Potassium Hydroxide → Benzylmalonic acid

Participants

Reaction Steps

Diethyl benzylmalonate (100 g, 400 mmol) was dissolved in ethanol (300 mL) and treated with a solution of potassium hydroxide (134.4 g, 2.4 mol) in water (500 mL). The mixture was heated under reflux for 5 hours and then allowed to cool. Ethanol was removed under reduced pressure and the remaining aqueous solution cooled in ice and acidified to pH 1 with concentrated HCl. The product was extracted with ethyl acetate (3×200 mL). The combined extracts were washed with brine, dried over magnesium sulfate, filtered and concentrated under reduced pressure to yield benzylmalonic acid as a white crystalline solid. The solid was taken-up in ethanol (250 mL) and treated portionwise with piperidine (33 g, 397 mmol) followed by an aqueous solution of formaldehyde (37%, 150 mL) which resulted in formation of a white precipitate. The reaction mixture was heated and treated with methanol (50 mL) to give a homogeneous solution. Following dissolution the reaction mixture was heated under reflux for 4 hours. The reaction mixture was concentrated under reduced pressure. The aqueous residue was acidified to pH 1 with 1 M HCl and the product extracted with ethyl acetate (3×150 mL). The combined extracts were washed with brine, dried over magnesium sulfate, filtered and concentrated under reduced pressure to yield 2-benzyl-acrylic acid as a colorless oil which crystallized on standing (45 g, 75%). 1H-NMR; δ (CDCl3), 7.32-7.17 (5 H, m), 6.36 (1 H, s), 5.54 (1 H, d, J=1.3 Hz), 3.61 (2 H, s).

Provenance & Evidence