodium hydroxide. The resulting solution having a pH of 12.6 was maintained at 60° C. for approximately one hour. Two grams of diatomateous earth was added to the solution and the resulting mixture was clarified by filtration. The hot filtrate was added slowly with stirring to a solution of 100.0 ml of water and 10.0 ml of glacial acetic acid. Glacial acetic acid was added slowly to adjust the pH to 4.9 and stirring was continued for approximately fifteen minutes. The solid which formed was collected by filtration, washed with water and dried at approximately 50° C. in vacuo to obtain 21.4 g of 2-[bis(4-dimethylaminophenyl)methyl]-5-dimethylaminobenzoic acid (Formula II: Y=4-N(CH3)2 ; R=R1 =R2 =R3 =CH3), a pale green-colored solid which melted over the range of 179° to 184° C. After one recrystallization from toluene, the melting point was 210° to 212° C.

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