Methyl cyanoacetate → 3,6-Dimethyl-2,4-dioxocyclohexanecarbonitrile

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Reaction Steps

To a solution of sodium methoxide (162 grams, 3 moles) in 400 mls of anhydrous methanol is added, dropwise, 276 grams (3.2 moles) of methylcyanoacetate over a period of 1 hour at 60° C. with stirring. The resulting slurry is stirred at 60° C. for 10 minutes, whereupon 288 grams (3.0 moles) of 2-hexen-4-one is added over a 20 minute period. The resulting reaction mixture is stirred and heated at reflux for six hours, whereupon a distillation take-off condenser is affixed to the reaction flask and 240 mls of methanol are removed under reduced pressure (65 mm Hg). The reaction mixture is then cooled to room temperature and poured into 2 liters of water. Toluene (500 ml) is added and the mixture is transferred to a separatory funnel. The aqueous layer is removed and again extracted with toluene (500 mls). To the aqueous solution, 500 mls of 18% HCl are added with external cooling at 25° C., whereupon a solid material precipitates. The solid is filtered, dried and recrystallized from aqueous methanol to afford colorless needles of 3,6-dimethyl-2,4-dioxocyclohexanecarbonitrile (338 grams, 68.3% yield based on 2-hexen-4-one); m.p. 178°-179° C. The resulting product is represented by the following equilibrium mixture: ##STR23##

Provenance & Evidence