Ozone halogen interactions

Oxides of nitrogen play a central role in essentially all facets of atmospheric chemistry. As we have seen, N02 is key to the formation of tropospheric ozone, contributing to acid deposition (some are toxic to humans and plants), and forming other atmospheric oxidants such as the nitrate radical. In addition, in the stratosphere their chemistry and that of halogens interact closely to control the chain length of ozone-destroying reactions. 

The main purpose of this chapter is to survi atmospheric concentrations of photochemical oxidants, with emphasis on surface concentrations and the distribution patterns associated with them. The reason for that em> phasis is that the photochemical oxidants that affect public health and welfare are largely concentrated in this region. The whole subject of stratospheric ozone (and its filtering of ultraviolet light and interactions with supersonic-transport exhaust products), nuclear weapon reaction products, and halogenated hydrocarbon decomposition pr ucts is not treated here. 

The presence of ionizing radiation in the upper regions of the earth s atmosphere and the realization that atmospheric chemistry can occur on the surface of ice and dust particles have lead many authors to study on the interaction of LEE with molecular solids of ozone [203], HCl [236], and halogen-containing organic compounds [176,177,195-197,199-202,205,214,217,224-234] in an effort to shed new light on the problem of ozone depletion. In a recent series of experiments, Lu and Madey [297,298] found that the and CG yields... 

In short, the chemistry of the halogens, NOx, and HOx is intimately connected. As we saw earlier with respect to the HSCT, effects on one of these can affect the other cycles significantly as well, and indeed, the overall effects on stratospheric ozone may be due mainly to these secondary interactions involving other families of compounds. 

Humanes MM, Matoso CM, Da Silva JAL, Frausto da Silva JJR (1995) Volatile Halogenated Compounds of Natural Origin Some Aspects of Their Interaction with Atmospheric Ozone. Qurmica 58 16... 

The BrOA cycle is considered to be more efficient than the CIO A. cycle for ozone destruction because bromine atoms are not removed effectively by hydrogen-atom abstraction reactions12,13. Moreover, the two cycles can interact synergistically with each other to enhance 03 destruction in the lower stratosphere14,15. The importance of reaction 14 is that, in contrast with reactions 8 and 13, it releases halogen atoms without the involvement of atomic oxygen. 

When this work was initiated, there were only a few scattered reports in the literature concerned with the interaction of ozone and halogenated double bonds. The bulk of these reports dealt with the ozonolysis of substrates containing both halogenated and non-halogenated double bonds. In all of these cases the non-halogenated double bond was attacked preferentially by ozone, and only products derived from that kind of reaction were described. 

Chlorine Chemistry in ODEs and Br-Cl Interactions MARINE BOUNDARY LAYER. 4.1 Sea Salt Aerosols Reactive Chlorine Reactive Bromine Reactive Iodine Surface Segregation Effects IMPACT OF HALOGEN CHEMISTRY ON SPECIES OTHER THAN OZONE. 5.1 Alkanes. 5.2 Mercury. 5.3 Sulfur SALT LAKES... 

The cyclopropane chemical reactivity, which closely resembles that of an olefinic double bond, stems from the electronic properties of this three-membered carbocycle Effectively, cyclopropyl and olefinic groups interact with neighbouring 7c-electron systems and p-electron centres they both add acids, halogens and ozone, undergo catalytic hydrogenation and cycloaddition, form metal complexes, etc. 

Section 5.6.3 discussed the chemistries of the halogens chlorine and bromine, and outlined their interactions with one another and with ozone. More than two decades after the pioneering prediction of possible ozone destruction through humankind s use of halogenated chemicals, upper stratospheric ozone observations began to reveal systematic depletion indicative of a changing chemical state (see SPARC, 1998, and references therein). 

Figure 5.28 shows the total ozone loss rate as a function of altitude. Chemical destruction of 03 in the lower stratosphere (< 25 km) is slow. In this region of the stratosphere, 03 has a lifetime of months. Rates exceeding 106 molecules cm-3 s 1 are achieved only > 28 km. Figure 5.29 gives the fractional contributions of the O, NO, HO, and halogen cycles to the total ozone loss rate. In many respects, Figures 5.28 and 5.29 represent the culmination of this chapter—the synthesis of how the various ozone depletion cycles interact at... 

In the paper the interaction of the syndiotactic 1,2-polybutadiene and the reagents of different chemical nature as ozone, peroxy compounds, halogens, carbenes, aromatic amines and maleic anhydride are considered. Various polymer products with a set complex of properties is possible to obtain on the syndiotactic 1,2-polybutadiene basis varying the nature of the modifying agent, a functionalization degree of the polymer and synthesis conditions. 

In the paper the interaction of the syndiotactic 1,2-PB and the reagents of different chemical nature as ozone, peroxy compounds, halogens, car-benes, aromatic amines and maleic anhydride are considered. 

Ozone, in turn, can be destroyed by interaction with another photon that breaks it into an oxygen molecule (O2) and an oxygen atom (O). Stratospheric ozone also can be destroyed by reaction with other species, such as nitric oxide (NO), as shown in Eq. (4.42), and halogen atoms, such as chlorine and bromine. Chlorine and bromine atoms are released into the stratosphere from the photodegradation of haloalkanes, often called halons. Classes of haloalkanes that impact ozone chemistry include CFCs and hydrochlorofluorocarbons (HCFCs). The net concentration of ozone in the stratosphere is established by the rates of both the production and the destruction reactions. 

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