Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science & Bioengineering, Beijing University of Technology, Beijing 100124, China.
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China.
J Hazard Mater. 2021 Aug 15;416:125819. doi: 10.1016/j.jhazmat.2021.125819. Epub 2021 Apr 6.
Chloropicrin as one of the most frequently detected N-DBPs has drawn great attention due to its high toxicity. However, our understanding of its formation mechanism is still very limited. A combined computational and experimental approach was used in this study to reveal chloropicrin formation mechanism during chlorination. Ethylamine, n-propylamine, alanine and tryptophan along with the above two amines and their four derivatives substituted by -OH or/and -NO groups were chosen as computational and experimental model precursors, respectively. The results indicate that primary amines and free amino acids are more likely to share the same chloropicrin formation pathway including N-chlorination, imidization, β-C-alcoholization, N-nitration, α-C-chlorination and dealdehydation processes. Moreover, elimination of hydrochloric acid from N,N-dichloro-amine and electrophilic addition of N-chloroalkylimide with hypochlorous acid were found to be the rate-limiting steps among all the elementary reactions. By skipping over both of the above rate-limiting steps, RCH(OH)CHNO and RCH(OH)CHNH(OH) compounds were proposed to be potent chloropicrin precursors, and experiments confirmed that 2-nitroethanol and N-methylhydroxylamine have the highest chloropicrin yields in the chlorination among all the precursors reported to date. The findings of this work are helpful for expanding the knowledge of chloropicrin formation mechanisms and predicting the potential chloropicrin precursors.
三氯硝基甲烷作为最常被检测到的 N-DBPs 之一，由于其高毒性而引起了极大的关注。然而，我们对其形成机制的理解仍然非常有限。在这项研究中，采用了组合计算和实验方法来揭示氯化过程中三氯硝基甲烷的形成机制。乙胺、正丙胺、丙氨酸和色氨酸以及上述两种胺及其四个取代-OH 或/和-NO 基团的衍生物分别被选为计算和实验模型前体。结果表明，伯胺和游离氨基酸更有可能通过相同的三氯硝基甲烷形成途径，包括 N-氯化、亚胺化、β-C-醇化、N-硝化、α-C-氯化和去醛化过程。此外，发现 N,N-二氯-胺中盐酸的消除和次氯酸与 N-氯代亚胺的亲电加成是所有基元反应中的速率限制步骤。通过跳过这两个速率限制步骤，提出 RCH(OH)CHNO 和 RCH(OH)CHNH(OH) 化合物是潜在的三氯硝基甲烷前体，实验证实，在所有迄今为止报道的前体中，2-硝基乙醇和 N-甲基羟胺在氯化中具有最高的三氯硝基甲烷产率。这项工作的发现有助于扩展三氯硝基甲烷形成机制的知识，并预测潜在的三氯硝基甲烷前体。
