Comparison of the Effects of Ultraviolet, H2O2/UV and Gamma-Irradiation Processes on Frozen and Liquid Water Solutions of Monochlorophenols
| Autoři | |
|---|---|
| Rok publikování | 2003 |
| Druh | Článek v odborném periodiku |
| Časopis / Zdroj | Photochemical and Photobiological Sciences |
| Fakulta / Pracoviště MU | |
| Citace | |
| Obor | Organická chemie |
| Klíčová slova | photochemistry |
| Popis | The effects of UV irradiation in the presence or in the absence of hydrogen peroxide as well as of gamma irradiation on 2- and 4-chlorophenol in the solid water ice matrix have been studied and compared to those effects known to occur in aqueous solutions. While UV photolysis (>280 nm) of monochlorophenols provided efficient coupling reactions in ice and photosolvolysis products in liquid water, hydroxylation into chlorobenzenediols is the main pathway in the presence of hydrogen peroxide in both phases. According to the results, the solute molecules accumulate in a layer surrounding the ice crystal walls during the freezing process where they react. Radiation chemistry of chlorophenol ice samples afforded preferably coupling reactions at 78 oC rather than reactions with the OH radicals produced by cleavage of water molecules under given conditions (1 kGy h-1). Apparent resemblance of chemistry in the UV/H2O2 treated liquid, solid, and gamma-irradiated liquid and solid samples is discussed. It is suggested that the reactions of the OH radicals within the polycrystalline ice or snow are important natural processes that should be considered in the environmental, ice-core or astrophysical research. |
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