Hexamethylene dibromide

Trimethylene dibromide (Section 111,35) is easily prepared from commercial trimethj lene glycol, whilst hexamethylene dibromide (1 O dibromohexane) is obtained by the red P - Br reaction upon the glycol 1 6-hexanediol is prepared by the reduction of diethyl adipate (sodium and alcohol lithium aluminium hydride or copper-chromium oxide and hydrogen under pressure). Penta-methylene dibromide (1 5-dibromopentane) is readily produced by the red P-Brj method from the commercially available 1 5 pentanediol or tetra-hydropyran (Section 111,37). Pentamethylene dibromide is also formed by the action of phosphorus pentabromide upon benzoyl piperidine (I) (from benzoyl chloride and piperidine) ... 

Suberic acid. Prepare hexamethylene dibromide from hexamethy-lene glycol (Section 111,15) according to the procedure described in Section 111,35). Convert the 1 6-dibromohexane, b.p. H4r-115°/12 mm., into hexamethylene dicyanide, b.p. 178-180°/15 mm., by refluxing it with a 20-25 per eent. excess of aqueous - alcoholic sodium cyanide solution (compare Section 111,114), distilling off the hquid under diminished... 

The 7-fluoroheptanecarboxylates were synthesized from hexamethylene dibromide according to the following scheme ... 

When sodium selenide reacts with af-hexamethylene dibromide in alcohol only a small proportion of monomeric ct/cfoselenohexane,... 

Freund applied the method to the synthesis of cycloparaffins. From trimethylenedibromide, trimethylene was prepared, whilst hexamethylene-dibromide yielded hexamethylene in a similar manner. (M., 3, 626 A. Ch., [5], 14, 488.)... 

The product is then poured into water, the oily layer separated and dried over calcinm chloride before fractionating. Most of the liquid distils between 100°—150° and is unchanged chlor-methoxy-propane, while the liquid boiling above 150° is chiefly di-methoxy-hexane, which is next digested under a reflux condenser for three hours with fuming hydro-bromic acid. The dark-coloured product is poured into water, the oily layer extracted with ether, and after removing the ether from the dried extract, the residue is heated in a sealed tube with hydrobromic acid for two hours at 150°—160°. The product is poured into water, extracted with ether, and the dark-coloured hexamethylene dibromide fractionated under reduced pressure (20 mm.). That portion is collected which boils between 125° and 140°. 

To a 50-ml Erlenmeyer flask containing a solution of 0.26 gm of sodium in 20 ml of absolute ethanol is added 1.5 gm (1 mole) of hexamethylenedithiol, followed by the dropwise addition of 2.44 gm (0.01 mole) of hexamethylene dibromide. The reaction proceeds rapidly and the solid polymer separates. The polymer is filtered and the filtrate diluted with water to recover more polymer that separates out. The combined crude polymer precipitates are dissolved in benzene and the polymer is precipitated with methanol. This is repeated again to afford a final 0.26 gm (10%) of polysulfide product (m.p. 71°-76°C) (for infiared spectrum see Fig. 1, Polymer B). 

The heavy colourless dibromide (30 gms.) is now mixed with mete-xylene (30 gms,), and added through a funnel drop by drop to a mixture of sodium (15 gms.) in small pieces, and 70 c.c. of m-xylene. The reaction is vigorous, and if a condenser be fitted to the side-tube of the reaction-flask, the resulting hexamethylene distils over between 70° and 100° this may be refractionated over sodium and that part... 

To a solution of 13.2 g (0.054 mole) of 9-bromofluorene in 200 ml of acetonitrile was added 3.1 g (0.018 mole) of l,6-bis(dimethylamino)hexane. Heat was evolved and solid began to precipitate immediately. After the initial reaction had subsided the mixture was refluxed for 3.5 h on a steam bath. The solid was collected and recrystallized three times from propanol to give 10.66 g (89% of the theoretical yield based on alkylenediamine) of hexamethylene bis(9-fluorenyldimethylammonium) dibromide, as white crystals melting at 188°-189°C. 

A mixture of 4.18 g (0.02 mole) of 2-dimethylaminofluorene and 1.22 g (0.005 mole) of 1,6-dibromohexane was heated at 115°C for 24 h, after which time 10 ml of dry dioxane was added and the mixture refluxed for an additional 37 h. The solid was filtered off washed with hot acetonitrile and twice recrystallized from propanol to give 0.45 g of hexamethylene bis(2-fluorenyldimethylammonium) dibromide, melting at 220°-222°C. 

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