Methyl acetoacetate → Methyl 3-oxooctadecanoate

Participants

Reaction Steps

A dry tetrahydrofuran suspension (2 l) of 228 g (5.7 mol) of 60% sodium hydride was cooled to 0° C., and 1.8 l of a tetrahydrofuran solution of 638 g (5.5 mol) of methyl acetoacetate was added thereto dropwise, followed by stirring at room temperature for 1 hour. To the mixture was added dropwise 1.511 kg (5.5 mol) of palmitoyl chloride at 0 to 5° C. followed by stirring at room temperature overnight. After confirming disappearance of palmitoyl chloride by TLC, tetrahydrofuran was evaporated, and the residue was poured into ice-water and extracted with 2 l of ethyl acetate. Ethyl acetate was evaporated, and the residue was poured into a mixture of 400 g of a 28% methanol solution of sodium methoxide and 1.2 l of methanol. The mixture was heated at 60 to 65° C. for 6 hours while stirring to conduct deacylation. The product was cooled with ice, adjusted to pH 5 with a 10% sulfuric acid aqueous solution, and extracted with ethyl acetate. The ethyl acetate layer was washed successively with a 5% sodium carbonate aqueous solution and a saturated sodium chloride aqueous solution. Ethyl acetate was removed by evaporation, and the resulting crude crystals were recrystallized from methanol to give 858 g (2.75 mol; yield: 50.0%) of methyl 3-oxooctadecanoate (melting point: 45° C.).

Provenance & Evidence