Details zur Publikation

Referenztyp Zeitschriften
DOI / URL Link
Titel (primär) Analyzing sites of OH radical attack (ring vs. side chain) in oxidation of substituted benzenes via dual stable isotope analysis (δ13C and δ2H)
Autor Zhang, N.; Geronimo, I.; Paneth, P.; Schindelka, J.; Schaefer, T.; Herrmann, H.; Vogt, C.; Richnow, H.H.;
Journal / Serie Science of the Total Environment
Erscheinungsjahr 2016
Department ISOBIO;
Band/Volume 542
Heft Part A
Sprache englisch;
POF III (gesamt) T41;
Keywords Isotope fractionation; OH radical reaction; Aromatic compounds; Competing mechanisms
UFZ Querschnittsthemen RU3;
Abstract OH radicals generated by the photolysis of H2O2 can degrade aromatic contaminants by either attacking the aromatic ring to form phenolic products or oxidizing the substituent. We characterized these competing pathways by analyzing the carbon and hydrogen isotope fractionation (εC and εH) of various substituted benzenes. For benzene and halobenzenes that only undergo ring addition, low values of εC (− 0.7‰ to − 1.0‰) were observed compared with theoretical values (− 7.2‰ to − 8‰), possibly owing to masking effect caused by pre-equilibrium between the substrate and OH radical preceding the rate-limiting step. In contrast, the addition of OH radicals to nitrobenzene ring showed a higher εC (− 3.9‰), probably due to the lower reactivity. Xylene isomers, anisole, aniline, N,N-dimethylaniline, and benzonitrile yielded normal εH values (− 2.8‰ to − 29‰) indicating the occurrence of side-chain reactions, in contrast to the inverse εH (11.7‰ to 30‰) observed for ring addition due to an sp2 to sp3 hybridization change at the reacting carbon. Inverse εH values for toluene (14‰) and ethylbenzene (30‰) were observed despite the formation of side-chain oxidation products, suggesting that ring addition has a larger contribution to isotope fractionation. Dual element isotope slopes (∆ δ2H/∆δ13C) therefore allow identification of significant degradation pathways of aromatic compounds by photochemically induced OH radicals. Issues that should be addressed in future studies include quantitative determination of the contribution of each competing pathway to the observed isotope fractionation and characterization of physical processes preceding the reaction that could affect isotope fractionation.
ID 16927
dauerhafte UFZ-Verlinkung https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=16927
Zhang, N., Geronimo, I., Paneth, P., Schindelka, J., Schaefer, T., Herrmann, H., Vogt, C., Richnow, H.H. (2016):
Analyzing sites of OH radical attack (ring vs. side chain) in oxidation of substituted benzenes via dual stable isotope analysis (δ13C and δ2H)
Sci. Total Environ. 542 (Part A), 484 - 494