Sodium bromide activation

A derivation of these sodium bromide activation programs is the recent introduction of stabilized liquid bromine, in which the two primary reactants are present in the correct ratio, in one drum, and remain stabilized against reaction until required. 

Sodium bromide is the most rapidly growing antimicrobial ia water treatment appHcations (25). Chlorine dioxide [10049-04-4] has not been historically important, but may have a bright future because of its excellent antimicrobial activity without formation of halomethanes or chloramines (26). 

In 1988, approximately 80% of sodium bromide sales were to the drilling iadustry (10). This usage decreased ia the eady 1990s because of a decrease ia drilling activity and an iacrease ia the use of sodium bromide ia the water treatment iadustry. 

The choice of an ionic liquid was shown to be critical in experiments with [NBuJBr (TBAB, m.p. 110°C) as a catalyst carrier to isolate a cyclometallated complex homogeneous catalyst, tra .s-di(ri-acetato)-bis[o-(di-o-tolylphosphino) benzyl] dipalladium (II) (Scheme 26), which was used for the Heck reaction of styrene with aryl bromides and electron-deficient aryl chlorides. The [NBu4]Br displayed excellent stability for the reaction. The recycling of 1 mol% of palladium in [NBu4]Br after the reaction of bromobenzene with styrene was achieved by distillation of the reactants and products from the solvent and catalyst in vacuo. Sodium bromide, a stoichiometric salt byproduct, was left in the solvent-catalyst system. High catalytic activity was maintained even after the formation of visible palladium black after a fourth run and after the catalyst phase had turned more viscous after the sixth run. The decomposition of the catalyst and the formation of palladium... 

Sodium bromide can be made by passing bromine through an aqueous solution of sodium hydroxide or carbonate in the presence of a reducing agent, such as ammonia, hydrazine, activated charcoal, or Fe2+ ion. A typical method involves adding iron to bromine water to form ferrosoferric bromide, FelFeBrs]. This double salt is dissolved in excess water followed by addition of sodium carbonate. The product mixture is filtered and the filtrate is evaporated to crystallize sodium bromide. The overall reaction may be written as follows ... 

The highest rotation obtained is [a]—820" in aqueous acetone. The active bromides are prepared by dissolving these salts in 50 per cent, acetone, adding small quantities of sodium bromide and diluting- the solution with absolute alcohol. 

Detergents (26, 41, 46, 96, 97) Optimal concentrations of deoxycholate, cholate, Triton X-100, and cetyltri-methylammonium bromide activate, as does urea. Activation of phosphotransferase > that of phosphohydrolase. Supraoptimal levels inhibit, as do all tested concentrations of sodium lauryl sulfate and Tweens 20 and 80. (See also Lysolecithin, Fatty acids, and Long-chain fatty acyl-CoA esters, above)... 

Since those days, various other bromine-based biocides and biocide intermediates have been introduced onto the global market or found renewed favor. The most notable are sodium bromide, isocyanurate/NaBr blends, and DBNPA (a nonoxidizer available as a powder or solution, and recently introduced in tablet form). Most bromine biocides employ chlorine in some form as an activator to produce the primary biocidal species hypobro-mous acid (HOBr). 

Generation of HOBr can be effected by the activation of sodium bromide or (by-product) ammonium bromide, by rapid intimate mixing with chlorine gas or, more usually, sodium hypochlorite. This method is widely used in general industrial cooling systems (as well as other applications, such as brewery pasteurizers, where it provides an alternative to BCDMH chemistry). 

Sometimes, for large cooling systems, an additional static mixer for the bleach is required. In practice, the bleach is often added to the makeup water, or a proportion thereof, at a sufficient dilution to achieve a total halogen level of 1000 to 2000 ppm CI2). There is little point in adding the bleach at any higher concentration, as the limit of activation of sodium bromide is approximately 2500 ppm. Also, the pH of the bleach is very alkaline (typically pH 11 to 12) and sufficient dilution is needed to reduce the pH to permit production of HOBr. 

Simple 2-alkanones, which usually afford optically active alcohols only in low optical yields with modified Raney Ni, have been converted to active alcohols in 72-85% ee by hydrogenation over the Raney Ni modified with optically active tartaric acid and sodium bromide in the presence of an excess amount of pivalic acid (eq. 

Soluble cobalt salts (acetate or naphthenate) are used as catalysts, most often together with manganese and bromide ions. Particularly in the presence of bromide source (as HBr, sodium bromide, or even organic bromides), the rate of the oxidation of methylbenzenes increases by up to 400 x. None of the other halogens approaches bromide in its promoting activity. The maximum effect is achieved with a 1 1 cobaltrbromine atomic ratio. 

Eghbali and Li have recently reported a highly efficient method for the conversion of carbon dioxide to cyclic carbonates in water (Figure 3.14). The organic base l,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was used as a simple carbon dioxide activator at a level of 0.1-0.3 equivalents per mole of alkene. The reaction is catalysed by a catalytic amount of bromine provided by tetra-butylammonium bromide (TBAB) or sodium bromide. During the course of... 

The method used by Lowig and Balard to collect bromine continues to be used today. Chlorine is added to seawater containing sodium bromide or potassium bromide. Chlorine is more active than bromine and replaces bromine in the reaction ... 

In the hydrogenation of p keto esters (R, R) tartaric acid gives the (R) alcohols and the (S, S) tartaric acid gives the (S) enantiomers. Raney nickel is more effective than supported nickel catalysts. It appears that the active catalyst is nickel tartrate which is adsorbed on the catalyst surface and that the sodium bromide is adsorbed on the non-chiral active sites, thus, keeping them from promoting the non-selective hydrogenations. 2,84 -pj is procedure has been used to prepare the chiral intermediate in the synthesis of the Pine Sawfly sex pheromone. ... 

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