ISSN:
1573-0662
Schlagwort(e):
atmospheric aqueous phase
;
biogenicVOC's
;
reactivity
;
free-radicals
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
,
Geologie und Paläontologie
Notizen:
Abstract The reactivity of some selected biogenic monoterpenecompounds towards important aqueous phase free-radicaloxidants, namely OH· and SO4 -·, have beeninvestigated using the complementary experimentaltechniques of pulse radiolysis and laser flashphotolysis (λ = 248 nm). Rate constants forthe reactions of the OH· radical with cis-verbenol andmethacrolein have been determined to be (6.8 ± 0.5) ×109 dm3 mol-1 s-1 and (8.0± 0.7) × 109 dm3 mol-1s-1,respectively (T = 20 °C, pH 4.0, Ionic strength∼ 0 mol dm-3). Rate constants and activationenergies for the reactions of the SO4 -·radical have been measured for the following compounds(T = 20 °C, pH 4.0, Ionic strength = 0.03 moldm-3): α-pinene (k = (3.1 ± 0.1) ×109 dm3 mol-1 s-1;E act. =(8.9 ± 1.3) kJ mol-1), α-terpineol(k = (4.1 ± 0.1) × 109 dm3mol-1s-1; E act. = (13.4 ± 0.6) kJmol-1), cis-verbenol (k = (3.2 ± 0.2) ×109 dm3 mol-1 s-1;E act. =(10.0 ± 0.7) kJ mol-1), verbenone (k = (1.6± 0.1) × 109 dm3 mol-1s-1;E act. = (6.1 ± 0.7) kJ mol-1), myrtenal(k = (1.85 ± 0.1) × 109 dm3mol-1s-1; E act. = (7.5 ± 0.7) kJmol-1)and methacrolein (k = (1.18 ± 0.1) × 109dm3 mol-1 s-1). In most instances theabsorption spectra of the intermediate products formedby these reactions have been measured which, inconjunction with strategic conductiometric studies,have been used to suggest plausible mechanisms for theoxidation in acidic de-oxygenated solution.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1023/A:1006340727148
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