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丙氨酸Ala及二肽Ala-Ala和三肽Ala-Ala-Ala的三氟乙酰酐甲酯衍生物能在气相色谱手性固定相Chirasil-Val上被分别分离为2个、4个和8个对映体。立体异构体和手性固定相的立体选择相互作用既受到焓也受到熵的控制。每增加一个Ala单位,相互作用焓近似地增加一个常量。相互作用在溶质的全分子范围内进行,但以末端所起的作用最大。三肽Ala-Ala-Ala中DDD,LLL等对映体的流出次序和它们的焓值大小比较不相一致,DDD/LLL对的分离因子α随温度的增加反而增加,在更低的温度下观察到了这两个对映体的峰序颠倒现象,因此推断在一定条件下存在着相互作用熵起主导作用的可能性。
The trifluoroacetyl anhydride methyl ester derivatives of alanine Ala and dipeptide Ala-Ala and the tripeptide Ala-Ala-Ala were separated into 2, 4 and 8 respectively on the chiral stationary phase Chirasil-Val Enantiomers. Stereoselective interactions between stereoisomers and chiral stationary phases are controlled both by enthalpy and entropy. For every additional Ala unit, the enthalpy of interaction approximately increases by a constant. The interaction takes place within the full molecular range of the solute, but the effect is greatest at the end. In the tripeptide Ala-Ala-Ala, the DDD and LLL enantiomers outflow order and their enthalpy values are not consistent. The separation factor α of DDD / LLL pairs increases with increasing temperature. At lower temperatures The peak-to-peak inversion of the two enantiomers was observed, so it is inferred that under certain conditions there is a possibility that the entropy of interaction plays a dominant role.