Bromine release agents

Further subjects in the spotlight are foaming agents, notably CFCs, which are now forbidden in many countries. Other additives or processing aids under debate, such as brominated and other halogenated flame retardants, cadmium and lead heat stabilisers and release agents which cause damage to the ozone layer, are discussed in more detail in Table 3.5 of Chapter 3. 

Sodium bromide is occasionally employed as an algicide. Typically 3.5 ppm of sodium bromide added. The bromide is converted to hypobromous acid by the subsequent addition of a fast dissolving chlorine biocide sufficient to achieve 10 ppm FAC. This temporarily converts the pool to a bromine system. The pool is reconverted to chlorine by subsequent high doses of chlorine release agents. 

Figure 4 Stabilized bromine antimicrobials are produced by eosinophils, a type of mammalian white blood cell. Bacteria are captured by phagocytosis and contained intracellularly within vesicles called phagosomes. Granules release cationic surfactants, lytic enzymes, and eosinophil peroxidase into the phagosome in a process known as degranulation. Eosinophil peroxidase, an enzyme that is structurally similar to the bromoperoxidases found in seaweed (Figure I), selectively catalyzes oxidation of bromide to hypobromite by reducing hydrogen peroxide to water. The hypobromite immediately reacts with nitrogenous stabilizers such as aminoethanesulfonic acid (taurine) to form more effective and less toxic antimicrobial agents.

No specific biologic marker/test is available for pulmonary agents as a class however, exposure to bromine might be indicated by detection of elevated bromide levels in serum (reference level is 50-100 mg/L), or if chlorine or bromine is released and they are detected in environmental samples. The case can be confirmed if laboratory testing is not performed because either a predominant amount of clinical and nonspecific laboratory evidence is present or an absolute certainty of the etiology of the agent is known. 

Reduction of triarylbismuth dihalides to the parent triarylbismuthines can be performed by using a variety of reducing agents, which include hydrazine hydrate, sodium hydrosulfite, liquid ammonia, LiAlH4, NaBH4, sodium sulfide and sodium dialkyldithiocarbamate. This type of reduction has been used for the purification of tris(3-methylphenyl)bismuthine which is purified with difficulty in the trivalent state [26JA507]. The electrolytic reduction of triphenyl-bismuth dibromide has been found to be a one-step, two-electron process where the bromine atoms are released as bromide ions [66JA467]. 

CALCIUM PHOSPHIDE (1305-99-3) CajPj A strong reducing agent. Forms highly toxic and flammable phosphine gas in moist air may spontaneously combust. Violent reaction with oxidizers, hydrochloric acid bromine, chlorine, chlorine monoxide, dichlorine oxide, fluorine, oxygen, sulfur. Violent reaction with water, steam, acids, alcohols, releasing phosphine gas and phosphine dimer, with risk of fire and/or explosion. Elevated temperatures form thick smoke and phosphoric acid. Attacks some metals and coatings. On small fires. Do not use water or foam. 

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