Hydrochloric Acid → Methyl 3-oxovalerate

Participants

Reaction Steps

51.7 g (0.2 mol) of acetoacetic acid methyl ester magnesium enolate in 750 ml of tetrahydrofuran was suspended under nitrogen, 24.3 g (0.24 mol) of triethylamine was added and 38.9 g (0.408 mol) of propionyl chloride was instilled in 15 minutes. The reaction mixture was refluxed for 2 hours, cooled with ice water and hydrolyzed with 285 ml of 1 N HCl. The phases were separated and the water phase was extracted with tert-butyl methyl ether. The organic phases were combined and 140 ml of 10 percent ammonia solution was added with vigorous stirring within 15 minutes. After 1 hour, the phases were separated, dried with sodium sulfate and concentrated by evaporation. The residue was distilled with a Spaltrohr column (split-tube column) at 100 mbars. There was a yield of 23.9 g of 3-oxovaleric acid methyl ester with a purity of 96.0 percent, corresponding to 44 percent of theory. The acetoacetic acid methyl ester separated as the first runnings was able to be used again. The yield thus increased, relative to reacted acetoacetic acid methyl ester, to 69 percent. The boiling point of the product was 109° to 111 C./100 mbars.

Provenance & Evidence