Fourier Transform Infrared Study on Hydrogen Bonding Species of Carboxylic Acids in Supercritical Carbon Dioxide with Ethanol
Fourier Transform Infrared Study on Hydrogen Bonding Species of Carboxylic Acids in Supercritical Carbon Dioxide with Ethanol
复制标题
超临界二氧化碳与乙醇中羧酸氢键形态的傅里叶变换红外研究
DOI：
10.1021/jp984604p
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发表时间：
1999
影响因子：
2.9
通讯作者：
Y. Arai
中科院分区：
文献类型：
--
作者：
Morio Yamamoto;Y. Iwai;T. Nakajima;Y. Arai
超临界流体萃取技术作为一种新型的分离技术，近年来受到了广泛的关注。用傅里叶变换红外光谱（FTIR）测定了羧酸（乙酸和棕榈酸）在超临界CO{sub 2}中二聚反应的平衡常数和羧酸与乙醇间氢键物种的数量。实验温度为308.2- 313.2K，压力为10.0- 20.0MPa。羧酸分子的C{double_bond}O伸缩带是一个值得注意的谱带。在二元体系（超临界CO{sub 2} +羧酸）中，羧酸单体与二聚体的二聚反应平衡常数随压力和温度的升高而减小。棕榈酸的平衡常数大于乙酸。在三元体系（超临界CO{sub 2} +羧酸+乙醇）中，随着乙醇摩尔分数的增加，超临界CO{sub 2}中羧酸与乙醇之间的氢键物种数量增加。此外，作者证实，乙醇作为超临界CO{sub 2}中的增溶剂与羧酸和乙醇之间的氢键物种的数量有关。
Supercritical fluid extraction has been given much attention recently as one of the new separation technologies in the chemical industry. Fourier transform infrared (FTIR) spectroscopy has been used to determine the equilibrium constants of the dimerization for carboxylic acid (acetic acid or palmitic acid) and the amount of hydrogen bonding species between carboxylic acid and ethanol in supercritical CO{sub 2}. Experiments were carried out at 308.2--313.2 K and 10.0--20.0 MPa. The noticeable band was the C{double_bond}O stretching band for carboxylic acid. In the binary system (supercritical CO{sub 2} + carboxylic acid), the equilibrium constants of the dimerization between the carboxylic acid monomer and dimer decrease with increasing pressure and temperature. The equilibrium constants of palmitic acid are larger than those of acetic acid. In a ternary system (supercritical CO{sub 2} + carboxylic acid + ethanol), the amount of hydrogen bonding species between carboxylic acid and ethanol in supercritical CO{sub 2} increases with the increasing mole fraction of added ethanol. Furthermore, the authors confirm that the solubility enhancement by ethanol used as an entrainer in supercritical CO{sub 2} related to the amount of hydrogen bonding species between carboxylic acid and ethanol.