A Publication
of Reliable Methods
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Org. Synth. 1946, 26, 13
DOI: 10.15227/orgsyn.026.0013
[2-Propanone, 1-chloro-3-phenyl-]
Submitted by Warren D. McPhee and Erwin Klingsberg.
Checked by Nathan L. Drake and Marvin Schwartz.
1. Procedure
Warning: Diazomethane is poisonous and explosive.
Twelve grams (0.18 mole) of ground potassium hydroxide is dissolved in 45 ml. of n-propyl alcohol in a three-necked 500-ml. flask set on a steam bath so that the mixture can be warmed. Two necks of the flask are fitted with dropping funnels. A Vigreux fractionating column (25 cm. in length and 12 mm. in diameter) is inserted in the third neck of the flask. The column is connected, through a condenser and adapter, to a filter flask set in ice as the receiver. The side arm of the receiver is fitted with a drying tube. About 1.5 hours is required to dissolve the hydroxide, whereupon an additional amount of alcohol is added to bring the total volume to 50 ml. The solution is then cooled, and 100 ml. of absolute ether is added. Through one dropping funnel is added dropwise 20 ml. of nitrosomethylurethan1 (equivalent to 0.10 mole of diazomethane; (Note 1)). The flask is warmed on a steam bath so that diazomethane distils over with ether while the nitrosomethylurethan is being added. The addition requires about 20 minutes. During this operation more dry ether is added as needed, through the second dropping funnel, until the total volume of ether distillate is 250 ml. When the ether distilling over is colorless, the distillate is transferred to another three-necked 500-ml. flask, equipped with a mechanical stirrer, a dropping funnel, and a condenser. To the stirred solution is added, over a period of 15 minutes, a solution of 6.6 ml. (7.7 g., 0.050 mole) of phenylacetyl chloride in 10 ml. of absolute ether. A copious evolution of nitrogen accompanies this operation.
After standing for 2 hours, the solution of diazoketone is cooled in ice and treated with dry gaseous hydrogen chloride until the passage of the gas no longer causes evolution of nitrogen (Note 2). At the end of this time, the original yellow color of the solution has changed to an orange-red. About 100 ml. of water is slowly and cautiously added to the ether solution in order to cause a separation into two layers. An additional 50 ml. of water is then added to give a more complete separation. The ether layer is then washed with two 50-ml. portions of a 5% solution of sodium carbonate in water. The ether solution is dried with anhydrous calcium chloride or calcium sulfate, the solvent evaporated, and the product distilled. The yield of benzyl chloromethyl ketone, b.p. 133–135°/19 mm. or 96–98°/1 mm., is 7.0–7.1 g. (83–85%) (Note 3) and (Note 4).
2. Notes
1. The yield of diazomethane from nitrosomethylurethan is usually given as 0.005 mole per ml.2 Another method for the preparation of diazomethane has been described.3
2. This usually requires about 25 minutes. In certain runs, the hydrogen chloride caused the deposition of a dark red flocculent solid, which was removed by filtration. The yield was then 5–10% lower. This can apparently be avoided by waiting 2 hours, as directed, and by cooling the solution before the hydrogen chloride treatment.
3. This method is general for chloromethyl ketones. Yields of 75–85% may be obtained using hydrocinnamoyl chloride or diphenylacetyl chloride.
4. Diazomethane is poisonous and explosive.4 The preparation should be carried out in a good hood.
3. Discussion
Benzyl chloromethyl ketone has been prepared by the reaction of diazomethane with phenylacetyl chloride. The method of Clibbens and Nierenstein,5 in which one equivalent of diazomethane is added to the acyl chloride and the chloromethyl ketone obtained directly, could not be duplicated by Bradley and Schwarzenbach6 or by the submitters.
This preparation is referenced from:

References and Notes
  1. Org. Syntheses Coll. Vol. 2, 464 (1943).
  2. Fieser, Experiments in Organic Chemistry, 2nd ed., p. 377, D. C. Heath & Company, Boston, 1941.
  3. Org. Syntheses, 25, 28 (1945).
  4. Bachmann, Organic Reactions, 1, 47 (1942), John Wiley & Sons, New York.
  5. Clibbens and Nierenstein, J. Chem. Soc., 107, 1491 (1915).
  6. Bradley and Schwarzenbach, J. Chem. Soc., 1928, 2904.

Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

calcium chloride (10043-52-4)

hydrogen chloride (7647-01-0)

ether (60-29-7)

sodium carbonate (497-19-8)

nitrogen (7727-37-9)

calcium sulfate (7778-18-9)

potassium hydroxide (1310-58-3)

n-propyl alcohol (71-23-8)

phenylacetyl chloride (103-80-0)

Diazomethane (334-88-3)


hydrocinnamoyl chloride (645-45-4)

2-Propanone, 1-chloro-3-phenyl- (937-38-2)

Diphenylacetyl chloride (1871-76-7)