多氯代有机化合物的氯同位素是完全二项分布的吗？理论研究与实验启示
Are Chlorine Isotopologues of Polychlorinated Organic Compounds Exactly Binomially Distributed? A Theoretical Study and Implications to Experiments
摘要：
多氯有机化合物的氯同位素通常被认为遵循二项分布。这种认识是正确的吗？本研究提供了一个坚实的理论推导，以证明有机氯的同位素分布是否是二项或不，并探讨了相关的实验研究的分布的含义。在合成反应中，较强的C-Cl键更容易与重同位素形成。强C-Cl键断裂时的氯KIE值高于弱C-Cl键断裂时的氯KIE值。对于合成有机氯，如果氯化反应的限速步骤是C-Cl键的形成，则氯KIE在反应中起作用，导致反应位置上的氯同位素比总是高于来自氯源的初始氯原子的氯同位素比。不同的氯化反应过程中氯的KIE值不同，导致不对称反应中间体和最终产物的不同反应位置上的氯同位素比值不一致。如果速率控制步骤是反应性氯原子的产生，并且氯源的初始同位素比是恒定的，则所有中间体和最终产物的反应位置上的氯同位素比是相等的，表明同位素体遵循二项分布。经过物理变化和脱氯反应后，环境中的有机氯不太可能呈二项式分布。实验数据表明，所研究的有机氯化合物的同位素体均不服从二项分布。本研究为有机氯的氯同位素分布研究提供了新的视角，为有机氯的定量分析和CSIA-Cl提供了更好的数据。
英文摘要：
Chlorine isotopologues of polychlorinated organic compounds are usually recognized to follow binomial distribution. Is this recognition exactly true? This study presents a solid theoretical derivation to prove whether the isotopologue distributions of organochlorines are binomial or not, and investigates the implications of the distributions to relevant experimental studies. During synthetic reactions, the C-Cl bonds with stronger strengths are more readily to be formed with heavy isotopes. The chlorine KIEs are higher during the breakages of the stronger C-Cl bonds than during the breaking of the weaker ones. For a synthetic organochlorine, if the rate-limiting step during a chlorination reaction is the formation of C-Cl bonds, then chlorine KIE takes effect in the reaction, resulting in always higher chlorine isotope ratio on the reaction position than that of the initial chlorine atoms from the chlorine source. Chlorine KIEs vary during different chlorination reactions, leading to inconsistent chlorine isotope ratios on different reaction positions of asymmetric reaction intermediates and final products. If the rate-determining step is the generation of reactive chlorine atoms and the initial isotope ratio of the chlorine source is constant, then the chlorine isotope ratios on the reaction positions of all intermediates and final products are equivalent, demonstrating that the isotopologues follow binomial distribution. After physical changes and dechlorination reactions, organochlorines in the environment are unlikely binomially distributed. Experimental data show that the detected isotopologues of all the investigated organochlorines disobeyed binomial distribution. This study may bring a new perspective about the chlorine isotopologue distributions of organochlorines, and the proposed solutions may help to obtain better data for quantification and CSIA-Cl of organochlorines.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
