Theoretical Enthalpies of Formation of [AA]X and [AAE]X Type Amino Acid Ionic Liquids

详细信息    查看全文

• 作者：Lin-Lin Dong ; Ling He ; Guo-Hong Tao ; Ming Huang ; Changwei Hu
• 刊名：Journal of Chemical & Engineering Data
• 出版年：2013
• 出版时间：May 9, 2013
• 年：2013
• 卷：58
• 期：5
• 页码：1176-1185
• 全文大小：477K
• 年卷期：v.58,no.5(May 9, 2013)
• ISSN：1520-5134

文摘

The theoretical enthalpies of formation of 108 [AA]X and [AAE]X type amino acid ionic liquids composed of 12 amino acid cations (Gly⁺, GlyC₁⁺, Ala⁺, AlaC₁⁺, Pro⁺, ProC₁⁺, Phe⁺, PheC₁⁺, Val⁺, ValC₁⁺, Leu⁺, LeuC₁⁺) with 9 different anions (Cl^{鈥?/sup>, BF₄鈥?/sup>, PF₆鈥?/sup>, N(CF₃SO₂)₂鈥?/sup>, CH₃CO₂鈥?/sup>, CF₃CO₂鈥?/sup>, CF₃SO₃鈥?/sup>, HSO₄鈥?/sup>, SO₄2鈥?/sup>) were studied. A systematic theoretical study on these amino acid ionic liquids was performed by quantum chemistry calculation using the Gaussian03 program. The geometric optimization and the frequency analyses were carried out using the B3LYP method with the 6-31+G** basis set. Their calculated enthalpies of formation were derived from the single point energies carried out with the MP2/6-311++G** level of theory. The enthalpies of formation of these amino acid ionic liquids were calculated to be from 鈭?577.0 kJ路mol鈥? to 鈭?11.3 kJ路mol鈥?. The negative values show their stable thermodynamics status. The energy differences between the predicted enthalpies of formation of each amino acid salt and those of their two neutral precursors were studied. The experimental enthalpies of formation of five amino acid ionic liquids [Gly]Cl, [Ala]Cl, [Ala]HSO₄, [Pro]CF₃CO₂, and [Pro]CF₃SO₃ were obtained from the corresponding energies of combustion determined by the bomb calorimetry method. The experimental enthalpies of formation are in good agreement with corresponding theoretical results. This study provides an effective theoretical method to predict the thermodynamic stability of the preparation of new amino acid ionic liquids.}