Low Cost Transformation of Dioxins to Nontoxic Forms

利用化学还原剂对氯化化合物的光催化还原脱氯，开发了二恶英等氯化化合物向无毒形式的低成本转化。这个过程是通过光诱导电子从催化剂的单重态转移到氯化化合物，然后被氧化的催化剂被化学还原剂还原而开始的。NAD~+类似物(10-甲基吖啶离子)被用作氯代化合物还原脱氯的高效光催化剂。通过电子转移还原和自由基中间体的检测，确定了NAD^+类似物的氧化还原性质。在可见光照射下，对二甲苯的光诱导电子转移到10-甲基-9-苯基吖啶离子的单重态激发态，然后对二甲苯自由基阳离子的去质子化和氧在去质子化自由基上的简单加成，引发对二甲苯高效、选择性地氧化成对甲苯甲醛。阐明了提高光催化剂光催化活性的因素。

The Low cost transformation of chlorinated compounds such as dioxins to nontoxic forms has been developed utilizing photocatalytic reductive dechlorination of chlorinated compounds by chemical reductants. This process is initiated by photoinduced electron transfer from the singlet excited state of the catalyst to chlorinated compounds, which is followed by the reduction of the oxidized catalyst by the chemical reductants. An NAD^+ analogue (10-methylacridinium ion) has been employed as an efficient photocatalyt for the reductive dechlorination of chlorinated compounds. The redox properties of NAD^+ analogues have been determined by examining the electron transfer reduction and the detection of the radical intermediates. The redox properties of the reduced forms, i.e., NADH analogues have also been determined by examining the electron transfer oxidation.The efficient and selective oxygenation of p-xylene to p-tolualdehyde is also initiated by photoinduced electron transfer from p-xylene to the singlet excited state of 10-methyl-9-phenylacridinium ion under visible light irradiation, followed by the deprotonation of p-xylene radical cation and the facile addition of oxygen to the deprotonated radical, leading to yield p-tolualdehyde exclusively as the final oxygenated product. The factors to improve the photocatalytic reactivity of the photocatalyst have been clarified.