A Publication
of Reliable Methods
for the Preparation
of Organic Compounds
Annual Volume
Org. Synth. 1951, 31, 68
DOI: 10.15227/orgsyn.031.0068
Submitted by J. C. Sauer1
Checked by William S. Johnson and H. C. Dehm.
1. Procedure
Into a 3-l. three-necked round-bottomed flask fitted with a mechanical stirrer, dropping funnel, and reflux condenser provided with a calcium chloride drying tube is placed 1260 ml. (approximately 900 g.) of anhydrous ether. Stirring is commenced, and 153.0 g. (0.7 mole) of lauroyl chloride (Note 1) is added rapidly through one of the flask openings. The solution is cooled in ice water, and 70.7 g. (0.7 mole) of triethylamine (Note 2) is added over a period of 10 minutes through the dropping funnel in a fine stream. Stirring is discontinued after 1 hour, and the mixture is allowed to come to room temperature. After 12 to 24 hours, the mixture of decylketene dimer (Note 3) and triethylamine hydrochloride is extracted once with 125 ml. of an aqueous 2% sulfuric acid solution to remove the amine salt.
Procedure A. The wet ether layer is transferred to a 3-l. distillation flask and distilled to remove most of the solvent. The warm oily residue is transferred to a 1-l. beaker and mixed with 500 ml. of 2% potassium hydroxide solution. The mixture is heated on a steam bath for 1 hour with occasional stirring and is then chilled in ice water. The waxy cake which settles out on top of the aqueous suspension is skimmed from the surface and dissolved in a mixture of 400 ml. each of acetone and methanol. The hot solution is filtered through a steam-jacketed funnel and cooled in ice water, and the precipitate is collected on a Büchner funnel with suction. The product is washed on the funnel with cold methanol; after air drying overnight it amounts to 55–65 g. (46–55%), m.p. 62–64°.
Procedure B. The following alternative isolation procedure yields a somewhat purer product. The wet ether layer which has been washed with dilute sulfuric acid to remove amine salt is transferred to a 3-l. distillation flask, 150 ml. of 2% sulfuric acid is added, and the mixture is distilled until nearly all the ether is removed. The hot, oily layer is separated in a separatory funnel and distilled (Note 4). The yield of the fraction distilling at 215–230°/3 mm. is 64–75 g. (54–63%). After recrystallization from 750 ml. of acetone, the laurone weighs 55–65 g. (46–55%), m.p. 68–69° (Note 5).
2. Notes
1. A commercial lauric acid, such as that available from Armour and Company, was converted into the acid chloride by reaction with thionyl chloride. The checkers employed 1 kg. of thionyl chloride for 1201 g. of acid. The product was distilled through a 12-in. Vigreux column, giving 1145 g. (87%) of colorless acid chloride, f.p. −15° to −18°.
2. Triethylamine was purified by the following procedure: fractional distillation, addition of about 2% phenyl isocyanate to the distillate, and redistillation.
3. If desired, decylketene dimer can be isolated at this point by filtering the reaction mixture and concentrating the filtrate. The mixture should be handled at all times under anhydrous conditions. The filtration should be carried out by the inverted filtration method.2 Difficulties are usually encountered in the filtration step since the amine salt frequently separates as a gel. Seeding the ether solution of lauroyl chloride with triethylamine hydrochloride usually aids in preventing this gel formation. It is necessary to rinse the amine salt several times with ether to extract the dimer, which is usually contaminated with traces of triethylamine hydrochloride.
4. The electrically heated fractionating column used by the submitter for distilling laurone is pictured in part in Fig.11. This still, with a column length of 8 in., was designed by Dr. H. J. Sampson of the Rayon Department of E. I. du Pont de Nemours and Company, Inc., Waynesboro, Virginia.
Fig. 11.
Fig. 11.
5. Other acid chlorides of the type RCH2COCl can be similarly dehydrochlorinated. For example, caproyl chloride (1.2 moles) was converted to di-n-amyl ketone, b.p. 98–102°/15 mm., in 60–71.5% yield. In this case, it was found preferable to remove the amine salt from the reaction mixture by washing with 2% sulfuric acid. The butylketene dimer was then extracted from the reaction mixture by washing with 5% sodium hydroxide solution; the alkaline solution was acidified with sulfuric acid and steam-distilled. The oily layer in the distillate was separated and fractionated.
3. Discussion
Laurone has been prepared by hydrating and decarboxylating decylketene dimer.3 It has also been prepared by distilling calcium laurate;4 by heating lauric acid with phosphorus pentoxide;5 by heating barium laurate under reduced pressure;6 by the ester condensation of ethyl laurate with sodium ethoxide7 or of methyl laurate with sodium hydride8 or diisopropylamino-magnesium bromide9 followed by ketonic hydrolysis; by catalytic ketonization of lauric acid over a chromate catalyst;10 or by passing lauric acid over thorium dioxide at 400°.11
This preparation is referenced from:

References and Notes
  1. E. I. du Pont de Nemours and Company, Wilmington, Delaware.
  2. Org. Syntheses Coll. Vol. 2, 610 (1943).
  3. Sauer, J. Am. Chem. Soc., 69, 2444 (1947); Piekarski, J. recherches centre natl. recherche sci., Labs. Bellevue (Paris), No. 40, 197 (1958) [C. A., 52, 19922 (1958)].
  4. Overbeck, Ann., 84, 289 (1852).
  5. Kipping, J. Chem. Soc., 57, 980 (1890).
  6. Krafft, Ber., 15, 1711 (1882).
  7. Strating, Backer, Lolkema, and Benninga, Rec. trav. chim., 55, 903 (1936).
  8. Hansley, U. S. pat. 2,108,156 [C. A., 33, 6342 (1939)].
  9. Frostick and Hauser, J. Am. Chem. Soc., 71, 1350 (1949).
  10. Wortz, U. S. pat. 2,108,156 [C. A., 32, 2542 (1938)].
  11. Pickard and Kenyon, J. Chem. Soc., 99, 57 (1911).

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

sulfuric acid (7664-93-9)

methanol (67-56-1)

ether (60-29-7)

sodium hydroxide (1310-73-2)

thionyl chloride (7719-09-7)

thorium dioxide

acetone (67-64-1)

potassium hydroxide (1310-58-3)

sodium ethoxide (141-52-6)

Triethylamine hydrochloride (554-68-7)

phenyl isocyanate (103-71-9)

ethyl laurate (106-33-2)

lauric acid (143-07-7)

sodium hydride (7646-69-7)

lauroyl chloride (112-16-3)


triethylamine (121-44-8)

12-Tricosanone (540-09-0)


caproyl chloride (142-61-0)


calcium laurate (4696-56-4)

barium laurate (4696-57-5)

methyl laurate (111-82-0)

diisopropylamino-magnesium bromide

phosphorus pentoxide (1314-56-3)

di-n-amyl ketone (927-49-1)