Nitrosyl bromide

Nitrosyl bromide (NOBr) decomposes to nitrogen oxide and bromine. Use the following data to determine the order of the decomposition reaction of nitrosyl bromide. 

Formed as an intermediate in the Pb chamber process for sulfuric acid by the reaction of sulfur dioxide, nitrogen trioxide, oxygen and w (chamber crystals) (Refs 1 2). Can be prepd from Ag acid sulfate and nitrosyl bromide (Ref 4)... 

Table 3-1. Equilibrium constants Kxno (Scheme 3-28) and rate constants for diazotization of aniline (Ar2, Scheme 3-29) and of 1-naphthylamine (k2 and k-2/k Scheme 3-34) in water by nitrosyl chloride, nitrosyl bromide, nitrosyl thiocyanate, S-nitrosothiuronium ion [(NH2)2CSNO], and dinitrogen trioxide at 25 °C.

Our latest results in this field stem from a matrix-spectroscopic study of the isomerization of nitrosyl halides (152) and isonitrosyl halides (153).201 Irradiation of nitrosyl bromide (152 X = Br) and nitrosyl chloride (152 X = Cl) leads to the corresponding isomers isonitrosyl bromide (153 X = Br) and isonitrosyl chloride (153 X = Cl). Both compounds, NOBr and NOC1,202 have again been identified by comparison of the experimental and calculated (BLYP/6-311+G ) IR spectra. The back-reactions 153 - 152 can be initiated by UV, visible or IR light. Astonishingly, this retransformation also occurs spontaneously even in the matrix at 10 K under exclusion of any UV/VIS or IR radiation. 

Eisenbrand and Preussman [21] have described a colorimetric technique in which nitrosamines are cleaved to nitrosyl bromide and secondary amines, and the liberated NO+ ion is measured colorimetrically after reacting with N-l-naphthalenyl-1,2-ethanediamine. 

Warburg in the conversion of alanine into the corresponding halogen fatty acid by nitrosyl bromide and in the reconversion of this compound into alanine by the action of ammonia —... 

A change in configuration occurs either by the action of ammonia or by the action of nitrosyl bromide. By studying the conversion by the action of ammonia under various conditions, Fischer was able to show conclusively that this reagent behaved optically normally, which result was confirmed by a later experiment upon optically active trimethyl-a-propiobetaine (a-homobetaine),... 

The change produced by nitrosyl bromide was found to be optically abnormal the following reactions occurred —... 

Silver oxide behaves like nitrosyl bromide, sometimes normally, sometimes abnormally. The changes... 

It may be concluded that the Walden inversion is limited to the reactions between nitrosyl bromide and the amino group and between silver oxide and halogen fatty acid, and is dependent upon the presence of the carboxyl group. 

Bromine reacts with cold nitric oxide forming nitrosyl bromide, NOBr, and nitrosyl tribromide, NOBrs. 

Reactions with chlorine and bromine form nitrosyl chloride and nitrosyl bromide, respectively ... 

Another method of preparation involves the reaction of nitrosyl bromide with silver bisulfate ... 

Nitrosyl bromide also added to imines but the yields of a-acetates after the addition of silver acetate were not better than these obtained by the addition of nitrosyl chloride. Because of their high reactivity, it was not possible to isolate a-bromodialkylnitrosamines in either case. Presumably, steric effects may also operate. 

Both gaseous products, nitrosyl chloride and nitrosyl bromide, absorb light strongly in the visible (Chapter 4) and hence photolyze readily at dawn, producing atomic chlorine and bromine, respectively. 

In a study of the addition of nitrosyl chloride or nitrosyl bromide to norbor-nene and norbomadiene, it was observed that (a) there was no structural rearrangement during the reaction, (b) a cis addition had taken place, (c) nucleophilic solvents such as ethanol or acetic acid were not incorporated in the products. These facts seem to speak against an ionic addition mechanism, while a free radical initiated by NO radicals was considered unlikely since nitric oxide is inactive toward norbomadiene. Therefore a four-center mechanism has been suggested [70], However, when a relatively simple, unstrained olefin such as A9-octalin was subjected to the reaction, only blue, crystalline, monomeric 9-nitroso-10-chlorodecalin was produced. This product had a trans configuration. Thus it is evident that the structure of the olefin has a significant bearing on the steric course of the addition [71]. 

The following two preparations illustrate the addition of nitrosyl halides to norbornene. In the first one, nitrosyl chloride itself is used in the second, nitrosyl bromide is generated in situ. 

On the other hand, nitrosyl bromide is ineffective. This may be attributed to the fact that the reagent is extensively dissociated to afford nitric oxide and molecular bromine. Furthermore, in the case of some amides, reaction with nitrosyl bromide results in the formation of complex crystalline compounds containing reactive bromine. 

The reaction of nitric oxide with bromine to form nitrosyl bromide has not been so thoroughly investigated. 

Nitrosyl bromide, NOBr, mw 109.92 brn gas or dk-brn liq, fr p 55.5°, bp -2°C formed by passing NO into bromine at -15°(at RT NOBr3 is formedXRef 1). According to Sax(Ref 4)> this compd is severely toxic since single exposure can cause injury or mucous membrane sufficiently serious to threaten life or cause physical impairment... 

The gas-phase reaction of nitric oxide and bromine yields nitrosyl bromide ... 

According to H. H. Landolt, if nitrosyl bromide be gradually heated to about 30°, the residue which remains contains from 82-64 to 83-64 per cent, of bromine. This corresponds with nitrosyl dibromide, N202Br4, or NOBr2. He called it Bromunter-salpetersdwe. The product is very dark brown, and resembles bromine it begins... 

Rate coefficients (k, eqn 16) and activation energies for nitrosation by nitrosyl bromide in aqueous solution... 

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