共查询到20条相似文献,搜索用时 125 毫秒
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通过糖单元6-位羟基的保护和去保护,运用区域选择性方法合成了6种新型多糖类氨基甲酸酯衍生物,分别为纤维素/直链淀粉-[2,3-二(3,5-二甲基苯基)-6-环己基]氨基甲酸酯、[2,3-二(3,5-二氯苯基)-6-环己基]氨基甲酸酯及[2,3-二(4-氯苯基)-6-环己基]氨基甲酸酯,并将其涂敷在氨丙基硅胶的表面制备HPLC手性固定相.利用1H-NMR与FTIR光谱技术对所合成衍生物进行结构表征和分析,并应用HPLC法评价其对于9种手性化合物的手性识别能力.通过与以手性识别能力高而著称且含有单一取代基的纤维素/直链淀粉-三(3,5-二甲基苯基氨基甲酸酯)等手性固定相的对比分析表明,所合成新型手性固定相对于某些对映体显示出更优的手性识别能力.由进一步分析表明,糖单元2-、3-和6-位取代基的性能对于纤维素和直链淀粉氨基甲酸酯类衍生物的手性识别能力均具有较大影响. 相似文献
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高效液相色谱手性固定相法分离取代环己酮及取代环己醇的对映体 总被引:1,自引:0,他引:1
在4种自制的涂敷型纤维素衍生物手性柱,即纤维素三苯甲酸酯(CTB)、纤维素三(4-甲基苯甲酸酯)(CTMB)、纤维素三苯基氨基甲酸酯(CTPC)和纤维素三(3,5-二甲基苯基氨基甲酸酯)(CDMPC)与小分子的Prikle型(S,S)-Whelk—O1手性柱上对取代环己酮及取代环己醇进行了对映体分离。研究了溶质的立体结构因素对手性分离的影响,并初步探讨、比较了溶质在这两种手性柱上的手性识别的机理。结果发现,在(S,S)-Whelk—O1柱上溶质与固定相之间的吸引作用是手性识别的主要原因,而对于纤维素衍生物手性柱,溶质的空间结构在手性空腔中的空间适应性可能是手性识别的关键。 相似文献
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键合型纤维素-苯基氨基甲酸酯手性固定相的制备及用于对映异构体拆分 总被引:1,自引:0,他引:1
采用化学键合法,利用4,4′-二苯基甲基二异氰酸酯作间隔臂,通过纤维素葡萄糖单元上2、3或6-位上的羟基将纤维素衍生物键合在氨丙基硅胶上,制备了键合型纤维素-苯基氨基甲酸酯手性固定相.同时,以微晶纤维素和苯基异氰酸酯为原料,合成了纤维素-三苯基氨基甲酸酯,并以未修饰的硅胶为载体,制备了涂敷型纤维素-三苯基氨基甲酸酯手性固定相.分别对键合型和涂敷型两类手性固定相进行了表征,并首次在纤维素-苯基氨基甲酸酯手性柱上拆分了安息香. 相似文献
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高效液相色谱中的纤维素衍生物手性固定相 总被引:10,自引:6,他引:10
本文评述了高效液相色谱中的纤维素衍生物手性固定相,介绍了纤维素衍物生的主要类型,阐述了纤维素省生物手性固定相的光学拆分机理,并评述了该手性固定相在医药品、生化和有机中间体的分析及对映体制备等方面的应用。引文64篇。 相似文献
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Raoult's law as applied to binary solvent mixtures 总被引:1,自引:0,他引:1
The inapplicability of the original statement of Raoult's law to binary solvent mixtures has been known for many years. An appropriate form for binary solvent mixtures is developed from the fundamental thermodynamic concept of fugacity, and is shown to be quantitatively applicable to the water+tetrahydrofuran solvent system and qualitatively applicable to the results which have been obtained for other aqueous organic solvent mixtures. 相似文献
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《The Journal of chemical thermodynamics》2003,35(10):1623-1634
The densities of solutions of cholesterol in several primary amines and 1-chloroalkanes have been measured at T=298.15 K. The values of partial molar volumes of cholesterol have been calculated and the effect of solute–solvent and solvent–solvent interactions on the partial molar volume of cholesterol have been discussed. For the solvents studied the increase of alkyl chain length enhances the dispersion solvent–solvent interactions and weakens (per one cholesterol molecule) the contribution of dispersion forces in the solute–solvent interactions. Both effects bring about an increase in the partial molar volume of cholesterol with increasing the alkyl chain length. The relation between interaction volume of cholesterol (s.p.t. calculation) and the alkyl chain length have been also discussed. 相似文献
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Tanshen, the rhizome of Salvia miltiorrhiza Bunge, is a famous Traditional Chinese Medicine for multiple therapeutic remedies. This work presents the isolation and purification of tanshinone I and tanshinone IIA from the extract of the rhizome of S. miltiorrhiza by using high‐speed counter‐current chromatography (CCC) without presaturation of the two‐phase solvent mixture. The CCC method combines the results of CCC solvent system selection and components analyses of solvent mixture by GC, and thus it is possible to add accurately each individual solvent to prepare single saturated solvent phase without presaturation. The optimum CCC solvent system is a system of hexane–ethyl acetate–ethanol–water (8:2:7:3, v/v), which has been determined by usual solvent system selection and CCC runs. As a result, over 98% pure tanshinone IIA and over 94% pure tanshinone I have been obtained by using less solvent volume. Their structures have been identified by ESI‐MS, NMR spectra. 相似文献
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Solvation characteristics in ternary solvent mixtures have been studied by monitoring the solvent-sensitive electronic absorption band of a ketocyanine dye in two ternary solvent mixtures, water + ethanol + benzene and water + ethanol + cyclohexane, in which one of the pairs are partially miscible. Investigations have been done in a completely miscible region including the binodal curve. The maximum energy of absorption (E) of the solute in a ternary solvent mixture differs significantly from the mole fraction average of the E-values in the component solvents. Results in the corresponding binary solvent mixtures also show a deviation of the E-value from the mole fraction averaged E-values, indicating preferential solvation by a component solvent. The results in ternary solvent mixture have been explained in terms of a realistic model of solvation using the results on binary solvation. 相似文献
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G. N. Bondarenko M. N. Efimov L. M. Zemtsov G. P. Karpacheva 《Polymer Science Series A》2009,51(8):864-869
Complexation in the polyacrylontrile-amide solvent-PtCl4 solvent system has been studied by IR and electronic absorption spectroscopy. It has been shown that Pt is involved in complexation
between the amide group of the solvent and the nitrile group of the polymer, thereby promoting retention of the residual solvent
in it. Upon full removal of the solvent, Pt forms complexes with the conjugated system of C=N bonds being formed. 相似文献
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Yevgen Posokhov Konstantin SytnikKasim Ocakoglu Mahmut Ku? Siddik Içli 《Journal of photochemistry and photobiology. A, Chemistry》2012,227(1):25-31
Spectral-luminescent properties of the newly synthesized 2-(3′-coumarinyl)-5-(2′-(R-amino)-phenyl)-1,3,4-oxadiazoles has been investigated in solvents of various polarity and hydrogen-bonding ability. It has been found that for all the studied compounds no excited state intramolecular proton transfer occurs despite the presence of coumarinyl fragment - electron acceptor effect of the coumarinyl fragment is not sufficient to increase the excited state acidity of the amino group. It has been found that the absorption spectra of the studied compounds shift to higher energy with increase in solvent polarity, whereas corresponding fluorescence spectra shift to lower energy with solvent polarity increase. It has been suggested that long-wavelength shifts of the fluorescence spectra of the studied compounds with increase in solvent polarity is caused by the solvent relaxation. The observed solvent relaxation effect allow us to propose some of the studied compounds as potential probes to monitor changes in solvent relaxation in low-polar media and as potential probes for rigidochromic effect. 相似文献
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A solvent venting technique for injection of volumes up to 1 μl on 50 μm i.d. SFC columns has been compared to direct injection methods. The peak broadening and peak splitting observed with direct injection have been examined and found to be related to the starting pressure, the column temperature, and the sample solvent, in addition to the sample volume. The solvent venting technique removed peak splitting and improved the column efficiency. With a proper selection of experimental conditions, the sample recovery was 100%. The major part of the solvent was eluted in 15–20 s. Several applications have been demonstrated. 相似文献
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Nanosecond fluorescence spectroscopy has been used to study the interaction of 2-anilinonaphthalene with polar solvent molecules which is shown to result in stoichiometric complex formation at low polar solvent concentrations. This is followed by reorientation of the solvent cage when the concentration of polar solvent is high. 相似文献
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《Spectrochimica Acta Part B: Atomic Spectroscopy》1987,42(5):677-688
Solvent plasma loads of nine solvents, including water, have been determined for a wide range of nebulization conditions. The measurements were accomplished by making use of the so-called “continuous weighing method”. In addition, the tolerance of medium power inductively coupled plasmas (ICP) to solvent loading has been established. The organic solvents studied were selected on the basis of their significance for direct ICP analysis of organic solvent solutions using atomic emission spectrometry. The results show that the solvent saturation vapour pressure governs the solvent plasma load, whereas the evaporation factor dominates the distribution of the solvent over the liquid and vapour phase at the exit of the spray chamber. 相似文献