Bromine history

On September 6, 1987, the European Economic Community and the United States signed a phase-out agreement for the manufacture and use of specific refrigerants containing chlorine and bromine in the hydrocarbon molecule because of the effects on the atmosphere s ozone layer. ° See Reference 20, p. 18.1, for a more detailed history of this... 

Bromine.—Of the three halogens, chlorine, bromine, and iodine, bromine has the least eventful history. Its elemental nature and its relation to chlorine and iodine were recognized from the very first. While studying the mother-liquid which remains after the crystallization of salt from the water of the salt-marshes of Montpellier, A. J. Balard was attracted by the intense yellow coloration developed when chlorine water is added to the liquid. A. J. Balard digested the yellow liquid with ether decanted off the supernatant ethereal soln. and treated this with potassium hydroxide. The colour was destroyed. The residue resembled potassium chloride but unlike the chloride, when heated with manganese dioxide and sulphuric acid it furnished red fumes which condensed to a dark brown liquid with an unpleasant smell. 

The history of the bromides dates from the discovery of bromine by A. J. Balard1 in 1824. He prepared potassium bromide by the action of bromine on potash lye, and calcined the residue remaining on evaporating the product to dryness. The bromine in sea-water may be present as alkali bromide, but more probably as magnesium bromide. It is, however, uncertain how the bromides are distributed and similar remarks apply to the bromides present in spring and mine waters. Potassium bromide is used in chemical laboratories medicinally in some nervous diseases and in photography. 

Stratospheric Ozone depletion is largely due to chlorine and bromine radicals released from halogenated hydrocarbons. This paper describes properties, emission histories and budgets of relevant substances and outlines the pertinent photochemical processes, along with a comprehensive presentation of halocarbon measurements and global distributions. 

As yet, little is available in terms of properly documented iodine treatment case histories, but it is difficult to see the advantages of iodine chemistry over bromine chemistry for most general-purpose cooling systems. 

The RoHS procedure has now combined with European Union Registration, Evaluation, Authorisation and restriction of Chemicals (REACH), which is a new European Union Regulation (EC/2006/1907 of 18 December 2006). Four additional substances are listed that will be assessed as a priority, among these substances is hexabromocyclododecane, a brominated flame retardant widely used in expanded polystyrene for which no alternatives have been found so far. REACH addresses the production and use of chemical substances and their potential impacts on both human health and the environment it has been described as the most complex legislation in the Union s history and the most important in the last 20 years. It is the strictest law to date regulating chemical substances and will impact industries throughout the world. REACH entered into force in June 2007, with a phased implementation over the next decade. 

BOL-148 is of special interest because it played a considerable role in psychedelic history. BOL-148 differs from LSD-25 by a single bromine atom, which renders it inactive in terms of mental function. Yet it is capable of producing more anti-serotonin activity than LSD, and it also produces some cross-tolerance with LSD. This compound seems to contradict the simple model that the effects of psychedelics are mediated by serotonin. 

However, we should keep in mind that in spite of a long history of testing we have been unable to foresee the environmental hazards of many anthropogenic substances, such as DDT, PCB, chlorinated paraffins, brominated flame retardants, PFOS and lately the pharmaceutical drug diclophenac (Oaks et al. 2004). Mankind and the environment pay a high price for these mistakes and we have to do a better job in the future. So the new challenge is When we replace one test method with a new one, it should not just be as good but better than what we have used before. 

Brominations are, in most cases, carried out by methods similar to those for the preparation of chlorine derivatives. Sampey (127) gives a history of the photobromination of benzene and toluene. Davis (123) made a thorough examination of the relative rates of bromination of the olefins, concentrating particularly on ethylene. An unusual method for producing bromine compounds is by the use of bromosuccinimide or related compounds. This method is called the Wohl-Ziegler reaction and causes allylic bromination. It has been the subject of a couple of reviews (124,1 0). 

A flame retarded rigid PU foam needs around 20-25% chlorine or 5-6% bromine or 1.5-2% phosphorus [1, 2, 4, 11]. During the history of PU many reactive flame retardants were developed, but only a few are used effectively in practice. 

It has been found that only the bromine F centers contribute to the photostimu-lability, although the X-ray irradiation creates both fluorine and bromine F centres [18]. These authors have also derived estimates of the concentrations of defect centers in a particular BaFBr Eu- sample. Even if these values arc not very reliable, they illustrate how complicated the physical mechanisms in a storage phosphor may be 82% of the centers created by irradiation are fluorine F centers or variants therebf these do not contribute to the photostimulable luminescence. The remaining 18% of the created centers are bromine F centers. Of these about one quarter arc spatially correlated to the hole center and the Eu ion, i.e. they yield PSL via a tunelling mechanism the others are not correlated and need thermal activation via the conduction band in order to yield PSL. These estimated concentrations depend strongly on the history of the sample and on the Eu concentration. 

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