International Collaboration in Chemistry: Is the Single Transition State Model appropriate for the Fundamental Reactions of Organic Chemistry?

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。美国国家科学基金会化学部的有机和大分子化学项目支持犹他州立大学弗农·d·帕克教授的一项提议。本论文是与中国南开大学朱晓青教授和程金培教授合作完成的，应NSF 08-602: u.s. Investigators and their同行Abroad （ICC）国际化学合作项目招标提交。本课题组将重点开展一个对机械有机化学具有深远意义的物理有机化学研究项目。这一建议的科学目标是为这个问题提供答案；“单一过渡态模型适用于有机化学中的基本反应吗？”这个问题的基础是，Parker教授提出了一些基本的有机反应的初步证据，包括C-H质子转移反应、氢化物交换反应、碳离子-亲核试剂组合反应、中性-阴离子和中性-中性组合反应、SN2反应以及经典的E2消除反应都是通过两步机制发生的。将两步机制指定为“动力学显著的预关联机制”，以区别于单步机制无法动力学区分的预关联机制。PI的初步非稳态动力学方法，包括“瞬时速率常数分析”，以及他关于单一过渡态模型一般不适用于有机化学基本反应的假设，尚未得到物理有机化学界的普遍接受。开发了一种新的、非常简单的动力学同位素效应（KIE）机制探针，明确区分了一步反应和动力学意义重大的预缔合反应机制。因此，新方法在不需要计算任何速率常数的情况下，对机制进行了区分，并对具有动力学意义的预缔合机制进行了KIE评估。对六种不同的基本反应类型进行了详细的研究。更广泛的影响是巨大的，从学生将在两所大学接受优秀的培训到对物理有机化学领域产生重大影响。总的影响是，这个国际项目将促进美利坚合众国和中华人民共和国科学界之间的合作和善意。该项目将有助于美国国家科学基金会资助培训多样化、全球参与的美国科学工作者队伍。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The Organic and Macromolecular Chemistry Program in the Chemistry Division at the National Science Foundation supports a proposal from Professor Vernon D. Parker of Utah State University. This proposal, submitted in response to solicitation NSF 08-602: International Collaboration in Chemistry between US Investigators and their Counterparts Abroad (ICC), is a collaboration with Professors Xiao-Qing Zhu and Jin-Pei Cheng of Nankai University in China. The research team will focus on a research project in physical organic chemistry with profound importance for mechanistic organic chemistry. The scientific objective of this proposal is to provide an answer to the question; "Is the single-transition state model appropriate for the fundamental reactions in organic chemistry?" The basis for the question is that Professor Parker has presented preliminary evidence that several fundamental organic reactions including C-H proton transfer reactions, hydride exchange reactions, carbenium ion-nucleophile combination reactions, neutral-anion and neutral-neutral combination reactions, SN2 reactions as well as the classical E2 elimination reactions take place by a 2-step mechanism. The 2-step mechanism is designated as the "kinetically significant pre-association mechanism" to distinguish it from pre-association mechanisms which cannot be kinetically differentiated from the single-step mechanism. The PI's preliminary non-steady-state kinetic methods including "instantaneous rate constant analysis" and his hypothesis that the single-transition state model is not generally appropriate for the fundamental reactions of organic chemistry, have not gained general acceptance by the physical organic chemistry community. A new and extremely simple kinetic isotope effect (KIE) mechanism probe has been developed, which unambiguously differentiates between 1-step and the kinetically significant pre-association reaction mechanisms. Thus the new method differentiates between the mechanisms and evaluates KIE for the kinetically significant pre-association mechanism without the need to evaluate any rate constants. Detailed studies of six different fundamental reaction types are proposed. The broader impacts are enormous and range from the outstanding training students will receive at both universities to having a large impact on the field of physical organic chemistry. The overall impact is that this international project will foster cooperation and good will between the scientific communities of the United States of America and the People's Republic of China. This project will contribute to the National Science Foundation's effort to fund training of a diverse, globally-engaged, U.S. science workforce.