Diethyl Malonate → Diethyl (ethoxymethylene)malonate

Participants

Reaction Steps

A mixture of diethyl malonate (160 g., 1.0 mole), ethyl ortho-formate (148 g., 1.0 mole), acetic anhydride solvent (204 g., 2 moles) and anhydrous zinc chloride catalyst (0.5 g) was heated in an oil bath for 6.5 hr (temperature of contents 104°-113° C). The mixture was then distilled through a short column during 3.5 hr, raising the pot temperature to 124°and yielding 120 ml of distillate. The residue was treated with additional ethyl orthoformate (148 g., 1.0 mole) and acetic and acetic anhydride (204 g., 2.0 moles) and distillation was continued for 3 hr to yield 160 ml of distillate (pot temperature 120°-130°). After standing at 25° for 18 hr the residue was diluted with 250 ml of ether and washed thoroughly with water. The combined extracts were dried over magnesium sulfate and distilled to yield a forerun (26 g.) containing principally diethyl malonate and 156 g. (72%) of ethyl ethoxymethylenemalonate, b.p. 109°-111° (0.9mm) (85% yield based on unrecovered diethyl malonate); NMR (CDCl3): δ 7.62 (s,l,=CH), 4.22 (q. J = 7Hz, 2, CH2), 4.19 (q, J = 7 Hz, 4, CH2), 1.37 (t, J = 7 Hz, 3, CH3), 1.30 (t, J = 7 Hz, 6, CH3).

Provenance & Evidence