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71.
Previous studies have established that the extended coordination model of solvation can satisfactorily account for the variation in the transfer enthalpies of solutes in mixed-solvent systems. The model parameter relating to the solute-induced disruption of the solvent structure shows a marked dependence on the nature of the mixed solvent. In the present paper we report the transfer enthalpies of acetonitrile from water to aqueous methanol, ethanol and dimethylsulphoxide (DMSO) systems. Analysis of these in terms of the extended coordination model confirms both the model's ability to account for the experimental data, and the variability of the structural disruption parameter. The solvation parameters recovered from the analyses indicate that the net effect of acetonitrile on the solvent structure is a breaking of solvent-solvent bonds. The extent of bond breaking of the solvent increases from MeOH to EtOH. 相似文献
72.
系列单取代烷氧基-2-羟丙基-β-环糊精的合成与表征 总被引:1,自引:0,他引:1
以环氧氯丙烷和脂肪醇为原料, 通过相转移催化法合成了乙基、正丙基、正丁基和正戊基缩水甘油醚(1~4), 并利用所合成的缩水甘油醚和β-环糊精为原料, 分别在弱碱水溶液(1.5%)和强碱水溶液(30%)中制备并用硅胶柱分离出单2位取代的乙氧基、丙氧基、丁氧基和戊氧基-2-羟丙基-β-环糊精(1a~4a)和单6位取代的丙氧基、丁氧基和戊氧基-2-羟丙基-β-环糊精(2b~4b), 利用薄层色谱、红外光谱、差热扫描量热分析、质谱和核磁共振等手段对所合成的产品进行了表征. 相似文献
73.
Yun-Yun Yang 《Tetrahedron》2006,62(43):10079-10086
A Zn(OTf)2-catalyzed cascade reaction of anilines with aromatic aldehydes and carbonyl compounds was described. This one-pot three-component reaction afforded the corresponding β-amino carbonyl compounds, β-amino esters, and β-amino ketones in good to excellent yields. The reaction was also applied for the liquid-phase synthesis of β-amino carbonyl compound library using PEG as a support. 相似文献
74.
《Tetrahedron》2004,60(4):885-891
threo and erythro diastereoisomers of the constrained amino acid (βMe)Phe can be obtained separately on a multigram scale through a three-step synthesis from the corresponding Z and E isomers of 2-phenyl-4(α-phenylethylidene)-5(4H)-oxazolone. The 5(4H)-oxazolones are readily available from acetophenone and hippuric acid. The four enantiomerically pure isomers of β-methylphenylalanine, (2R,3R)-(βMe)Phe, (2S,3S)-(βMe)Phe, (2R,3S)-(βMe)Phe and (2S,3R)-(βMe)Phe, have been prepared by HPLC resolution of the racemic precursors methyl threo (or erythro)-2-benzamide-3-phenylbutanoates. 相似文献
75.
76.
We report here our findings on a new and highly efficient strategy for the synthesis of β-amino acids involving the addition of bis(O-silyl) ketene acetals on Mannich type iminium electrophiles. 相似文献
77.
Teréz Balogh 《Tetrahedron》2004,60(3):679-682
Our studies are presented to replace alcohols as solvents in reverse hydrolytic reactions catalyzed by immobilized β-glucosidase to synthesize O-substituted β-d-glucopyranosides in preparative-scale. We found that 1,2-diacetoxyethane is a suitable solvent and O-alkyl or aryl β-d-glucosides were synthesized in moderate yields (after isolation 12-19%). In these reactions proportion of glucose and glucosyl acceptor hydroxy compounds was 1:20. We suggest that 1,2-diacetoxyethane can be useful not only for alcohols but for other glucosyl donor compounds unsuitable for the role of solvent (e.g., phenols) in the synthesis of O-β-d-glucosides by reverse hydrolysis. 相似文献
78.
合成了β-芳氧基丙酸芳酯及β-芳氧基丙酰芳胺等17种化合物,经IR,UV,HNMR和元素分析确定了它们的结构,并对它们的生物活性进行了初步考察。 相似文献
79.
A series of novel hemicyanine dye-β-cyclodextrin compounds: mono-6-deoxy-β-cyclodextrin-6-[p-(p-substituted styryl)pyridium] p-totylfulfonates were synthesized by the condensation of mono-6-deoxy-β- cyclodextrin-6-(p-methyl pyridinium) p-toluenesulfonate with (un)substituted benzaldehydes. Their structures were established by 1^H NMR, IR, UV-Vis and elemental analysis. The absorption and fluorescence properties of the novel compounds were measured in solution and the photostability of a selected hemicyanine dye-β-cyclodextrin compound was also investigated. 相似文献
80.
The hexagram and arrayed β-FeOOH nanorods were first synthesized free of surfactants through the solvent-thermal method. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectrum (EDAX) and thermal gravimetric analysis (TGA) were used to characterize the as-prepared products. The TEM and FESEM images showed that hexagram β-FeOOH and arrayed rod-like β-FeOOH with an average diameter of 10-15 nm and an average length of 100 nm (aspect ratio is about 10) were prepared. Electrochemical tests show that these nanorods deliver a large discharge capacity of 277 mA h g−1 versus Li metal at 0.1 mA cm−2 (voltage at 1.5-4.2 V). Treated the as-synthesized rod-like β-FeOOH by annealing, rhombus hematite was obtained. 相似文献