Methyl cyclopropyl ketone (CAS no.: ), which is also called as cyclopropyl methyl ketone, could be produced through the following synthesis routes.

A. (CAS no ). A mixture of 450 ml. of concentrated hydrochloric acid, 525 ml. of water, and 384. g. (3 moles) of α-acetyl-γ-butyrolactone and a boiling chip are placed in a 2-l. distilling flask fitted with a 90-cm. bulb-type condenser and a receiver immersed in an ice water bath. dioxide is evolved immediately. ing of the reaction mixture is begun at once, and the temperature is raised at such a rate that the reaction mixture does not foam into the condenser. In about 10 minutes the color changes from yellow to orange to black, the effervescence begins to subside, and distillation commences. The distillation is continued as rapidly as possible. After 900 ml. of distillate has been collected, 450 ml. of water is added to the distilling flask and another 300 ml. of distillate is collected.

The yellow organic layer in the distillate is separated, and the aqueous layer is extracted with three 150-ml. portions of ether. The ether extracts are combined with the organic layer and dried for 1 hour over 25 g. of calcium chloride. A saturated calcium chloride layer forms in the bottom. The ether solution is decanted and dried with an additional 25 g. of calcium chloride. The ether is removed by distillation through a 30-cm. column packed with glass helices and fitted with a total condensation, variable take-off head. The residual crude 5-chloro-2-pentanone weighs 287–325 g. (79–90%). When 290 g. of this material is fractionated through a wrapped 12-in. Vigreux column, the major portion boils at 70–72°/20 mm., n_D²⁵ 1.4371, and weighs 258–264 g. (89–91%).

B. Methyl cyclopropyl ketone (CAS no ). A 2-l. three-necked flask is fitted with a sweep-type stirrer made from -in. iron rod, a reflux condenser, and a 500-ml. dropping funnel. In the flask is placed a solution of 180 g. (4.5 moles) of sodium hydroxide pellets in 180 ml. of water. To this solution is added over a period of 15–20 minutes 361.5 g. (342 ml., approximately 3 moles) of the crude 5-chloro-2-pentanone. If the reaction mixture does not begin to boil during the addition, boiling is initiated by slight heating of the flask and is continued for 1 hour. Three hundred and seventy milliliters of water is then added slowly to the reaction mixture over a 20-minute period, and the mixture is heated under reflux for an additional hour.

The condenser is arranged for distillation, and a water-ketone mixture is distilled until all the organic layer is removed from the reaction mixture. The aqueous layer of the distillate is saturated with potassium carbonate, and the upper layer of methyl cyclopropyl ketone is separated. The aqueous layer is extraced with two 150-ml. portions of ether. The ether extracts and the ketone layer are combined and dried over 25 g. of calcium chloride for 1 hour. The ether solution is decanted and dried with an additional 25 g. of calcium chloride. The dried ether solution is fractionated through the 30-cm. column described in Part A. The yield of methyl cyclopropyl ketone, b.p. 110–112°, n_D²⁵ 1.4226, is 193–210 g. (77–83%).