Chloroacetone → 3-Hydroxy-2-(2-oxopropyl)-2-cyclohexen-1-one

Beteiligte Stoffe

Reaktionsschritte

To a slurry of powdered K2CO3 (4.34 Kg, 31.4 moles) in chloroform (8.5 l), 1,3-cyclohexanedione (3.5 Kg, 31.2 moles) was added with stirring. To this mixture, at an ice-bath temperature, chloroacetone (2.9 Kg, 28.2 moles based on 90% purity) was added over a 1 hour period under a N2 atmosphere with stirring. The reaction temperature was raised slowly to room temperature and it was then allowed to stay at room temperature for 3 days. As the reaction proceeded, stirring became more and more difficult. Distilled water (2 l) was added slowly and the mixture was then transferred to an aqueous sodium hydroxide solution (1 l 50% NaOH to 6 l H2O) with stirring. Additional water (1 l) and chloroform (1 l) were used to rinse the remainer of the mixture from the reaction flask. The pH of the solution was less than 10 and additional sodium hydroxide (1 l of 50% solution) was added to bring the pH of the solution to approx. 10. After stirring for 20 minutes, the mixture was allowed to settle and the organic layer was separated. The aqueous layer was acidified with conc. hydrochloric acid solution (15 lb) and then ethyl acetate (9 l) was added. The mixture was stirred for 20 minutes, allowed to settle, and the organic layer was separated. This organic layer was washed with brine (2 l), dried over Na2SO4, and the filtrate was concentrated under reduced pressure to yield a brown oily product (approx. 4.5 l ). This material can be crystallized from ether, but may be used directly in the next step without further purification, mp 80°-81° C. (crystals obtained from ether crystallization).

Herkunft & Nachweise