Benzaldehyde → 2,4-Pentanedione, 3-(phenylmethylene)-

Participants

Reaction Steps

2,4-Pentanedione (2, 4.10 ml, 39.2 mmol) and benzaldehyde (1b, 4.06 ml, 40.0 mmol) were stirred in benzene (10 ml). Piperdine (3 drops) and glacial acetic acid (6 drops) were added and the mixture refluxed with a Dean-Stark water trap for 3 hr. The resulting mixture was cooled to room temperature, extracted into ethyl ether, washed with hydrochloric acid (1 N), saturated sodium bicarbonate, hydrochloric acid (1 N) and twice with water. The organic layer was dried over magnesium sulfate, filtered and evaporated to afford an oil. The crude oil was distilled bulb to bulb to give 7.03 g (95%) of a yellow oil; [expected mp 165-167° C.]; 1H NMR: δ 2.24 (s, 3H), 2.38 (s, 3H), 7.35 (s, 5H), 7.45 (s, 1H); 13C NMR: δ 26.5, 31.6, 128.9, 129.6, 130.5, 132.8, 139.6, 142.7, 196.2, 205.3.

Provenance & Evidence