SYNTHESIS OF CYCLOHEXYL METHYL KETONE

• Place 10.7 g (0.44 mol) of magnesium turnings in a 1-litre three-necked round-bottomed flask, equipped with a sealed stirrer unit, a dropping funnel and a double surface reflux condenser each protected with a calcium chloride guard-tube. 

• Add in one portion a mixture of 10 ml of absolute ethanol and 1 ml of carbon tetrachloride. 

• Allow the reaction, which commences almost immediately, to proceed for about 5 minutes and then add carefully 1 50 ml of sodium-dried ether. 

• Site the flask in a warm-water bath and allow the reaction mixture to reflux gently while a solution of 70 g (0.44 mol) of diethyl malonate in 50 ml of dry ether is added with stirring. 

• On completion of the addition, heat the mixture under reflux for about 3 hours or until all the magnesium has reacted. Then add with vigorous stirring a solution of 58 g (0.4 mol) of cyclohexanecarbonyl chloride in 50 ml of dry ether. 

• Heat the reaction mixture under reflux for 2 hours and then cool and acidify with 50 ml of dilute sulphuric acid. 

• Separate the ether layer and extract the residual aqueous solution with two 50 ml portions of ether. 

• Wash the combined ether extracts with water and evaporate the solvent on a rotary evaporator. 

• To the residue add a solution of 120 ml of glacial acetic acid, 1 5 ml of concentrated sulphuric acid and 80 ml of water and heat under reflux for 5 hours. 

• Cool the reaction mixture, basify by the careful addition of 100 ml of 20 per cent sodium hydroxide solution and extract the solution with four 50 ml portions of ether. 

• Dry the combined ether extracts over sodium sulphate and remove the ether on a rotary evaporator. 

• Distil the crude product at atmospheric pressure through a short fractionating column. 

• The yield of cyclohexyl methyl ketone of b.p. 178-1 80 °C is 35 g (70%).