Halogens chemistry

ClOx in the polar boundary layer ClOx by salt flats BrOx in the polar boundary layer BrOx in the Dead sea basin 

Autocatalytic release from sea-salt on ice, Bromine explosion mechanism 

Bromine oxide species can be formed in the polar boundary layer and areas with high salt levels such as the Dead Sea. ° The major source of gas-phase bromine in the lower troposphere is thought to be the release of species such as IBr, ICl, Br2 and BrCl from sea-salt aerosol, following the uptake from the gas phase and subsequent reactions of hypohalous acids (HOX, where X = Br, Cl, 

The halogen release mechanism is autocatalytic and has become known as the Bromine explosion . The Br2 produced in reaction (2.74) is rapidly photolysed, producing bromine atoms that can be oxidised to BrO by O3 (reaction (2.76)) 

With respect to iodine chemistry, the major sources of iodine are thought to be from macroalgal sources releasing organoiodine com- 

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E. Hengge in V. Gutmaim, ed.. Inorganic Silicon Halides in Halogen Chemistry, Vol. 2, Academic Press, Inc., New York, 1967. 

It is not unusual in halogen chemistry to find striking differences in the chemistry of acidic and... 

In an effort to better interpret these results, a literature review on aqueous halogen chemistry was conducted [16,17]. Halogen molecules react in water solution to produce several chemical species as shown in the following equations where X represents Cl, Br, or I. 

Disproportionation, a common process in inorganic halogen chemistry, does not proceed. For example, lOH(HIO) is an unstable, strongly electrophilic compound and, when no substrate is present. 

Jorgensen, C. K. Halogen Chemistry (editor V. Gutmann) 1, 265 (1967). London Academic Press. 

The chemistry involving NOx is closely intertwined with that of the halogens (CIO,. and BrOx) and of HO, so that the predicted effects of a given set of emissions from the HSCT depend on these species as well. Because halogen chemistry is treated in more detail in later sections, we shall focus here primarily on the reasons for the different effects of NO, emissions at different altitudes. How closely these chemistries are intertwined will be apparent in the treatment below of destruction of stratospheric ozone by chlorofluorocar-bons (CFCs) and brominated compounds. 

Crutzen et al. (1992) suggested that the methylper-oxy radical formed in the CH4 oxidation may also play a role in the gas-phase halogen chemistry. (The role of... 

Figure 12.43 summarizes the model-predicted relative importance of these cycles for conditions at 20-km altitude and 43.5°N, assuming total chlorine and bromine levels found in 1990 (Solomon et al., 1996). The importance of the HOx cycles, removal of NOx by the hydrolysis of N205, and the increased importance of halogen chemistry as the particle surface area available for heterogeneous reactions increase, are all illustrated. 

Baum, K., et al. (1978) High Energy Halogen Chemistry. AD A049555. 

Halogen Chemistry, V. Gutman, ed., Academic Press, New York, 1967. 

Kaleschke L, Richter A, Burrows J, Afe O, Heygster G, Notholt J, Rankin AM, Roscoe HK, Holl wedel J, Wagner T, Jacobi H-W (2004) Frost Flowers on Sea Ice as a Source of Sea Salt and Their Influence on Tropospheric Halogen Chemistry. Geophys Res Lett 31 L16114... 

Recently the amino acid sequence of vanadium chloroperoxidase was determined to have similar stretches with three families of acid phosphatases, which were previously considered unrelated [72], This sequence raises questions about the phosphatase activity of apo-V-ClPO and whether the acid phosphatases can coordinate vanadate and carry out peroxidative halogenation chemistry. In fact, apo-V-C1PO does have phosphatase activity, catalyzing the hydrolysis of/i-nitrophe-nol phosphate (p-NPP). In addition, /i-NPP displaces vanadate from V-CIPO. At this point, the haloperoxidase activity of the acid phosphatases containing coordinated vanadium(V) has not been reported. 

Hengge, E. Halogen-Chemistry, Vol. II, p. 169ff. London Academic Press 1967. 

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