Availability bromine

Brominated Additive Flame Retardants. Additive flame retardants are those that do not react in the appHcation designated. There are a few compounds that can be used as an additive in one appHcation and as a reactive in another. Tetrabromobisphenol A [79-94-7] (TBBPA) is the most notable example. Tables 5 and 6 Hst the properties of most commercially available bromine-containing additive flame retardants. 

Chemical analysis of the polymer from 2-bromo-4,6-dichloro-phenoxide revealed that somewhere between one half and two thirds of the available bromine was displaced. The presence of residiaal bromine in the polymer is also manifest by the sharp resonance at 118.6 ppm. This residual bromine is also the lilcely cause of the characteristic difference in the 130 ppm region between polymers derived from 2-bromo-4,6-dichloro (2 peaks) and 2,4,6-trichlorophenoxide (3 peaks). In addition to the units 1 and 2, the 2-bromophenoxide could also contain units 3 and 4. ... 

In practice, the required ratio can be different from theoretical, as quite often additional bleach is required to provide HOC1 as an oxidant for algal slimes and other forms of chlorine demand. Also, it is necessary to have a permanent source of oxidant available to effect the promotion of HOBr. However, not all the available bromine generated is lost by biocidal reaction or by (limited) volatility. There is, in fact, some degree of recycling of the bromide ion (Br ) back into HOBr, so monitoring of bromine plus the combined free and total chlorine is necessary to strike the correct halogen balance. 

For bromine to act as a biocide in the most efficient manner, there must always be sufficient free chlorine available in the cooling water to enable HOBr to be formed from all the available bromine compounds (e.g., bromamines). This requires a higher ratio of total chlorine to bromine than normally available with other bromine technologies. 

Although seawater contains only 67 parts per million of bromine in solution, this seemingly rather involved process is both efficient and economical. One cubic mile of seawater contains approximately 300,000 tons of bromine, and the process described permits the recovery of about 80% of the available bromine. 

Besides bromoacetone, other bromomethyl ketones (BrCH2COR) can be used if they are available. Bromination is best carried out with cupric bromide as the reagent, and on ketones in which R contains no a-hydrogens to compete with those on methyl acetophenone, for example, or methyl /er/-butyl ketone. 

Properties Red, prismatic crystals. Mp 135-137C (decomposes) with preliminary softening. The salt is stable in the dry state and can be used in glacial acetic acid, ethanol and related solvents. This compound has 45-50% available bromine. 

Chemical stability of the m-bromo phenol containing epoxy resin was compared with commercially available brominated resins. Epoxy resins were refluxed in N-methyl-pyrrolidinone with 1 N KOH for 15 minutes. Results in Table IV clearly demonstrated the extraordinary chemical stability of the m-bromo-phenol containing epoxy resin over the commercial product. 

This is a chemical Intermediate to a number of active bases, taking advantage of the available bromine atom. This can be exchanged with a sulfur atom (leading to 5-TASB and 3-T-TRIS) or with an oxygen atom as... 

Adding bromide to the reaction mixture would thereby decrease the amount of available bromine and slow down the reaction, but there is no reason why hydrogen ions should affect this equilibrium. Two additional facts were appealed to in order to support Bartlett s two-step mechanism. First, when the reaction is run... 

Kinetic data are available for the nitration of a series of p-alkylphenyl trimethylammonium ions over a range of acidities in sulphuric acid. - The following table shows how p-methyl and p-tert-h xty augment the reactivity of the position ortho to them. Comparison with table 9.1 shows how very much more powerfully both the methyl and the tert-butyl group assist substitution into these strongly deactivated cations than they do at the o-positions in toluene and ferf-butylbenzene. Analysis of these results, and comparison with those for chlorination and bromination, shows that even in these highly deactivated cations, as in the nitration of alkylbenzenes ( 9.1.1), the alkyl groups still release electrons in the inductive order. In view of the comparisons just... 

To a mixture of 0.40 mol of neohexene ( commercially available) and 200 ml of dry diethyl ether 0.35 mol of bromine was added with cooling between -40 and -50°C. The diethyl ether and excess of neohexene were then completely removed by evaporation in a water-pump vacuum.In the second flask was placed a solution of 90 g of commercial KO-tert.-C9H9 (see Chapter IV, Exp. 4, note 2) in 250 ml of DMSO. The dibromo compound was added in five portions during 15 min from the dropping funnel after the addition of each portion the flask was swirled gently in order to effect homogenization. Much heat was evolved and part of the tert.-butylacetylene passed over. After the addition the flask was heated for 30 min in a bath at B0-100°C. 

Acceptors. Most common acceptor molecules such as tetracyanoethylene or tetracyanoqurno dime thane ate commercially available. However, TCNQ can be synthesized in high yield by a two-step synthesis involving a condensation of malonitrile with 1,4-cyclohexanedione followed by treatment with an oxidizing agent such as bromine or A-bromosuccinamide in pyridine solvent (23) (Fig. 6). 

Numerous methods for the deterrnination of monomer purity, including procedures for the deterrnination of saponification equivalent and bromine number, specific gravity, refractive index, and color, are available from manufacturers (68—70). Concentrations of minor components are deterrnined by iodimetry or colorimetry for HQ or MEHQ, by the Kad-Eisher method for water, and by turbidity measurements for trace amounts of polymer. 

DecabromodiphenylOxide. Decabromodiphenyl oxide [1163-19-5] (decabrom) is the largest volume bromiaated flame retardant used solely as an additive. It is prepared by the bromination of diphenyl oxide ia neat bromine usiag AlCl as a catalyst (32). The bromination may also be carried out ia an iaert solvent such as methylene dibromide [74-95-3] (33). The commercially available grades are >98% decabromodiphenyl oxide with the remainder being the nonabromo species. 

Oligomeric Flame Retardants. There are several oligomeric flame retardants. The principal advantage claimed for these materials is their resistance to bloom and plate-out. In some cases they are used at levels high enough that the resulting flame-retarded resia should properly be viewed as a polymer blend or alloy. AH of the available oligomeric flame retardants are brominated (Table 6). 

The Brominated Flame Retardants Industry Panel (BFRIP) was formed ia 1985 within the Flame Retardant Chemicals Association (FRCA) to address such concerns about the use of decabromodiphenyl oxide. Siace 1990 the BFRIP has operated as a Chemical Self-Funded Technical Advocacy and Research (CHEMSTAR) panel within the Chemical Manufacturers Association (CMA) (64). As of 1993, members of BFRIP are Ak2o, Amerihaas (Dead Sea Bromine Group), Ethyl Corp., and Great Lakes Chemical. Siace its formation, BFRIP has presented updates to iadustry on a regular basis (65,66), and has pubhshed a summary of the available toxicity information on four of the largest volume brominated flame retardants (67,68) tetrabromo bisphenol A, pentabromodiphenyl oxide, octabromodiphenyl oxide, and decabromodiphenyl oxide. This information supplements that summarized ia Table 11. 

The halogen fluorides are binary compounds of bromine, chlorine, and iodine with fluorine. Of the eight known compounds, only bromine trifluoride, chlorine trifluoride, and iodine pentafluoride have been of commercial importance. Properties and appHcations have been reviewed (1 7) as have the reactions with organic compounds (8). Reviews covering the methods of preparation, properties, and analytical chemistry of the halogen fluorides are also available (9). 

Bromine Monofluoride. Bromine monofluoride is red to red-brown (4) and is unstable, disproportionating rapidly into bromine and higher fluorides. Therefore, the measurement of its physical properties is difficult and the values reported in Table 1 are only approximate. The uv-absorption spectmm is available (25). 

Bromine Pentafluoride. Bromine pentafluoride is a colorless Hquid having the molecular stmeture of a tetragonal pyramid (5). The index of refraction is 1.3529 (33). Infrared spectra (13,34), the uv-absorption spectmm (35), and vapor pressure data (11) are all available. 

Bromine ttifluoride is commercially available at a minimum purity of 98% (108). Free Br2 is maintained at less than 2%. Other minor impurities are HF and BrF. Free Br2 content estimates are based on color, with material containing less than 0.5% Br2 having a straw color, and ca 2% Br2 an amber-red color. Fluoride content can be obtained by controlled hydrolysis of a sample and standard analysis for fluorine content. Bromine ttifluoride is too high boiling and reactive for gas chromatographic analysis. It is shipped as a Hquid in steel cylinders in quantities of 91 kg or less. The cylinders are fitted with either a valve or plug to faciUtate insertion of a dip tube. Bromine ttifluoride is classified as an oxidizer and poison by DOT. 

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