KMnO4氧化降解阻燃剂四氯双酚A的动力学、氧化产物及反应路径

为探讨KMnO4氧化降解阻燃剂四氯双酚A(TCBPA)的动力学、氧化产物及反应路径, 在不同pH条件下, 研究KMnO4氧化降解TCBPA的动力学规律, 利用三重四级杆液相质谱联用仪(LC-MS/MS)对KMnO4降解TCBPA的氧化产物进行检测分析, 并推测反应路径.结果表明, KMnO4氧化降解TCBPA的二级反应速率常数k(40.1~981.7 L/(mol·s))随着pH的升高先增加而后降低, 在接近pKa(7.5/8.5)时最大.子找母质谱扫描方法(LC-MS/MS-PIS)测得KMnO4氧化降解TCBPA产生4个主要产物, 质量数(m/z 35)分别为219/221(Ⅰ)、201/203(Ⅱ)、379/381/383/385(Ⅲ&Ⅲ′)、523/525/527/529/531/533(Ⅳ).KMnO4氧化降解TCBPA的反应路径为TCBPA首先发生一电子反应形成酚氧自由基, 并进一步断裂形成碳正离子中间体, 然后反应形成产物4-(2-羟基异丙基)-2, 6-二氯苯酚(Ⅰ)、4-异丙烯-2, 6-二氯苯酚(Ⅱ)和两个聚合产物(Ⅲ&Ⅲ′和Ⅳ).
The purpose of this article was to investigate the kinetics, oxidation products and reaction pathways for the degradation of flame retardant tetrachlorobisphenol A (TCBPA) by aqueous potassium permanganate. Experiments were conducted to examine the reaction kinetics of potassium permanganate with TCBPA under the condition with potassium permanganate in excess over a wide pH range, determine the brominated oxidation products and theorize the reaction pathways of TCBPA by aqueous potassium permanganate using liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS). The results showed that the degradation of TCBPA followed the second-order kinetics and the rate constants (40.1-981.7 L/(mol·s)) increased with the increase of pH and reached the maximum near the pKa (7.5/8.5) of TCBPA, after which they decreased gradually. Four chlorinated oxidation products were detected by the precursor scan approach of liquid chromatography tandem mass spectrometry (LC-MS/MS-PIS), the oxidation products of m/z 219/221(Ⅰ), 201/203(Ⅱ), 379/381/383/385(Ⅲ&Ⅲ′), 523/525/527/529/531/533(Ⅳ), respectively. Reaction pathways mainly involves the initial one-electron oxidation of TCBPA to phenolic radical and subsequent release and further reactions of 2, 6-dibromo-4-isopropylphenol carbocation intermediate, leading to the formation of 4-(2-hydroxyisopropyl)-2, 6-dibromophenol and 4-isopropylene-2, 6-dibromophenol) as well as two polymeric products(Ⅲ&Ⅲ′and Ⅳ).