1-烷基-4-氨基-1,2,4-三唑硝酸盐含能离子液体的蒸气压及其摩尔汽化焓的理论研究

合成了1-烷基-4-氨基-1,2,4-三唑硝酸盐含能离子液体(RATZ]NO₃),并通过核磁和红外进行了结构表征；采用Gaussian09/B3LYP/6-311+G(d,p)密度泛函理论,计算了RATZ]NO₃的离子间相互作用能及摩尔体积；在298 K-323 K温度范围内,测定了不同配比RATZ]NO₃-EtOH混合溶液的饱和蒸气压,其中乙醇摩尔分数分别为0.984、0.996、0.999以及1.000。系统研究了RATZ]NO₃-EtOH混合溶液的饱和蒸气压、RATZ]NO₃的蒸气压及摩尔汽化焓与温度、离子间相互作用能以及结构之间的关系。结果表明：RATZ]NO₃-EtOH混合溶液的饱和蒸气压随着温度的升高、离子间作用能的减小以及阳离子体积的增大而增大,其沸点比纯溶剂高,且在298 K-323 K温度范围内RATZ]NO₃的平衡蒸气压均低于250 mPa,因此说明含能离子液体具有不挥发性,蒸气压极低,并通过理论计算得到的离子间相互作用能及体积,解释了RATZ]NO₃的摩尔汽化焓随烷基链增长而降低的原因。

Theoretical Study on Vapor Pressure and Molar Enthalpy of Vaporization of 1-Alkyl-4-Amino- 1, 2, 4-Triazolium Nitrate Energetic Ionic Liquids

1-alkyl-4-amino-1,2,4-triazolium EILs with anions based on nitrate (NO_3^-) are synthesized. The structure are characterized by ^₁H NMR and FT-IR. Their interaction energies of ion pairs and standard molar volume are calculated by DFT/B3LYP/6-311+G(d,p) and further researched. The saturated vapor pressure of different molar ratio (x_A,EtOH=0.984, 0.996, 0.999 and 1.000) of the RATZ]NO₃-EtOH mixed solution are measured between 303-353 K. The relationship between the saturated vapor pressure of RATZ]NO₃-EtOH, vapor pressure and molar enthalpy of vaporization of RATZ]NO₃ and temperature (303 to 353) K, molecular structure, and the interaction energies of ion pairs are discussed systematically. The results show that saturated vapor pressure of RATZ]NO₃-EtOH increased as temperature went up and increased with the increase of the cation size and the decrease of interaction energies of ion pairs; The results also indicate that the boiling points of the RATZ]NO₃-EtOH mixed solution are higher than the pure solvent (EtOH), and the vapor pressure of vaporization of RATZ]NO₃are lower than 250 mPa at 303-353 K. It shows that the ionic character leads to the negligible vapor pressure. Finally, the reason of the molar enthalpy of vaporization of RATZ]NO₃ decreased with the elongation of the alkyl chain length on cation is explained by the cation size and interaction energies of ion pairs through calculation.