Hydrogen bromide preparation

Anders F, I. Lundt, and C. Pedersen, Reaction of partially benzoylated sugars with hydrogen bromide. Preparation of some deoxyhexofuranoses, Acta Chem. Scand., 30 (1976) 624-626. 

Hydrogen bromide cannot be prepared readily by the action of sulphuric acid on a bromide, because the latter is too easily oxidised by the sulphuric acid to form bromine. It is therefore obtained by... 

Hydrogen bromide may also be prepared by dropping bromine into benzene containing aluminium powder, which acts as a catalyst to the reaction ... 

Hydrogen iodide is prepared in a similar way to hydrogen bromide, by the action of water on a mixture of iodine and violet phosphorus. TTie hydrogen iodide evolved may be collected by downward delivery or may be condensed (b.p. 238 K) it reacts with mercury and so cannot be collected over the latter. 

The hydrolysis of phosphorus tribromide or triiodide is used in the preparation of hydrogen bromide and hydrogen iodide respectively ... 

A solution prepared by dissolving 2 g. of biomine in 100 g. of carbon tetra. chloride is satisfactory. Carbon tetrachloride is employed because it is an excellent solvent for bromine as well as for hydrocarbons it possesses the additional advan. tage of low solubility for hydrogen bromide, the evolution of which renders possible the distinction between decolourisation of bromine due to substitution or due to addition. 

Bromination of methane is exothermic but less exothermic than chlorination The value calculated from bond dissociation energies is AH° = -30 kJ Al though bromination of methane is energetically fa vorable economic considerations cause most of the methyl bromide prepared commercially to be made from methanol by reaction with hydrogen bromide... 

TetrabromobisphenoIA. Tetrabromobisphenol A [79-94-7] (TBBPA) is the largest volume bromiaated flame retardant. TBBPA is prepared by bromination of bisphenol A under a variety of conditions. When the bromination is carried out ia methanol, methyl bromide [74-80-9] is produced as a coproduct (37). If hydrogen peroxide is used to oxidize the hydrogen bromide [10035-10-6] HBr, produced back to bromine, methyl bromide is not coproduced (38). TBBPA is used both as an additive and as a reactive flame retardant. It is used as an additive primarily ia ABS systems, la ABS, TBBPA is probably the largest volume flame retardant used, and because of its relatively low cost is the most cost-effective flame retardant. In ABS it provides high flow and good impact properties. These benefits come at the expense of distortion temperature under load (DTUL) (39). DTUL is a measure of the use temperature of a polymer. TBBPA is more uv stable than decabrom and uv stable ABS resias based oa TBBPA are produced commercially. 

Chemical Properties. Thionyl chloride chemistry has been reviewed (169—173). Significant inorganic reactions of thionyl chloride include its reactions with sulfur trioxide to form pyrosulfuryl chloride and with hydrogen bromide to form thionyl bromide [507-16-4]. With many metal oxides it forms the corresponding metal chloride plus sulfur dioxide and therefore affords a convenient means for preparing anhydrous metal chlorides. 

Tetraacylates are prepared from titanium tetrabromide and excess carboxyUc acid ia an iaert solvent. After solvent removal, the residue is heated to remove hydrogen bromide. 

Commercial manufacture of methyl bromide is generally based on the reaction of hydrogen bromide with methanol. For laboratory preparation, the addition of sulfuric acid to sodium bromide and methanol has been used (80). Another method involves the treatment of bromine with a reducing agent, such as phosphoms or sulfur dioxide, to generate hydrogen bromide (81). 

Ethers. In the presence of anhydrous agents such as ferric chloride (88), hydrogen bromide, and acid chlorides, ethers react to form esters (see Ethers). Esters can also be prepared from ethers by an oxidative process (89). With mixed sulfonic—carboxyhc anhydrides, ethers are converted to a mixture of the corresponding carboxylate and sulfonate esters (90) ... 

Liebbrandt have prepared arecaidine by bromination of methyl jV-methylpiperidine-3-carboxyIate, scission of hydrogen bromide from the resulting bromo-compound (VI) and hydrolysis of the resulting arecoline, but Preobrachenski and Fischer were unable to confirm this observation. 

The required intermediate was conveniently prepared in high yield by treatment of a mixture of 5a- and 5) -6-ketones with bromine in the presence of hydrogen bromide. 

Joly s method (or modifications) is the best procedure for preparing A " -3-ketones and can be extended to the elimination of hydrogen bromide from a-bromo ketones of all types. Rearrangement is sometimes observed but is not often serious. Selectivity can be improved in some instances by lowering the reaction temperature. The method has been found useful for the preparation of A" -3-ketones from 6-halo-A" -3-ketones ... 

Quaternary ammonium salts of pyrrolines 106) can be prepared only indirectly 197). Addition of bromine to l-dimethylamino-4-pentene followed by removal of hydrogen bromide afforded, depending upon the dehydrohalogenation conditions, quaternary bromides derived from either l,2-dimethyl-/f -pyrroline (107) or l-methyl-2-methylenepyrrolidine (108) (Scheme 7). 

In extending this direct method of synthesis, we next investigated the possibility of preparing similarly constituted halides from 2-deoxy-D-arabino-hexose (2-deoxy-D-glucose) (21). The hexose was subjected to a partial anomerization procedure described by Bergmann and co-workers (1). The solid material obtained by this procedure is a mixture of the anomeric forms of 2-deoxy-D-arabino-hexose low temperature p-nitro-benzoylation of the latter in pyridine resulted in a mixture of crystalline, anomeric tetrakis-p-nitrobenzoates in a ratio of approximately 1 1. They were readily separable by fractional recrystallization, and treatment of either with an excess of hydrogen bromide in dichloromethane, or with... 

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