Cyanogen bromide vapor

The interaction of cyanogen bromide vapors with solid o-hydroxyaniline (236u) or the solid benzhydrazides 324 at room temperature provides the 2-aminobenzoxazole (433) or the 2-amino-5-aryl-aminooxadiazole salts 434 [92] (Scheme 68). These 3-cascades imply formation of the cyanamide, its cyclization, and tautomerization. 

Cyanogen bromide. Dissolve 20g cyanogen bromide in 800ml H2O. Add 200 ml 95% ethanol. Mix and add 0.5 ml Brij-35 and store in a glass bottle. Caution - cyanogen bromide vapors are toxic prepare reagent in well-ventilated hood ... 

Brom-benzol, n. bromobenzene. calcium, n. calcium bromide, -cyan, n. cyanogen bromide, bromocyanogen. -dampf, tn. bromine vapor, -eisen, n. iron bromide, -fiasche, /. bromine bottle, -fluor, n. bromine fluoride, -gehalt, tn. bromine content, -gold, n. gold bromide, -goldkalium, n. potassium auri-bromide, potassium bromoaurate. bromhaltig, a. contaim ng bromine, Brom-hydrat, n. hydrobromide bromine hydrate. -hydrin, n. bromohydrin. 

Cyanogen bromide is a solid with a high vapor pressure at room temperature therefore, it is recommended to use a commercially available solution of BrCN in acetonitrile. 

Konig A 2% p-aminobenzoic acid in ethanolic hydrochloric acid (0.6 M) is sprayed on the plate that has been exposed (1 h) to vapors of cyanogen bromide. 

Baxter, G.P., Bezzenberger, F.K., Wilson, C.H. (1920) The vapor pressures of certain substances Chloropicrin, cyanogen bromide, methyl-dichloro-arsine, phenyl-dichloro-arsine, diphenyl-chloro-arsine and arsenic trichloride. J. Am. Chem. Soc. 42, 1386-1393. 

Caution Prepare this solution in a hood, as cyanogen bromide volatilizes at room temperature, and the vapor is highly irritating and poisonous. 

Hazards Handle 99% anhydrous hydrazine with care. Never distill it in the presence of air, and keep it out of contact with strong oxidizers. Wear gloves, and use proper ventilation when handling cyanogen bromide. Cyanogen bromide is highly poisonous, and inhalation of vapors, or skin absorption can be fatal toxic effects are similar to hydrogen cyanide. 

The bromination of poly-DCH is of interest because the degree of bromine uptake can be controlled, by choice of experimental conditions, between 3 and 8 Br atoms per polymer repeat unit and because a crystal-to-crystal transformation is observed. Scheme 1 summarizes the reactions of liquid bromine with poly-DCH. Interaction of poly-DCH crystals with dense vapors of bromine or cyanogen bromide for months did not lead to detectable weight gain. By contrast, DCH monomer (2a), which has a crystal structure similar to the polymer (6), readily reacts with bromine vapor to give an eunor-phous material which has gainbd ca 12 Br atoms per molecule. 

Iodine vapor allows nonspecific, usually nondestructive detection of many sub-stances (e.g. surface active agents [129], pharmaceuticals [130, 131], polyethylene glycols [132], see also Table 12). In addition, reactions have also been described with the vapors of bromine [133—135], cyanogen bromide [136], chlorine [137-141, 209], ammonia [147-147] (see also the reagent Ammonia vapor ). 

Caution. Cyanogen bromide (BrCN) (5 M acetonitrile solution or solid) is corrosive, volatile (fumes in air), and toxic. Use safety gloves and goggles, avoid inhalations of vapors, and conduct all operations in a well-ventilated hood far from ignition sources. 

Detection. Automatic detectors are available which detect attack concentrations of vapors of hydrogen cyanide, cyanogen chloride and cyanogen bromide. Draeger tubes are also available, as are water testing kits. 

Needles, cubes volatile at Ordinary temps. Vapors are highly irritant and very poisonous df 2.015. mp 52. bp 61 >62. Freely sol in water, alcohol, ether. Aqueous solns of alkalies dec it to alkali cyanide and alkali bromide. Pure cyanogen bromide, completely dried by distillation over sodium, may be stored in a desiccator for several months. Impure material dec rapidly and tends to explode. 

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