Moura Flávia C C, Araujo Maria H, Dalmázio Ilza, Alves Tânia M A, Santos Leonardo S, Eberlin Marcos N, Augusti Rodinei, Lago Rochel M
Department of Chemistry, Federal University of Minas Gerais, Belo Horizonte, MG 31270-901, Brazil.
Rapid Commun Mass Spectrom. 2006;20(12):1859-63. doi: 10.1002/rcm.2523.
Electrospray ionization (ESI) mass spectrometry (MS) and tandem mass spectrometry (MS/MS) were used to monitor the oxidation of phenol by a novel heterogeneous Fenton system based on a Fe(0)/Fe(3)O(4) composite and H(2)O(2). On-line ESI-MS(/MS) shows that this heterogeneous system promotes prompt oxidation of phenol to hydroquinone, which is subsequently oxidized to quinone, other cyclic poly-hydroxylated intermediates and an acyclic carboxylic acid. A peroxide-type intermediate, probably formed via an electrophilic attack of HOO(.) on the phenol ring, was also intercepted and characterized. ESI-MS(/MS) monitoring of the oxidation of two other model aromatic compounds, benzene and chlorobenzene, indicates the participation of analogous intermediates. These results suggest that oxidation by the heterogeneous system is promoted by highly reactive HO(.) and HOO(.) radicals generated from H(2)O(2) on the surface of the Fe(0)/Fe(3)O(4) composite via a classical Fenton-like mechanism.
采用电喷雾电离（ESI）质谱（MS）和串联质谱（MS/MS）对基于Fe(0)/Fe(3)O(4)复合材料及H(2)O(2)的新型非均相芬顿体系中苯酚的氧化过程进行监测。在线ESI-MS(/MS)结果表明，该非均相体系能促使苯酚迅速氧化为对苯二酚，随后对苯二酚被氧化为醌、其他环状多羟基中间体以及一种无环羧酸。还捕获并鉴定了一种过氧化物型中间体，其可能是通过HOO(.)对苯酚环的亲电进攻形成的。ESI-MS(/MS)对另外两种模型芳香族化合物苯和氯苯氧化过程的监测表明，类似中间体也参与其中。这些结果表明，该非均相体系的氧化作用是通过经典类芬顿机制，由H(2)O(2)在Fe(0)/Fe(3)O(4)复合材料表面产生的高活性HO(.)和HOO(.)自由基所促进的。
