摘要
利用竞争紫外-可见光谱法研究了温度对β-环糊精(β-CD)包合不同结构硫醇客体分子作用的影响。结果表明,在不同温度下β-CD与硫醇均可发生包合作用,并分别测定了25.0、30.0、35.0、40.0及50.0℃下正构硫醇和异构硫醇与β-CD所形成包合物的稳定常数。正丁硫醇与β-CD包合物的稳定常数分别为:49.37、66.39、93.88、124.5和197.61L/mol,包合过程的ΔG、ΔH及ΔS分别为-9.661kJ/mol、35.85kJ/mol、152.63J/(mol.K);异丁硫醇与β-CD包合物的稳定常数分别为:326.0、364.6、415.3、472.2和592.4L/mol,而包合过程的ΔG、ΔH及ΔS分别为-14.34kJ/mol、19.35kJ/mol、112.98J/(mol.K)。研究发现,β-CD对不同结构硫醇的包合能力均随温度的升高而增强,且在研究的温度范围内包合过程均可自发进行,且是吸热的熵控制过程。硫醇分子烷基链疏水部分水壳层的破坏,使得自由运动的粒子数增加,且进入β-CD疏水空腔的烷基运动自由度的增加是引起熵值增加的主要原因。
The influence of temperature on encapsulation of various vip mercaptans in β-cyclodextrin （β- CD） was investigated by the competitive UV-Vis spectrophotometric method. The results indicated that β-CD could include different mercaptans to form inclusion compounds at different temperatures. The inclusion stability constants of β-CD including 1-butanethiol at 25.0, 30. 0, 35.0, 40. 0 and 50.0 ℃, were 49.37, 66.39, 93.88, 124.5, and 197.61 L/mol, respectively, and those of β-CD wrapping 2-methyl-1- propanethiol were 326.0, 364.6, 415.3, 472.2, and 592. 4 L/mol, respectively. The thermodynamic parameters ΔG, ΔH, and ΔS of the inclusion process were -9.661 kJ/mol, 35.85 kJ/mol, and 152.63 J/（mol . K） for 1-butanethiol, and - 14.34 kJ/mol, 19. 35 kJ/mol, and 112.98 J/（mol . K） for 2-methyl-l-propanethiol, respectively. It was found that the inclusion abilities of β-CD encapsulating various mercaptans were all enhanced with the increase of temperature; β-CD could spontaneously include various mercaptans in the temperature range studied, and the inclusion process was endothermic and controlled by entropy. The outer water shell of the hydrophobic alkyl of the mercaptan was destroged, causing the increase of the number of free molecules and the increase of the degree of freedom for the hydrophobic alkyl of the mercaptan inserted into the cavity β-CD, which contributed to the increase of entropy.
出处
《应用化学》
CAS
CSCD
北大核心
2007年第10期1201-1205,共5页
Chinese Journal of Applied Chemistry
关键词
Β-环糊精
硫醇
包合作用
温度
β-cyclodextrin, mercaptan, inclusion, temperature
