Oxidation of bromine

The rate-determining step was, therefore considered to be reaction of bromine with peroxyacetic acid to give a species (suggested as bromine acetate)which subsequently and rapidly, brominates. Formation of bromine acetate was believed to take place according to the reaction scheme represented by equilibrium (158) (which is analogous to the mercuric oxide oxidation of bromine) followed by either equilibrium (159), (160) or (161), viz. 

The oxides of bromine and iodine are not numerous, and they are not particularly important. Bromine monoxide, Br20 is obtained by the reaction... 

A. J. Balard,9 in 1821, also prepared hypobromous acid in a similar manner, namely, by the gradual addition of mercuric oxide of bromine water, and thoroughly shaking the mixture after each addition. Further, quantities of bromine and mercuric oxide can be added until the yellow fluid contains between 6 and 7 parts of HOBr per 100 c.c. The mercuric oxide can be replaced by silver oxide, silver or mercuric nitrate, mercuric acetate, etc. The soln. with 6-7 parts of HOBr per 100 c.c. decomposes at 30°, but more dil. soln. when distilled under ordinary atm. press, give a distillate of bromine followed by a straw-yellow fraction which is a dil. aq. soln. of hypobromous acid. The decomposition is not so pronounced if it be conducted at 40° under a press, of, say, 50 mm. of mercury. 

Br21 Ion. The Br2+ cation 329 can be prepared797 by oxidation of bromine by S206F2 in the superacid HSO3F—SbF5—3S03 however, even in this very weakly basic medium, the Br2+ ion is not completely stable because it undergoes appreciable disproportionation [Eq. (4.198)]. 

BrF6+ Ion. In 1974 Gillespie and Schrobilgen reported the direct oxidation of bromine pentafluoride to BrF6+ cation 339 by Kr2F3+ cation849,850 [Eq. (4.214)]. 

Three very unstable oxides of bromine, BrgQ, BrOg, and BtaO, have been described. The structure of BrgOg is not known. 

The bromine-photosensitized decomposition of O3 was studied at 20° C by Spinks , who used radiation at 5460 and 3650 A. The yield of O3 decomposition was independent of the wavelength or intensity of the radiation and approximately independent of [Br2] and [O3]. Later Mungen and Spinks found the yield to be 30 at 1 °C independent of [O3] and only very slightly dependent on temperature, [Br2], and intensity. Experiments done at higher temperatures (> 20 °C) included water vapor as an inert gas to minimize the thermal reaction. Mungen and Spinks proposed a tentative reaction scheme involving several oxides of bromine as intermediates and wall reactions. However, the results are reasonably well explained by a mechanism analogous to that for the F2-O3 system, viz. 

Derivation From seawater and natural brines by oxidation of bromine salts with chlorine solar evaporation (Great Salt Lake) from salt beds at Stassfurt and the Dead Sea. 

Br" is regenerated in the reaction of oxidation of brominated organic compounds by Ce4+. For example, summation of equations (RIO) + + (R11) + (R1) yields the process... 

No oxides of bromine are known, although three oxacids exist, either in the free state or as salts ... 

Studies on the oxidation of brominated porphyrins revealed the most interesting behavior. A nonlinear trend in the 1/2 for oxidation was first observed by Callot for porphyrins containing 1-4 -pyrrole substituents, and later systematic work on the full series of brominated porphyrins confirmed the initial re-... 

There are only three reasonably well-established oxides of bromine. All three have low thermal stabilities and have not been extensively investigated. Of the oxides of iodine (Table VII), I2O5 is the most stable and useful. 

Thus, all oxides of bromine decompose at or below room temperature, and have no practical importance. We therefore confine ourselves to the more important oxides of chlorine shown in Figure 6.17 and to I2O5 and OF2. 

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