摘要
本研究采用量子化学计算研究了羟基自由基引发的磺胺甲恶唑加成反应与抽氢反应的机理,系统考察了水相中的反应动力学,应用ECOSAR软件预测并评估了加成产物的生态毒性.研究结果表明,磺胺甲恶唑的C_(8)、C_(12)及C_(16)等位点的平均局部离子化能较低,说明它们更易与羟基自由基发生反应.除C17和H21外,其他位点的反应过程均放热,并且C1位点的加成反应与C—S键的裂解存在协同效应;加成反应和抽氢反应的活化自由能在4.0—28.6 kcal·mol^(−1)之间变化,最小值和最大值分别发生在C_(8)和H9位点;虽然反应的速率常数达到4.97×10^(12) L·mol^(−1)·s^(−1),但因受扩散控制使其在水相中的表观反应速率常数仅为8.68×10^(9) L·mol^(−1)·s^(−1).毒性预测结果显示,尽管大部分加成产物的生态毒性较母体化合物低,但C_(8)、C_(12)和C_(16)位点上的加成产物仍具有较高的生态毒性风险.
The mechanisms of sulfamethoxazole addition and abstraction reactions initiated by hydroxyl radicals were investigated based on quantum chemistry calculation.Meanwhile,their reaction kinetics in aqueous phase were explored in details.Furthermore,the eco-toxicity of the addition products was predicted and assessed by using ECOSAR software.The results showed that the C_(8),C_(12) and C_(16) sites of sulfamethoxazole had low average local ionization energies,indicating their higher reactivity with hydroxyl radicals.With the exception of C17 and H21 sites,the reactions occurring at other sites were exothermal and the addition reaction at C1 site was synergic to C-S bond cleavage.The activated free energies of reactions varied in the range of 4.0—28.6 kcal·mol^(−1) and the maximum and minimum values belonged to C_(8) and H9 sites,respectively.Although the total rate constant of second-order reaction for the addition and abstraction reactions was 4.97×10^(12) L·mol^(−1)·s^(−1),the apparent rate constant was only 8.68×10^(9) L·mol^(−1)·s^(−1) in that the reactions were controlled by diffusion in aqueous phase.Further results of toxicity prediction indicated that most adducts had lower eco-toxicity than the parent compound.However,the adducts formed at the sites of C_(8),C_(12) and C_(16) still had high eco-toxicity risks to aqueous organisms.
作者
郑丽英
杨基峰
欧利辉
靳俊玲
李静雅
李超群
罗胜联
ZHENG Liying;YANG Jifeng;OU Lihui;JIN Junling;LI Jingya;LI Chaoqun;LUO Shenglian(Hunan Province Engineering Research Center of Electroplating Wastewater Reuse Technology,Hunan Provincial Key Laboratory of Water Treatment Functional Materials,College of Chemistry and Material Engineering,Hunan University of Arts and Science,Changde,415000,China;College of Environmental and Chemical Engineering,Nanchang Hangkong University,Nanchang,330063,China)
出处
《环境化学》
CAS
CSCD
北大核心
2022年第12期3965-3972,共8页
Environmental Chemistry
基金
国家自然科学基金(51938007,52170033)
湖南省自然科学基金(2020JJ4450)资助.
