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Organic Synthess - McKusick B.C.

McKusick B.C., Boekelheide V., Emmons W.D. Organic Synthess - New York, 1963. - 134 p.
Download (direct link): boekelheide1963.pdf
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4. Use of more catalyst or higher temperature leads to an increasingly vigorous evolution of carbon dioxide.
5. Diphenylcarbodiimide can be stored for several weeks at 0°. At room temperature it gradually solidifies to a mixture of trimer and polymer. The monomer can be separated from the solid by vacuum distillation.
3. Methods of Preparation
Carbodiimides have been prepared by desulfurization of thioureas by metal oxides,* by sodium hypochlorite,4 or by ethyl chloroformate in the presence of a tertiary amine;5 by halogena-tion of ureas or thioureas followed by dehydrohalogenation of the N,N'-disubstituted carbamic chloride;8 and by dehydration of disubstituted ureas using j>-toluenesulfonyl chloride and pyridine.7 The method described above is a modification of that of Campbell and Verbanc.8
4. Merits of the Preparation
This method may be applied to the synthesis of a variety of aryl and alkyl сагссШп^ев.9 Other catalysts may also be used,10 but the especially active one described here is the one most easily obtained. The method is superior to other methods
DIPHENYLCARBODIIMIDE
33
reported in that it provides pure products under very simple and mild conditions, allows the use of readily available isocyanates with or without the use of solvent, and offers extremely easy work-up.
1 Textile Fibers Department and Organic Chemicals Department, E. I. du Pont de Nemours and Co., Wilmington, Delaware.
* W. B. McCormack, this volume, p. 73.
* S. Hiinig, H. Lehmann, and G. Grimmer, Ann. Chem., 679, 77 (1953).
* E. Schmidt and M. Seefelder, Ann. Chem., 571,83 (1951).
* R. F. Coles and H. A. Levine, U.S. Patent 2,942,025 (I960) [C. A., 54, 24464a
(I960)].
•Я. Eilingsfeld, M. Seefelder, and H. Weidinger, Angew. Chem., 72, 836 (I960).
* G. Amiard and R. Неутёз, Bidl. Soc. Chim. France, 1956, 1360.
»T. W. Campbell and J. Verbauc, U.S. Patent 2,853,473 (1958) [C.A., 53,10126e (1959)].
* T. W. Campbell, J. J. Monagle, and V. S. Foldi, J. Am. Chem. Soc., 84, 3673
(1962).
«J. J. Monagle, J. Org. Chem., 27, 3851 (1962).
34
ORGANIC SYNTHESES, VOL. 43
DOCOSANEDIOIC ACID
2 I +
XN'
CO(CH2)8CO
2NaOH H2NNH5
-»- Na0C0(CH2)5C0(CH2)8C0(CH2)5C02Na —--^ НОСОССНгСОгН
Submitted by S. Hunig, E. Lucke, and W. Brenninger.1
Checked by Г. E. Mumford, E. A. LaLancette,
W. J. Middleton, and В. C. McKusick.
1. Procedure
A. 2,2'Sebacoyldicyclohexanone. A solution of 167 g. (1.00 mole) of 1-morpholino-l-cyclohexene2 and 101 g. (139 ml., 1.00 mole) of anhydrous triethylamine in 500 ml. of dry chloroform (Note 1) is put in a 5-1., three-necked, round-bottomed flask equipped with a mechanical stirrer, a dropping funnel, and a reflux condenser. Tubes of calcium chloride are inserted in the open ends of the dropping funnel and reflux condenser. The reaction flask is immersed in a water bath at 35°, and a solution of 120 g. (0.50 mole) of sebacoyl chloride (Note 2) in 200 ml. of dry chloroform is added to the well-stirred reaction mixture over a period of about 1.5 hours. The reaction mixture gradually as-
DOCOSANEDIOIC ACID
35
sumes an orange to red color, and a solid precipitates. The reaction mixture is stirred for an additional 3 hours at 35°, 500 ml. of 20% hydrochloric acid is added, and the mixture is boiled under reflux for 5 hours with vigorous stirring. The reaction mixture is cooled to room temperature, and the chloroform layer is separated and extracted with six 150-ml. portions of water. The washings and the aqueous phase are combined, adjusted to a pH of 5-6 with 25% sodium hydroxide solution, and extracted with five 100-ml. portions of chloroform. The chloroform extracts are combined with the chloroform layer, and the chloroform is removed by distillation on a steam bath. The residue gradually congeals to an oily solid on standing at room temperature under a pressure of 10-50 mm. The yield of crude 2,2'-sebacoyldicyclo-hexanone is 181-192 g. (100-106%) (Note 3).
B. Disodium 7,16-diketodocosanedioate. A mixture of 120 g. (3.00 moles) of sodium hydroxide and 1.4 1. of commercial absolute ethanol is refluxed with mechanical stirring in a 5-1. round-bottomed flask until all the sodium hydroxide is dissolved (about 2 hours). The solution is cooled to room temperature, and a warm solution of the crude 2,2/-sebacoyldicyclohexanone from Step A in 300 ml. of absolute ethanol is added. The mixture is brought to a boil on a water bath or steam bath in the course of about 15 minutes and is then refluxed for 1 hour. Colorless disodium 7,16-diketodocosanedioate separates during the heating. The reaction mixture, now a thick mush, is cooled to room temperature, and the salt is collected on a 25-cm. Buchner funnel and pressed as dry as possible, preferably with the aid of a rubber dam. The moist salt is suspended in 11. of absolute ethanol with mechanical stirring and is then collected on the Buchner funnel as before. After being dried in air, the crude colorless disodium 7,16-diketodocosanedioate weighs 248-255 g. (112-115%, based on 1-morpholino-l-cyclohexene). It is pure enough for the following reduction to docosanedioic acid (Note 4).
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