自溶液中的吸附 VII: 硅胶自环己烷中吸附醇,酮和酯

The adsorption isotherms of some monofunctional alcohols, ketones and esters from cyclohexane onto silica gel have been determined at 30`C and 10`C. The silica gel used bad a BET area of 417 m2/g and an average pore radius of 45A. The concentrations of free and associated hydroxyls on the silica gel were 1.4 and 4.1/100A^2 respectively. The adsorption order is cyclohexanol>n-octyl alcohol>cyclohexanone>methyl isobutyl ketone>n-propyl acetate=n-amyl acetate. The adsorption decreases with increasing temperature as normal. Except at very low concentrations, the isotherms can be represented by the Langmuir equation. The limiting adsorption, nms, on the silica gel does not accord with the stoichiometric ratio (1:1) between the free surface hydroxyl groups of the adsorbent and the adsorbate. In addition to surface conditions and the functional group of the adsorbate, it seems that the limiting adsorption is also controlled by the other factors, including temperature, solvent, and, sometimes the chain length of the adsorbate. The standard free energy (ΔG0) and standard enthalpy (ΔH0) of the adsorbates in adsorptien processes have been determined from the Langmuir parameters. The results indicate that the absolute value of ΔH0 is higher than that of ΔG0 (in other words, standard entropy ΔS0 is negative), as in the case of the adsorption of gases. Since there is practically no difference in ΔG0 or ΔH0 of adsorption between alcohols or esters, it is suggested that in dilute solution only the polar groups take part in adsorption, and the hydrocarben chains remain in solution during the adsorption process. For ketones, the absolute values of ΔG0 and ΔH0 are somewhat lower for methyl isobutyl ketone than that for cyclohexanone. A possible explanation is that in the adsorbed state the isobutyl chain of the methyl isobutyl ketone may somewhat close to the surface and thus decreases the adsorption and changes the ΔG0 and ΔH0.     

C60与环己烷及环己烯离子体系的气相反应

在气相条件下研究了C60与环己烷及环己烯的离子-分子反应。C60可与上述体系中多种离子发生反应, 生成相应的加合离子, 表现出C60化学性质的活泼性和多样性。C60与C4H7^+和C5H7^+离子反应可能生成[2+4]环加成的加合离子。     

吸附分子结构单元与溶液吸附常数的关系

本工作利用硅胶自环己烷中附醇.酮.酯. 活性炭自环己烷中吸附芳香化合物的实验结果计算证明,这些化合物吸附的Henry常数K(K=n^s~m.b)~i,式中n^s~m. b 为Langmuir等温式中极限吸附量,b为与吸附热有关的常数,n~i为构成分子的i 结构单元的Henry常数,这一结果给出了在一定条件下预示吸附等温线的可能性.     

TBP"探针"法与荧光光谱法测定环己烷最低激发单态G值的比较

By using tri-Bu Phosphate (TBP) as an energy acceptor, G value of lowest excited singlet state of cyclohexane has been determine under g irradiation It was found that in N2 atmosphere when the dose approaches zero G(S1) equals 1.3 ?0.2. Which is in harmony with the G value determine by fluorescence method. Rate constant of energy transfer from lowest excited singlet state of cyclohexane to TBP was found to be 0.6 ?1010 mol-1譻-1, which is in harmony with kses. The influence factor on the determination of yields of excited states and rate constant of energy transfer was discussed. The excited triplet state of cyclohexane has been studied, G value of excited triplet state of cyclohexane is 0.26 ?0.04 and t x 6 ns.     

模拟细胞色素P-450和仿生氧化反应研究III. 有关用TPPFe(III)Cl及TPPMn(III)Cl催化的环己烷充氧化反应机理的初步探讨

本文研究了ArIO充氧化环己烷的反应体系。在TPPFe(III)Cl及TPPMn(III)Cl催化下进行了动态UV-Vis谱和ESR分析,提出了二种催化体系可能由二种不同递氧中间体的反应机理。     

模拟细胞色素P-450的仿生氧化反应的研究 I:氯合5,10,15,20-四苯基卟吩合铁(III)催化下不同亚碘酰芳烃及其衍生物的结构对环己烷充氧化反应的影响

在氯合5,10,15,20-四苯基卟吩合铁(III)[TPPFe(III)Cl]催化下, 带有不同取代基的亚碘酰苯和亚碘酰苯的衍生物作充氧化剂对环己烷进行了仿生单充氧化反应的研究.取代亚碘酰苯中对位取代基的电子效应和间位取代基的电子及立体效应对氧化产物环己醇的产率有良好线性相关性. 亚碘酰苯的衍生物苯亚碘酸二醋酐与苯亚碘酸单对甲苯磺酸酐对环己烷的充氧化能力和邻、间、对亚碘酰苯甲酸与邻亚碘酰苯甲酸酯相似, 环己醇产率接近零. 从而提出亚碘酰苯甲酸及邻亚碘酰苯甲酸酯存在分子内或分子间I(oh)oco成键结构的论点.     

四氯化碳和吡啶对苯和环己烷中正子素生成的影响

研究了在含不同浓度电子清除剂CCL_4或正穴清除剂吡啶的苯溶液和环己烷溶液中o-Ps强度的变化。结果表明,环己烷中电子和正离子的迁移率是很高的,苯中的迁移率也较高,但比环己烷中的小些。由我们导出的有关正穴清除剂使o-Ps强度增加的关系式表明,o-Ps强度的增强或抑制是电子清除和正穴清除这两个过程竞争的结果。     

电解质在非水混合溶剂中的溶解度和溶剂化数的研究-盐-甲醇-非电介质体系

本文测定了KClO3, NaNO3, NaNO2 三种盐在甲醇-苯, 甲醇-环己烷, 甲醇-四氯化碳和甲醇-二氧六环以及KCl 在甲醇-苯和甲醇-甲苯中的溶解度.它们与非电解质的摩尔分数Xne 的关系符合经验公式计算得到各种盐的甲醇化数: KClO3 为7.1 , NaNO3 为6.4 , NaNO2 为5.8 . 从单骀溶剂化模化模型出发,应用改进的Born 公式, 推导出第二介质参数k'的理论计算公式. 计算的k'和实验的k 数值相近, k'对k 有一定的预示.