Assessing the Temperature-Dependent Tunable Polarity of N,N-Dimethylcyclohexylamine (DMCHA) and Water Mixtures

: The promise of switchable solvents as green solvent alternatives lies in the ability to drastically alter their properties based on an external trigger. Switchable hydrophilicity solvent N , N -dimethylcyclohexylamine, DMCHA, is known to change properties based on both CO 2 addition and variations in temperature, both in the presence of water. While the impact of temperature has been observed via changes in water solubility, the solvent properties underlying these observations have not been quanti fi ed. Kamlet − Taft solvatochromic parameters ( α , β , and π * ) and dielectric constants for DMCHA and DMCHA − water mixtures were measured across a temperature range of 25 − 60 ° C. Temperature swing e ff ects of DMCHA in addition to CO 2 -switching capabilities were validated and quanti fi ed on the Kamlet − Taft polarity scale. Notably, binary mixtures of water in DMCHA show promising tunability in terms of its β and π * parameters induced by moderate variations in temperature. Potential applications for this CO 2 -switchable and temperature-tunable solvent are discussed.

可切换溶剂作为绿色溶剂替代品的前景在于其能够基于外部触发因素大幅改变自身性质。可切换亲水性溶剂N,N -二甲基环己胺（DMCHA）已知在有水存在的情况下，会基于二氧化碳的加入和温度变化而改变性质。虽然通过水溶性的变化已经观察到温度的影响，但这些观察结果背后的溶剂性质尚未被量化。在25 - 60°C的温度范围内测量了DMCHA以及DMCHA - 水混合物的Kamlet - Taft溶剂化显色参数（α、β和π*）以及介电常数。除了二氧化碳切换能力外，还在Kamlet - Taft极性标度上验证并量化了DMCHA的温度摆动效应。值得注意的是，DMCHA中的水二元混合物在由温度适度变化引起的β和π*参数方面显示出有前景的可调性。讨论了这种二氧化碳可切换且温度可调节溶剂的潜在应用。