Phenol chlorination and photochlorination in the presence of chloride ions in homogeneous aqueous solution.
Phenol chlorination and photochlorination in the presence of chloride ions in homogeneous aqueous solution.
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DOI：
10.1021/es0480567
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发表时间：
2005-07
影响因子：
11.4
通讯作者：
D. Vione;V. Maurino;C. Minero;P. Calza;E. Pelizzetti
中科院分区：
文献类型：
--
作者：
D. Vione;V. Maurino;C. Minero;P. Calza;E. Pelizzetti
研究了在辐射下溶解的Fe（III）和氯化物存在下以及在暗酸性溶液中过氧化氢和氯化物存在下苯酚的氯化反应。在前一种情况下，苯酚光氯化最有可能是由于形成Cl 2 *-作为一个后果的Fe（III）照射在氯化物的存在下。最有效的途径是FeOH 2+的光解产生羟基，将氯氧化成Cl*。后者在与氯化物进一步反应后最终产生Cl 2 *-。涉及FeOH 2+的途径的重要性在较高的pH值和适度低的氯化物浓度下更高。在pH 2.0和[Cl-] > 0.03 M时，氯苯酚的生成速率随着[Cl-]的增加而降低，这是由于形成了低得多的光活性物种FeCl 2 +/FeCl 2+。FeCl 2 +/FeCl 2+产生Cl* 的光解可能在pH 0.5和高氯化物下发挥重要作用，但在这种条件下氯苯酚的形成速率比pH 2.0下低约一个数量级。由于pH值和动力学的限制，在大多数环境条件下，与FeOH 2+相比，FeCl 2 +/FeCl 2+的光化学作用可能对氯化作用起次要作用，从而导致羟基介导的氯化物氧化。过氧化氢和氯化物在暗酸性溶液中反应生成HClO，参与亲电氯化过程。在这种条件下氯苯酚的形成速率与[H+]成正比。所描述的氯化和光氯化过程可以发生在海洋来源的酸性气溶胶中，天然富含氯化物和Fe（III）。南极洲的气溶胶也富含过氧化氢，并且由于存在生物来源的硫酸而经常呈强酸性。
Phenol chlorination was studied in the presence of dissolved Fe(III) and chloride under irradiation and of hydrogen peroxide and chloride in dark acidic solutions. In the former case phenol photochlorination is most likely due to the formation of Cl2*- as a consequence of Fe(III) irradiation in the presence of chloride. The most efficient pathway is the photolysis of FeOH2+ producing hydroxyl, which oxidizes chloride to Cl*. The latter finally yields Cl2*- upon further reaction with chloride. The importance of the pathway involving FeOH2+ is higher at higher pH and moderately low chloride concentration. At pH 2.0 and [Cl-] > 0.03 M chlorophenol generation rate decreases with increasing [Cl-], due to the formation of the much less photoactive species FeCl2+/FeCl2+. The photolysis of FeCl2+/ FeCl2+ yielding Cl* is likely to play an important role at pH 0.5 and high chloride, but under such conditions chlorophenol formation rates are about an order of magnitude lower than at pH 2.0. Due to pH and kinetic constraints, under most environmental conditions the photochemistry of FeCl2+/FeCl2+ can be expected to play a minor role toward chlorination when compared with the one of FeOH2+, which leads to hydroxyl-mediated chloride oxidation. Hydrogen peroxide and chloride react in dark acidic solutions to yield HClO, involved in electrophilic chlorination processes. Chlorophenol formation rates under such conditions are directly proportional to [H+]. The described chlorination and photochlorination processes can take place in acidic aerosols of marine origin, naturally rich in chloride and Fe(III). Antarctic aerosol is also rich of hydrogen peroxide and often strongly acidic due to the presence of sulfuric acid of biogenic origin.