In acidic (pH ≈ 1,3-1,9) and alkaline (pH ≈ 11) aqueous solutions the reaction kinetics of the OH' radical induced o. Jalion of phenol, o-, m- and pcresol were studied by pulse radiolysis. The formation nineties of phenoxyl and melhylphenoxyl radicals, resp., are described by two, consecutive reaction steps: the first is addition of OH'radicals to llm aromatic ring, while the second H2O or OH elimination. The rate constants of the addition of OH'radicals are the same, (1,4) 1010 mol-1 dm3 s'1 for phenol and the three cresi isomers: this relates to diffusion controlled process. The rate constant of the adddition is nearly indej undent of the pH. The phenoxyl '.ad mcthylphenoxyl radicals are produced from the adducts in acidic solutions (pH = 1,3-1,9) by H2O elmination with a rate constant of (1,6±0,2) · 106s-1 but in alkaline systems (pH ≈ 11) by OH~ eliminnlioi with considerably faster reaction, (9-12) -10 s-1. The rate constants of production of methylphenoxyl radicals from cresol isomers are practically the same as that of phenoxyl from phenol: it means that the methyl substitution and the position of it influences neither the vulc of the OH-addition nor that of the H2O/OH- eliniation.
|Number of pages||5|
|Journal||Magyar Kemiai Folyoirat, Kemiai Kozlemenyek|
|Publication status||Published - Dec 1 1998|
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