EFFECTS OF SURFACTANTS ON LIGAND EXCHANGE REACTIONS IN VITAMIN B(12A) IN WATER AND IN BENZENE, INFLUENCE OF AQUEOUS MICELLES AND OF SOLVENT RESTRICTIONS
EFFECTS OF SURFACTANTS ON LIGAND EXCHANGE REACTIONS IN VITAMIN B(12A) IN WATER AND IN BENZENE, INFLUENCE OF AQUEOUS MICELLES AND OF SOLVENT RESTRICTIONS
复制标题
表面活性剂对水中和苯中维生素 B(12A) 配体交换反应的影响、水胶束的影响和溶剂限制
DOI：
10.1002/chin.197452104
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发表时间：
1974
期刊：
影响因子：
--
通讯作者：
H. V. Woert
中科院分区：
文献类型：
--
作者：
J. Fendler;F. Nome;H. V. Woert
生成速率常数Ayro和分解速率常数A在十六烷基三甲基溴化铵和十二烷基硫酸钠胶束水溶液中，以及在十二烷基丙酸铵和二（2-乙基己基）磺基琥珀酸钠的苯增溶水溶液中，测定了甘氨酸、咪唑和叠氮化钠与维生素B12 a加合物的Iapr。在水胶束的影响是相对较小的和合理的静电的考虑。利用维生素B12 a的最大吸收和甘氨酸溶解度与溶剂极性参数ε t（30）之间的线性相关性，确定了反应物在苯中表面活性剂溶解水中的有效环境取决于水和表面活性剂的浓度。维生素Bya分子被大约300个表面活性剂分子有效地从非极性溶剂中屏蔽。维生素B1·a与甘氨酸在苯中表面活性剂极性腔中相互作用的-pro和k-ppp值显著大于在本体水中的值。在溶解水的恒定浓度下，Atiapp和fc-p®随着DAP浓度的增加而增加，直到最大值，之后它们以几何学方式降低。速率增强的最大值随着水浓度的降低而增加。在较高的水和表面活性剂浓度下，维生素Bi_（2a）咪唑络合物在苯中形成的速率常数和平衡常数与在本体水中基本相同。在苯中，在0.02 M DAP和8.9 × 10-2 M水的存在下，观察到的速率常数为达到平衡的咪唑维生素Bv，加合物的咪唑浓度的增加而降低。相对于水，在最低的咪唑浓度下获得实质性的速率增强。在DAP存在下，钠尿肼与维生素Bi_（2a）在苯中相互作用的kp_（？）讨论了这些结果的意义。
Rateconstants for the formation, Ayro, anddecomposition, A.--iapr, of glycine, imidazole, and sodium azide adducts of vitamin B12a have been determined in aqueous micellar hexadecyltrimethylammonium bromide and sodium dodecyl sulfate as well as in dodecylammonium propionate and sodium di (2-ethylhexyl) sulfosuccinate solubilized water in benzene. Effects in aqueous micelles are relatively smalland are rationalized on electrostatic considerations. Using the obtained linear correlations between the absorption maxima of vitamin Bi2a, and glycine solubilities vs. solvent polarity parameters£ t (30), the effective environments of the reactants in surfactant solubi-lized water in benzene were determined to depend on the concentrations of water and of surfactants. Vitamin Bya molecule is effectively shielded from the apolar solvent by some 300 surfactant molecules. Values for-pro and k-ppp for the interaction of vitamin Bi» a with glycine in the polar cavities of surfactants in benzene are significantly greater than those in bulk water. At constant concentration of solubilized water Atiapp and fc-p®» increase with increasing DAP concentration up to a maximum after which they decrease logarithmically. The maxima of rate enhancements increase with decreasing water concentrations. At relatively high water and surfactant concentra-tions the rate and equilibrium constants for the formation of the imidazole complex of vitamin Bi2a in benzene are essentially identicalwith those in bulk water. In benzene in the presence of 0.02 M DAP and 8.9 X 10-2 M water the observed rate constant for the equilibrium attainment of the imidazole vitamin Bv, a adduct decreases logarithmically with increasing concentration of imidazole. Substantialrate enhancement, with respect to water, is obtained at the lowest imidazole concentration. Values of kp®® and k-Ppp for the interactionof sodiumazide with vitamin Bi2a in benzene in the presence of DAP are markedly smaller thanthose in water. Significance of these results is dis-cussed.