Organic phases hydroxylated hydrocarbon phase

A number of significant oxygenated organic particulate compounds and gas-phase free radicals are formed by the reactions of gas-phase hydrocarbons (see Table 6-1 and (Chapter 2). The measurement methods for these substances are complicated and in the research stage. Their description is beyond the scope of this chapter. It is of major importance to develop methods for measuring hydroxyl and peroxyhydroxyl radicals, as well as the various oxygen species formed with ozone (see Chapter 12). 

The majority of PCB photodegradation studies have been carried out in solution with organic or combined solvents preferred due to their low water solubility. Reductive dechlorination is the predominant photodegradation pathway in hydrocarbon solvents as well as alcohols. In aqueous media and alcohols photonucleophi 1 ic displacement reactions yielding phenols or alkoxy derivatives, respectively, also are detected. In the gas phase PCB are photochemically converted to hydroxylated derivatives (26). Photochemical reduction also is the major reaction pathway in thin films (7), solid phase (8) and on silica gel surfaces (9). 

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