Benzaldehyde → Benzoic acid, 2,2'-((1,3-dioxo-2-(phenylmethylene)-1,3-propanediyl)diimino)bis-

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Reaction Steps

2,2'-[(1,3-Dioxo-1,3-propanediyl)diimino]bisbenzoic acid (1.0 g) and benzaldehyde (0.46 g, 1.5 mol equivalent) were heated under reflux in dry pyridine (8 ml) for 16 hours. After removing pyridine, the mixture was treated with water, made alkaline with 10% aqueous ammonia under ice cooling, and the aqueous layer was washed with ether. The aqueous layer was made acidic (pH=2) with 1N HCl, and the precipitated crystals were collected by filtration. After washing with water, the resulting solid was purified by dissolving in tetrahydrofuran, adsorbing on the silica gel column and separating the desired compound using a developing solvent [ethyl acetate:benzene=1:1 (containing 1% acetic acid)]. After removing the initially eluted impurities, the solvent was removed from the effluent out liquid containing the desired compound. The residue was crystallized by adding water, collected on a filter, washed with water, and dried to give the title compound (0.686 g, yield, 51%), which was recrystallized from the mixed solvent of CH3OH--H2O system to obtain pale yellow crystals of monohydrate (Crystal a, 0.507 g) (Drying: 1 mm Hg, 100° C., 15 hours), m.p., 195°-196° C.

Provenance & Evidence