Ab Initio Calculations on Proton Transfers

9313657 Saunders质子从酸中转移，其中电离质子是 将通过量子化学的方法来研究 方法.能量和其他性质的分离 反应物、离子偶极络合物和跃迁 质子转移的状态结构将被计算为 一些碳酸，产生离域阴离子， 有机合成中广泛使用的那种。一项研究还将 是由含氧酸的原型制成的， 离域阴离子，乙醛烯醇，和比较将 会变成碳中心酸乙醛目的 这项研究的目的是探索 影响质子转移势垒：酸度、重原子 重组、电荷转移和极化。这些 气相计算将与文献进行比较 实验结果在气相和溶液。 同位素效应的计算将在选定的 系统，包括通过氢氧离子使丙烯去质子化 和消除反应来确定 为了给出合理的同位素， 效果，并与实验数据进行比较 在溶液中。 %有机动力学计划的这一赠款支持 威廉·H教授的工作。桑德斯大学 罗切斯特。质子从酸中的转移是 最常见和最重要的化学反应。这 工作将研究质子转移反应的计算 方法，并将结果与实验数据进行比较。的 控制质子能垒的个别因素 将在这些计算中探测转移。氘 取代，这改变了质子（或氘） 转移，并在确定的机制是重要的 质子转移，将被计算和比较， 试验结果 ***

9313657 Saunders Proton transfers from acids in which the ionizing proton is attached to carbon will be studied by quantum chemical methods. The energies and other properties of the separated reactants, the ion-dipole complexes, and the transition state structures for proton transfer will be calculated for a number of carbon acids that yield delocalized anions of the sort widely used in organic synthesis. A study will also be made of a prototype for oxygen acids that yield delocalized anions, acetaldehyde enol, and a comparison will be made to the carbon-centered acid, acetaldehyde. The aim of the research will be to explore the factors that influence barriers to proton transfer: acidity, heavy-atom reorganization, charge transfer, and polarizability. These gas-phase calculations will be compared to literature experimental results in both the gas-phase and solution. Calculations of isotope effects will be done on selected systems, including deprotonation of propene by hydroxide ion and elimination reactions in order to establish what level of calculation is necessary to give reasonable isotope effects, and to compare the results with experimental data in solution. %%% This grant from the Organic Dynamics Program supports the work of Professor William H. Saunders at the University of Rochester. The transfer of a proton from an acid is one the most common and most important reactions in chemistry. This work will study proton transfers reactions by computational methods and compare the results to experimental data. The individual factors that control the energy barrier to proton transfer will be probed in these calculations. Deuterium substitution, which alters the rate of proton (or deuterium) transfer and is important in determining the mechanism of proton transfer, will be calculated and compared to experimental results. ***