Bromine benzene

Arrange the following five compounds in order of decreasing rate of bromination benzene toluene o xylene m xylene 13 5 tnmethylbenzene (the relative rates are 2 X 10 5 X 10" 5 X 10 60 and 1)... 

Potential hepatotoxic effects of various brominated benzenes, however, should be considered. Bromobenzene which is a monobrominated compound, is used in various experiments as a model hepatotoxic compound (refs. 9-11). 

In addition, data on the accumulation of several brominated benzenes by juvenile Atlantic salmon are presented, and the accumulation of brominated benzenes is correlated with the measured transport rates. 

Consequently, with the possible exception of pentabromoben-zene, hexabromobenzene may be the only brominated benzene which does not accumulate in fish. 

Kuramochi, H., Maeda, K., Kawamoto, K. (2004) Measurements of water solubilities and 1-octanol/water partition coefficients and estimations of Henry s law constants for brominated benzenes. J. Chem. Eng. Data 49, 720-724. 

EPA. 1986i. Testing and reporting requirements for polyhalogenated dibenzo-p-dioxins/dibenzofurans Addition of chlorinated and brominated benzenes to list of precursor chemicals. U.S. Environmental Protection Agency. Federal Register 51 37612-37613. 

Only minor catalytic activity of CuCl2 in oxychlorination of arenes is, however, observed in the liquid phase at 80 °C251. Aqueous HBr brominates benzene at 325 °C in presence of air and Fe/silica-alumina catalyst252. 

In a paper recently published 2>, we point out that, except for a bromine-benzene complex studied by Duchesne, the results reported in the literature do not offer any clear evidence for charge transfer. A systematic observation of both nitrogen and chlorine resonances in some complexes led us to admit the existence of a small transfer (0.05 electron) in chloroform complexes with amines and pyridine derivatives. Though the number of compounds studied is still small, the observed effects are not thought to be due to mere coincidence, and it appears very desirable to extend such experiments especially for stronger complexes. 

The uptake of some brominated benzenes and polybrominated biphenyls in fish (Atlantic salmon) was investigated in 1976 for the first time in a static test by Zitko and Hutzinger [250]. After 96 hours, they found no uptake of hexabro-mobenzene (HBB) from water or food in Salmo salar. The fish contained 2.3% hexane-extractable fat. The polybrominated biphenyls were accumulated to a lower extent than the polychlorinated biphenyls. Zitko and Hutzinger [250] suggested that HBB with a high molecular weight of 552 can not be taken up by fish. They concluded also that it is possible that HBB can be taken up by fish but that this compound may be converted into a non-extractable form in fish. Experiments with C-labeled HBB are required to determine its fate. But as far as we know, no bio concentration experiments with C-labeled HBB and fish were conducted. 

Benzene and Bromine.— Benzene, however, does not act in this way with bromine nor at all with hydrobromic acid. When bromine acts on benzene the product usually formed is a substitution product,... 

One of the simplest ways to brominate benzenes is not to bother with the Lewis acid catalysts recommended in Chapter 22 but just to add liquid bromine to the aromatic compound in the presence of a small amount of pyridine. 

For quality control reasons, rapid screening methods are needed to identify the volatiles in polymeric materials collected for recycling. HS-SPME-GC-MS was shown to be a fast and sensitive method to screen for brominated flame retardants in recycled polyamide materials [78]. HS-SPME effectively extracted several brominated compounds, all possible degradation products from the common flame-retardant Tetrabromobisphenol A from recycled polyamide 6.6. Furthermore, the high extraction capacity of the PDMS/DVB stationary phase towards aromatic compounds was demonstrated, as the HS-SPME-GC-MS method allowed the extraction and iden-tiflcation of brominated benzenes, from a complex matrix only containing trace amounts of analytes. In addition, degradation products from an antioxidant, a hindered phenol, were extracted. Figure 14 shows a typical chro-... 

Chlorinated and brominated materials are burned or thermally treated in a variety of combustion sources including hazardous and municipal waste incinerators, industrial processes, backyard trash burning, and accidental fires. Chlorinated materials are used in a wide range of applications and brominated compounds are fire retardants used in many devices including electronic circuits. Although there has been some research on the reactions of CHCs and BHCs in the past 20 years, too little is known about their reactions considering the magnitude of the environmental impact. Elementary reaction studies of gas-phase reactions of Cj and C2, CHCs, and BHCs are needed to understand their most fundamental reaction properties. Reactions of the chlorinated and brominated benzenes and phenols are important intermediate steps in the formation of PCDD/F. Recent kinetic models indicate that the gas-phase reactions may be quite important and elementary gas-phase reaction studies have been overlooked by researchers. 

Mellitic Acid, C6(COOH)6, is of interest as it contains six carboxyl groups. It occurs in peat as the aluminium salt, which is called honey-stone, C6(C00)6Al2.18H20. The acid is formed as the result of the oxidation of lignite, wood-charcoal, or graphite with potassium permanganate. It crystallizes in silky needles, and is not affected when treated with nitric acid, sulphuric acid, or bromine. Benzene is formed when the calcium salt of mellitic acid is heated with lime. 

If we brominated benzene in the presence of methanol, we should expect the formation of anisole (C6H5OCH3) instead of bromobenzene. 

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