- 期刊
烴基乙酸及其離子構形異構物與分子內氫鍵理論研究
Theoretical Study of Relative Stability of Structural Conformers and Intramolecular Hydrogen Bonding of Glycolic Acid and Its Anions
摘要
以Gaussian 98套裝軟體選用B3LLYP層級以6-311+G(2d,p)及6-31G**為基底函數二種方法，對烴基乙酸及其離子進行構形異構物及分子內氫鍵研究。以最佳化幾何優選及頻率計算，分別求得七個烴基乙酸及四個負一價離子構形異構物，最穩定的構形皆擁有分子內氫鍵。運用B3LYP/6-311+G(2d,p)法求得過渡態及各構形間轉變過程中之能障。為了更進一步探討分子內氫鍵，我們運用幾何優選後的構形異構物間的能差及“區域化鍵分佈分析”二種計算方法來分辨分子內氫鍵的強弱。所有計算結果顯示，烴基乙酸及其離子形成穩定態的結構與分子內氫鍵有密切關係。
並列摘要
The 6-311+G(2d,p) and 6-31G** basis sets with B3LYP level selected from Gaussian 98 package has been employed for studying the relative stabilities of their conformers and the intramolecular hydrogen bonding of glycolic acid and its anions. Seven stable conformers of glycolic acid and four stable conformers of its anions have been found by the optimization and confirmed by vibrational frequency analysis. The most stable conformer of glycolic acid and anions are both equipped with intramolecular hydrogen bond. The transition states and energy barriers of the conformerization processes were investigated by B3LYP/6-311+G(2d,p) method. The localized hydrogen bonding analysis is than applied to further evaluate quantitatively the strength of intramolecular hydrogen bonding, in addition to the qualitative estimate based on the energy differences of various optimized structures. All the evidences show that the relative stability among conformers of glycolic acid and its anions are closely related to the intramolecular hydrogen bonding effect.