四种叠氮铵类离子液体的合成及其物性研究

Synthesis and Physicochemical Properties of Four Azidoammonium-Based Ionic Liquids

以N,N-二甲基-2-叠氮乙胺（DMAZ）为起始物,通过烷基化和复分解反应,合成了四种以二氰胺根为阴离子的叠氮类离子液体（[Rdmaz][N（CN）2],R=乙基（e）,正丁基（b）,正己基（C6）,正辛基（C8））,测定了这些离子液体在一定温度范围内的密度、动力黏度和摩尔定压热容等物性,讨论了烷基链长对其物性的影响。结果发现,随烷基链中碳数的增加,离子液体的密度减小、动力黏度和摩尔定压热容增加。密度和温度之间呈线性关系;动力黏度与温度之间满足Vogel-Fulcher-Tamman（VFT）方程;摩尔定压热容与温度之间可用方程C p,m=a＋bT＋cT2拟合。四种离子液体均没有熔点,只有一个玻璃化转变温度（T g）,[edmaz][N（CN）2]、[bdmaz][N（CN）2]、[C6dmaz][N（CN）2]和[C8dmaz][N（CN）2]的T g分别为-102,-92,-89,-91℃。四种离子液体的分解温度在241~242℃之间,与烷基链长基本无关。

Four ionic liquids with formula of [Rdmaz][N（ CN）2],R = ethyl（ e）,n-butyl（ b）,n-hexyl（ C6） and n-octyl（ C8）,were synthesized through a metathesis reaction of quaternized N,N-dimethyl-2-azidoethylamine（ DMAZ） with different alkyl chain length with silver dicyanamide. The density,dynamic viscosity and thermal properties of these ionic liquids were measured over a wide temperature range. The effect of the alkyl chain length was discussed on the physicochemical properties. Density decreases while dynamic viscosity and molar heat capacity increase with increasing number of carbon atoms in the alkyl chain. The density shows a linear decrease with temperature,and the dynamic viscosity decreases with temperature following the Vogel-Fulcher-Tamman（ VFT） equation. The molar heat capacity（ C p,m） increases with temperature following the equation C p,m= a ＋ bT ＋ cT2. No melting points were found for these four ionic liquids except for a glass transition temperature（ T g）. The T g values were-102 ℃ for [edmaz][N（ CN）2],-92 ℃ for[bdmaz][N（ CN）2],-89 ℃ for [C6dmaz][N（ CN）2],and-91 ℃ for[C8dmaz][N（ CN）2]. The decomposition temperatures of these four ionic liquids range from 241 ℃ to 242℃,independent of the alkyl chain length.