Chlorinated compounds reactions atmosphere

Finlayson-Pitts, B. J., M. J. Ezell, and J. N. Pitts, Jr., Formation of Chemically Active Chlorine Compounds by Reactions of Atmospheric NaCI Particles with Gaseous N205 and CION02, Nature, 337, 241-244 (1989). 

Finlayson-Pitts, B.J., Ezell, M.J., and Pitts, J.N. Jr. (1989) Formation of chemically active chlorine compounds by reaction of atmospheric NaG particles with gaseous N,0, and CIONO, Nature 337, 241-244. 

In 1985, scientists discovered a large decrease in the atmospheric concentration of ozone over Antarctica. This ozone hole could not be explained with the models used to describe atmospheric chemistry at that time, but it has since been explained in terms of an unexpectedly rapid reformation of chlorine atoms from chlorine compounds such as HCl and CIONO2. The new model suggests that reactions such as the following take place on the surface of ice crystals that form in the cold air of the stratosphere over Antarctica. 

The crude acetone produced in the first step of the reaction is first rid of gaseous components (unconverted propylene, propane etc.). The small amounts entrained are absorbed by scrubbing with water at 50°C and atmospheric pressure. The acetone is then distilled to separate the light ends, particularly propionaldehyde, with heavy ends separation to remove the heavy products (water, acetic add, chlorinated compounds such as mono- and dichloroacetones, mono- and dichloropropionaldehydes, etc.). Treatment with caustic soda, carried out in the same final column, facilitates the destruction of the chlorinated compounds and improves the final yield of the operation. 

Nylon 7 and nylon 9 are part of a process developed in Russia to form polyamides for use in fibers. The process starts with telomerization of ethylene. Afree-radical polymerization of ethylene is conducted in the presence of chlorine compounds that act as chain-transferring agents. The reaction is carried out at 120-200 C temperature and400-600 atmospheres pressure. The preferred chain-transferring agents for this reaction are CCI4 and COCh ... 

The di- and monoalkyltin compounds are considered to be effective as stabilizers because they (i) inhibit the onset of the dehydrochlorination reaction by exchanging their anionic groups, X, with the reactive, allylic chlorine atoms in the polymer (ii) react with, and thereby scavenge, the hydrogen chloride that is produced and that would otherwise induce further elimination (jii) produce the compound HX, which may also help to inhibit other undesirable side reactions and iiv) prevent breakdown of the polymer initiated by atmospheric oxidation, i.e., by acting as antioxidants. 

Treatment of triphenylmethyl chloride with silver gave not the expected hydrocarbon but an oxygen-containing compound later found to be the peroxide. The reaction run in an inert atmosphere did give a hydrocarbon, but one with unusual properties. It reacted rapidly with oxygen, chlorine, and bromine, and was quite different from tetra-phenylmethane or what was expected of hexaphenylethane. Gomberg... 

Chemical/Physical. Anticipated products from the reaction of 1,2-dichlorobenzene with ozone or OH radicals in the atmosphere are chlorinated phenols, ring cleavage products, and nitro compounds (Cupitt, 1980). Based on an assumed base-mediated 1% disappearance after 16 d at 85 °C and pH 9.70 (pH 11.26 at 25 °C), the hydrolysis half-life was estimated to be >900 yr (Ellington et al, 1988). 

Chemical/Physical. Anticipated products from the reaction of 1,4-dichlorobenzene with ozone or OH radicals in the atmosphere are chlorinated phenols, ring cleavage products, and nitro compounds (Cupitt, 1980). 

Nitropyrene was the sole product formed from the gas-phase reaction of pyrene with OH radicals in a NOx atmosphere (Arey et al, 1986). Pyrene adsorbed on glass fiber filters reacted rapidly with N2O5 to form 1-nitropyrene. When pyrene was exposed to nitrogen dioxide, no reaction occurred. However, in the presence of nitric acid, nitrated compounds were produced (Yokley et al, 1985). Ozonation of water containing pyrene (10-200 pg/L) yielded short-chain aliphatic compounds as the major products (Corless et al, 1990). A monochlorinated pyrene was the major product formed during the chlorination of pyrene in aqueous solutions. At pH 4, the reported half-lives at chlorine concentrations of 0.6 and 10 mg/L were 8.8 and <0.2 h, respectively (Mori et al, 1991). 

A good white smoke can be obtained by the formation of zinc chloride, ZnCl 2, from a reaction between zinc metal and a chlorinated organic compound (the chlorine-containing species serves as the oxidizer). Reaction products that strongly attract moisture (such as ZnCl 2) will have an enhanced smoke effect in humid atmospheres. The burning of elemental phosphoms, producing... 

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