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Org. Synth. 1940, 20, 24
DOI: 10.15227/orgsyn.020.0024
DECAMETHYLENE BROMIDE
[Decane, 1,10-dibromo-]
Submitted by W. L. McEwen
Checked by Reynold C. Fuson and E. A. Cleveland.
1. Procedure
A 2-l. three-necked flask, supported in an oil bath, is fitted with a mechanical stirrer and an inlet tube which reaches almost to the bottom of the flask. In it is placed 696 g. (4 moles) of decamethylene glycol, and, after the oil bath is heated to 95–100°, a rapid stream of dry hydrogen bromide is introduced, with stirring. When the mixture becomes saturated with the gas, as shown by vigorous fuming at the open neck of the flask (Note 1), the temperature of the oil bath is raised to 135° and a slow current of hydrogen bromide is passed in for 6 hours (Note 2).
After cooling, the crude product is transferred to a separatory funnel and the lower aqueous layer is drawn off and discarded. The upper layer is washed once with an equal volume of warm water, and then with successive portions of 10% sodium carbonate solution until all acid has been removed. It is then washed once with warm water, which is separated as completely as possible (Note 3). The product thus washed is distilled from a Claisen flask under reduced pressure. The first few drops of distillate containing some water are discarded: the main fraction distils at 139–142°/2 mm. The yield is 1080 g. (90%) (Note 4).
2. Notes
1. In larger runs it is advantageous to stop the stirrer and gas stream at this point and allow the lower aqueous layer to separate, after which it is siphoned out.
2. The total quantity of bromine used is about 950 g.
3. If difficulty is encountered with separation of layers in washing, the substance may be dissolved in an equal volume of ether.
4. This yield was almost invariably obtained by the submitter, who used quantities of glycol varying from 150 g. to 2 kg.
By the same procedure the following dibromides have been prepared.

% Yield

Boiling Point


Trimethylene bromide

75

165–167°

Hexamethylene bromide

90

108–112°/8 mm.

Nonamethylene bromide

93

128–130°/2 mm.


3. Discussion
Decamethylene bromide was first prepared by heating the glycol in a sealed tube with fuming hydrobromic acid.1 Later it was prepared in the manner here described,2,3 and by treating the glycol with hydrobromic acid in the presence of sulfuric acid.4
This preparation is referenced from:

References and Notes
  1. Franke and Hankam, Monatsh., 31, 181 (1910).
  2. Chuit, Helv. Chim. Acta, 9, 264 (1926).
  3. Carothers, Hill, Kirby, and Jacobson, J. Am. Chem. Soc., 52, 5279 (1930).
  4. Price, Guthrie, Herbrandson, and Peel, J. Org. Chem., 11, 281 (1946).

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

sulfuric acid (7664-93-9)

ether (60-29-7)

HYDROBROMIC ACID,
hydrogen bromide (10035-10-6)

sodium carbonate (497-19-8)

bromine (7726-95-6)

Trimethylene bromide (109-64-8)

Decamethylene glycol (112-47-0)

Decamethylene bromide,
Decane, 1,10-dibromo- (4101-68-2)

Hexamethylene bromide (629-03-8)

Nonamethylene bromide (4549-33-1)