Acetyl bromide preparation

The preparation reported here is based on the method of Christie and Rapoport.4 9-Bromo-9-phenylfluorene has also been prepared by a light-initiated reaction of bromine and 9-phenylfluorene in carbon disulfide,2 by addition of phenylmagnesium bromide to fluorene36 followed by treatment with acetyl bromide,5 and by treatment of 9-phenylfluorene with N-bromosuccinimide.6... 

The ester derivative of pyrrolo-benzoxazepine 403 (Scheme 84) has been transformed into ketone 404 with methyl lithium, while ester 406 was synthesized by esterification with acetyl bromide of alcohol 405, prepared by LAH reduction of 403 (1996JMC3435). 

Cadmium bromide is prepared by heating cadmium with bromine vapor. Also the compound can be prepared by the treatment of dry cadmium acetate with glacial acetic acid and acetyl bromide. Alternatively, it may be obtained by dissolving cadmium or cadmium oxide in hydrobromic acid and evaporating the solution to dryness under hehum in an inert atmosphere. 

Triphenylmethyl bromide, m.p. 153-154 °C, may be prepared in a similar manner from triphenylmethanol and acetyl bromide. 

A recent and interesting use of zinc is found in the preparation of keten, the simplest of the ketides, from brom-acetyl bromide.8... 

Note 7. Using freshly prepared acetyl bromide solution made up in analytical grade acetic acid, the absorbances at 280 nm of the digested samples were constant after standing at 20°C for periods up to 30 min. This is contrary to the findings of van Zyl (1978) and Cho (1984), who observed that when freshly prepared reagents were used, the absorbances were not stable over this period. 

A conventional preparation of 2,3-diphenyl-1,3-butadiene involves dehydration of meso-2,3-diphenyl-2,3-butanediol by acidic reagents including acetic anhydride,3-5 acetyl bromide,5 sulfanilic acid,6 and potassium hydrogen sulfate.7 Other procedures have been summarized2 previously. 

The reagent is prepared by reaction of tris(4-aminophenyl)methanol (pararosaniline) with 4,5-dichlorophthalic anhydride followed by bromination with acetyl bromide. 

Interchange of halogen is a means of synthesis of certain acyl halides which cannot be conveniently prepared by other methods. Acetyl fluoride is made from acetyl chloride and sodium hydrogen fluoride in acetic anhydride solution." By passing a stream of hydrogen bromide through oxalyl chloride an 85% yield of oxalyl bromide, (COBr), is obtained. The bromide cannot be made by the action of phosphorus pentabromide on oxalic acid. The method has also been applied to the preparation of acetyl bromide and iodide and other acyl iodides. ... 

The conversion of aliphatic and aromatic acyl halides to a keto nitriles has been effected by heating the halides with dry metallic cyanides, of which cuprous cyanide has given the most satisfactory results (60-87%). The acyl bromides rather than the chlorides ate preferred, at least in the formation of aliphatic compounds. Thus, pyruvonitrile is prepared in 77% yield from acetyl bromide and cuprous cyanide whereas no product is obtained if acetyl chloride is employed. Benzoyl cyanide is made in 65% yield by heating the corresponding acyl chloride with cuprous cyanide. "... 

It is generally prepared by the action of bromine on acetic acid in presence of red phosphorus. Phosphorus pentabromide is formed first, and this reacts with the acetic acid, forming acetyl bromide, as follows ... 

Preparation. The procedure is similar to that given for trityl chloride. In a typical run a mixture of 220.8 g. of triphenylcarbinol, 122.9 g. of acetyl bromide, and 100 ml. of benzene gave bromide melting at 153-154° in 90% yield. 

Borgman, R. J., Smith, R. V., Keiser, J. E. The acetylation of apo-morphine. An improved method for the selective preparation of diacetylapomorphine utilizing trifluoroacetic acid/acetyl bromide. Synthesis 1975, 249-250. 

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