Hydrogen bromide alcohols

Reaction of alcohols with phosphorus tribromide (Section 4 13) As an alternative to converting alco hols to alkyl bromides with hydrogen bromide the inorganic reagent phosphorus tribromide is some times used... 

Linear alpha-olefins are the source of the largest volume of ahphatic amine oxides. The olefin reacts with hydrogen bromide in the presence of peroxide catalyst, to yield primary alkyl bromide, which then reacts with dimethylamine to yield the corresponding alkyl dimethyl amine. Fatty alcohols and fatty acids are also used to produce amine oxides (Fig. 1). 

A considerable amount of hydrobromic acid is consumed in the manufacture of inorganic bromides, as well as in the synthesis of alkyl bromides from alcohols. The acid can also be used to hydrobrominate olefins (qv). The addition can take place by an ionic mechanism, usually in a polar solvent, according to Markownikoff s rule to yield a secondary alkyl bromide. Under the influence of a free-radical catalyst, in aprotic, nonpolar solvents, dry hydrogen bromide reacts with an a-olefin to produce a primary alkyl bromide as the predominant product. Primary alkyl bromides are useful in synthesizing other compounds and are 40—60 times as reactive as the corresponding chlorides (6). 

Hydrogen bromide adds to acetylene to form vinyl bromide or ethyHdene bromide, depending on stoichiometry. The acid cleaves acycHc and cycHc ethers. It adds to the cyclopropane group by ring-opening. Additions to quinones afford bromohydroquinones. Hydrobromic acid and aldehydes can be used to introduce bromoalkyl groups into various molecules. For example, reaction with formaldehyde and an alcohol produces a bromomethyl ether. Bromomethylation of aromatic nuclei can be carried out with formaldehyde and hydrobromic acid (6). 

Acids are used to combine with the ammonia formed. A large excess of alcohol is used, but the amount of water is generally kept small. Catalysts such as hydrogen chloride, hydrogen bromide, and sulfuric acid have been employed (71). 

By passing hydrogen bromide through Lo-butyl alcohol. 

Esters of diphenylacetic acids with derivatives of ethanol-amine show mainly the antispasmodic component of the atropine complex of biologic activities. As such they find use in treatment of the resolution of various spastic conditions such as, for example, gastrointestinal spasms. The prototype in this series, adiphenine (47), is obtained by treatment of diphenyl acetyl chloride with diethylaminoethanol. A somewhat more complex basic side chain is accessible by an interesting rearrangement. Reductive amination of furfural (42) results in reduction of the heterocyclic ring as well and formation of the aminomethyltetrahydro-furan (43). Treatment of this ether with hydrogen bromide in acetic acid leads to the hydroxypiperidine (45), possibly by the intermediacy of a carbonium ion such as 44. Acylation of the alcohol with diphenylacetyl chloride gives piperidolate (46). ... 

The initial series of major tranquilizers consists of alkylated derivatives of 4-aryl-4-hydroxypiperidines. Construction of this ring system is accomplished by a set of rather unusual reactions. Condensation of methylstyrenes with formaldehyde and ammonium chloride afford the corresponding hexahydro-1,3-oxazines (119). Heating these oxazines in the presence of acid leads to rearrangement with loss of water to the tetrahydropyridines. Scheme 1 shows a possible reaction pathway for these transformations. Addition of hydrogen bromide affords the expected 4-bromo compound (121). This last is easily displaced by water to lead to the desired alcohol (122) The side chain (123) is obtained by Friedel-Crafts acylation of p-fluorobenzene with 4-chloro-butyryl chloride. Alkylation of the appropriate arylpiperidinol with 123 affords the desired butyrophenone derivative. Thus,... 

Hydrobrotnic acid converts dihydrocarvone into a hydrobromide, CioHjyOBr, which, when treated with cold alcoholic potash, readily loses hydrogen bromide. Instead, however, of the unsaturated substance, -dihydrocarvone, being regenerated as the result of this decomposition, a remarkable formation of a c /cZopropane ring takes place and carone is produced—... 

Halo-l-benzothiepins 4 can be synthesized by the treatment of 7a-halobenzo[fe]cyclopropa-[e]thiopyran-7-ols 2 with hydrogen bromide and subsequent hydrogen bromide elimination from the 2,4-dihalo-2,3-dihydro-l-benzothiepins 3 by l,5-diazabicyclo[4.3.0]non-5-ene (DBN).9 The alcohols 2 are prepared by Grignard reaction of the corresponding 7a-halobenzo[ft]cyclopropa[c]thiopyran-7-ones l18 and are used for the synthesis without purification. The intermediate dihalodihydro-l-benzothiepins 3 are not isolated due to their thermal lability related and more stable compounds are described in Section 2.1.2.1. 

The same explanation was suggested for a detonation that involved the same alcohol contaminated by 1.4% of hydrogen bromide and 1.1% of ferrous ion. The electrophilic intermediate formed as follows ... 

In one accident, benzyl bromide had been stored on zeolites. The bottle detonated after eight days because of the overpressure resulting from the formation of large quantities of hydrogen bromide. This accident was put down to the Friedel-Crafts reaction (see on p.256) of benzyl bromide, itself catalysed by zeolites. This is an identical behaviour to the one described with benzyl alcohol on p.256. 

Phenylpropiolic acid. This is an example of an aromatic acetylenic acid, and is made by adding bromine to the ethylenio linkage in ethyl cinnamate, and treating the resulting dibromide with alcoholic potassium hydroxide which eliminates two molecules of hydrogen bromide ... 

Benzhydryl bromide (BHB) undergoes solvolysis in aqueous dioxane to produce benzyhydryl alcohol (BHA) and hydrogen bromide. 

During dropwise addition of the bromide to the liquid alcohol, the mechanical stirrer stopped, presumably allowing a layer of the dense tribromide to accumulate below the alcohol. Later manual shaking caused an explosion, probably owing to the sudden release of gaseous hydrogen bromide on mixing. 

See Benzyl chloride Catalytic impurities Benzyl alcohol Hydrogen bromide, Iron... 

Benzyl alcohol Hydrogen bromide, Iron l,2-Bis(chloromethyl)benzene Catalytic impurities See other gas evolution incidents, polycondensation reaction incidents... 

Benzyl alcohol contaminated with 1.4% of hydrogen bromide and 1.1% of dissolved iron(II) polymerises exothermally above 100°C. Bases inhibit the polymerisation reaction. In a laboratory test, alcohol containing 1% of HBr and 0.04% of Fe polymerised at about 150° with an exotherm to 240° C. Formation and iron-catalysed poly-condensation of benzyl bromide seems to have been implicated. See Benzyl bromide Molecular sieve, or Catalytic impurities See Other BENZYL COMPOUNDS, POLYCONDENSATION REACTION INCIDENTS... 

Unexpected formation of the oxoadamantane skeleton is observed during a series of transformations of the alkaloid lycopoline 153 lead tetraacetate oxidation of the alcohol (131) gives a 90% yield of the oxaadamantane (132), which is opened to 133 with boron trifluoride in acetic anhydride and re-cyclized to 132 with aqueous hydrogen bromide. 

Bromoacetic acid has been prepared by direct bromination of acetic acid at elevated temperatures and pressures,2-3-4 or with dry hydrogen chloride as a catalyst 6 and with red phosphorus as a catalyst with the formation of bromoacetyl bromide.6-7-8-9-19 Bromoacetic acid has also been prepared from chloroacetic acid and hydrogen bromide at elevated temperatures 6 by oxidation of ethylene bromide with fuming nitric acid 7 by oxidation of an alcoholic solution of bromoacetylene by air 8 and from ethyl a,/3-dibromovinyl ether by hydrolysis.9 Acetic acid has been converted into bromoacetyl bromide by action of bromine in the presence of red phosphorus, and ethyl bromoacetate has been... 

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