Sodium Carbonate → 3-(Diethylamino)-6-[(2,2-diphenylhydrazinyl)methylidene]-1-cyclohexa-2,4-dienone

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A solution of N,N-diphenylhydrazine hydrochloride (79.5 g, 0.36 mol, from Aldrich, Milwaukee, Wis.) in ethanol (500 ml) was slowly added to a solution of 4-diethylamino-2-hydroxybenzaldehyde (58.0 g, 0.3 mol, from Aldrich, Milwaukee, Wis.) in ethanol (500 ml) in the presence of excess sodium carbonate. The reaction mixture was refluxed until 4-diethylamino-2-hydroxybenzaldehyde was completely reacted in about 30 minutes. The solvent (800 ml) was removed by evaporation. The residue obtained was extracted with diethyl ether and the ether extract was washed with water until the pH of the water reached 7. The organic layer was dried over anhydrous magnesium sulfate, treated with activated charcoal, and filtered. The ether solvent was evaporated. The residue was recrystallized from ethanol to form crystals. The crystals were filtered off and washed with cold ethanol. The product was 4-diethylamino-2-hydroxybenzaldehyde N,N-diphenylhydrazone. The yield of the product was 85 g (78.8%). The melting point of the product was found to be 95.5-96.5° C. (recrystallized from a mixture of 2-propanol and ether in a 10:1 ratio by volume). The 1H-NMR spectrum (100 MHz) of the product in CDCl3 was characterized by the following chemical shifts (δ, ppm): 11.55 (s, 1H, OH); 7.55-6.95 (m, 11H, CH═N, Ph); 6.7 (d, J=8.6 Hz; 1H, 6-H of 1,2,4-subst. Ph); 6.23 (s, 1H, 3-H of 1,2,4-subst. Ph); 6.1 (d, J=8.6 Hz, 1H, 5-H of 1,2,4-subst. Ph); 3.3 (q, J=8.0 Hz, 4H, CH2); 1.1 (t, J=8.0 Hz, 6H, CH3). An elemental analysis yielded the following results in weight percent: C, 76.68; H, 7.75; N, 11.45, which compared with calculated values for C23H25N3O in weight percent of: C, 76.85; H, 7.01; N, 11.69.

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