基于LFHB 理论模型关联和预测醇+惰性溶剂的1H NMR 化学位移

运用含氢键缔合的格子流体状态方程(LFHB), 仅用一个参数关联了一元醇-惰性溶剂共17个体系29套1H NMR化学位移数据. 并且用关联参数成功预测了不同温度下丁醇+环己烷的化学位移. 所得结果与化学缔合理论的结果进行了比较. 对于某些体系在稀浓度范围LFHB的计算氢键缔合度要低于化学缔合理论的结果. 并且分析了LFHB理论中的物理参数和化学参数对于缔合度计算的不同影响.     

丙酮肟与某些芳烃相互作用的~1H核磁共振研究

Hatton和Richards通过对酰胺分子的~1H NMR谱溶剂效应的研究,提出了DMF与苯生成分子络合物的模型.如果络合物按1:1生成,那么将出现一个“饱和点”,在这点上甲基的芳香溶剂诱导位移(ASIS)的变化趋势或程度将出现一个明显的变化,事实上随着苯的摩尔分数从0到1逐渐增加时,化学位移总是有规则的逐渐移向高场.这就显示了分子络合物观点的局限性.它能被一些研究者所支持和接受,是因为它能够解释两个甲基共振峰先重合而后又分离的现象.     

丙酮肟与某些芳烃相互作用的1H核磁共振研究

~1H NMR spectra of acetoxime have been measured as a function of the mole fraction of certain aromatic hydrocarbons in mixed solvent of CCl_4 and benzene or toluene. It has been found that the chemical shifts of the two methyl groups in acetoxime and of benzene or toluene move upfield gradually in the mixed solvent as the mole fraction of aromatic component increases. The moving rate of the resonance absorption line of the two methyl groups in acetoxime are different. The △δ of β-CH_3 is larger than that of α-CH_3. The absorption line of the two methyl groups is a singlet in CCl_4 and splits to a doublet when the concentration of benzene or toluene in the solvent is higher than 30% (mole/mole). The experimental results also show that the extent of upfield shifts of either the methyl groups in acetoxime or the aromatic hydrogens are reduced when a hydrogen of benzene is substituted by methyl group. All of the chemical shifts can be correlated with a linear equation as δ=A+Bx, Where, x is the mole fraction of benzene or toluene in the mixed solvent. The correlation coefficients R are approximately equal to -1.     

Pt/WO_3/ZrO_2催化甘油选择性脱羟基制1,3-丙二醇反应的溶剂效应

 考察了不同溶剂中 Pt/WO3/ZrO2 催化剂催化甘油加氢制 1,3-丙二醇的反应性能. 结果表明, 质子溶剂乙醇和水有利于甘油转化为 1,3-丙二醇. 含有乙醇或水的二元混合溶剂表现出明显的溶剂组分协同效应, 使用混合溶剂时 1,3-丙二醇选择性超过使用单一溶剂, 而且混合溶剂的组成对反应性能影响很大.     

2,4,6-三(芳基氨基)-1,3,5-三嗪衍生物的合成方法和微波效应研究

用碳酸氢钠作扑酸剂,将芳香胺和氰尿酰氯在1,4-二氧六环中回流状态下反应合成了7个2,4,6-三(芳基氨基)-1,3,5-三嗪衍生物,其中6个是新化合物.与已有文献报道的方法相比,条件温和,易于操作,收率高.所合成化合物的结构通过元素分析,FAB-MS,IR确定.在二氧六环:DMF为10:3(V:V)的混合溶剂中,研究了在微波照射下和常规加热下反应速率的差异.结果表明,微波加热比常规加热下的反应速率至少高10倍以上.     

Stereochemistry Control in Direct 1α-Hydroxylation of 5,6-trans-Vitamin D3 by Solid Support

1α-Hydroxyvitamin D3 1 (1α-hydroxycholecalciferol) is a biologically active form ofvitamin D3 2 which exhibits a much broader spectrum of biological activities thanvitamin D3 . 1,2 Recently a number of analogues have been found to have specificenhanceme…     

手性溶剂-NMR法测定2,4-滴丙酸对映体纯度的定量分析

研究了手性溶剂法测定2,4-滴丙酸的^1H、^13C谱,在满足NMR准确定量所要求的分离度和信噪比的条件下,能准确测定手性化合物的对映体纯度。比较了以对映体百分含量（R％）和对映体过量（ee）表示手性农药的对映体纯度的差别,发现以对映体百分含量代替对映体过量来表示手性农药的对映体纯度更为准确。     

新型川芎嗪衍生物的合成

以川芎嗪为原料，经氧化、Boekelheide重排、水解和氧化反应合成了中间体3,5,6-三甲基吡嗪-2-甲醛（4）; 4与取代N-4-哌啶酮发生缩合反应合成了9个新型的川芎嗪衍生物，其结构经¹H NMR, ¹³C NMR和MS（ESI）表征。     

24-亚甲基-胆甾烷-3β,5α,6β-三醇的合成

豆甾醇;24-亚甲基-胆甾烷-3β;5α;6β-三醇的合成     

Two New Compounds from Rhododendron Przewalskii Maxim

Two new ionone derivatives, rhododendrone A and rhododendronside, have been isolated from the alco-holic extract of the aerial parts of Rhododendron Przewalskii Maxim. The structures of the two compounds, (3R, 6S)-3-hydroxy-a-ionone 1 and 1,1,5-trimethyl-6-(3-hydroxyl)cyclohexene-5-yl-1-β-D-pyranoglucoside 2, have been elucidated on the basis of the spectroscopic analyses.     

Solvent Effects on the 1H-NMR Chemical Shifts of Imidazolium-Based Ionic Liquids

The ¹H nuclear magnetic resonance (¹H-NMR) spectrum is a useful tool for characterizing the hydrogen bonding (H-bonding) interactions in ionic liquids (ILs). As the main hydrogen bond (H-bond) donor of imidazolium-based ILs, the chemical shift (δ_H2) of the proton in the 2-position of the imidazolium ring (H2) exhibits significant and complex solvents, concentrations and anions dependence. In the present work, based on the dielectric constants (ϵ) and Kamlet-Taft (KT) parameters of solvents, we identified that the δ_H2 are dominated by the solvents polarity and the competitive H-bonding interactions between cations and anions or solvents. Besides, the solvents effects on δ_H2 are understood by the structure of ILs in solvents: 1) In diluted solutions of inoizable solvents, ILs exist as free ions and the cations will form H-bond with solvents, resulting in δ_H2 being independent with anions but positively correlated with β_S. 2) In diluted solutions of non-ionzable solvents, ILs exist as contact ion-pairs (CIPs) and H2 will form H-bond with anions. Since non-ionizable solvents hardly influence the H-bonding interactions between H2 and anions, the δ_H2 are not related to β_S but positively correlated with β_IL.     

Solvent Effects on the NMR Chemical Shifts of Imidazolium-Based Ionic Liquids and Cellulose Therein

The interactions of ionic liquids (IL) with solvents usually used in liquid-state nuclear magnetic resonance (NMR) spectroscopy are studied. The ¹H- and ¹³C-NMR chemical shift values of 1-n-butyl-3-methyl (BM)- and 1-ethyl-3-methyl (EM)-substituted imidazolium (IM) -chlorides (Cl) and -acetates (Ac) are determined before and after diluting with deuterated solvents (DMSO-d₆, D₂O, CD₃OD, and CDCl₃). The dilution offers structural modifications of the IL due to the solvents capacity to ionization. For further investigation of highly viscous cellulose dopes made of imidazolium-based IL, solid-state NMR spectroscopy enables the reproducibility of liquid-state NMR data of pure IL. The correlation of liquid- and solid-state NMR is shown on EMIM-Ac and cellulose/EMIM-Ac dope (10 wt %).     

Investigation of Substituent Effects on Proton and Carbon-13 Chemical Shifts of 4-Substituted Trans-Stilbenes

Proton and carbon-13 chemical shifts of para-substituted stilbenes have been measured. ¹H-¹H, ¹H-¹³C COSY spectra were obtained to analyze unambiguously the chemical shifts of protons and carbons. A long range coupling between 2-H and α-H was observed in a ¹H-¹H COSY spectrum. The observed chemical shifts have been correlated with Hammett substituent parameters. Among ethenyl protons and carbons, all but the chemical shifts of α-H show good correlation with both dual substituent parameters and single substituent parameters. In addition to this finding, the excellent linear correlations of C-l, and 4′-H of 4-substituted trans-stilbenes are also reported. Besides the correlations of chemical shifts with Hammett parameters, a good correlation between the chemical shifts and the calculated charges of position C-4′ are reported.     

Solvent Effect of Dimethyl Sulfoxide on the Chemical Shifts of Phenyl Vinyl Ketones

In our study on the 1D and 2D NMR spectra of synthetic chalcones in DMSO‐d₆, we found that, contrary to our expectation, the signals of α‐carbon correlated to the olefinic protons resonating at lower field whereas the signals of β‐carbon correlated to the olefinic protons resonating at higher field in the spectra of chalcones. To further investigate such solvent effect, four α,β‐unsaturated ketones were prepared and studied separately in CDCl₃ and DMSO‐d₆. The result indicated that the α,β‐unsaturated ketones that possess benzoyl moiety experienced solvent effect in DMSO‐d₆ to result in an anomalous chemical shift. The shift arose from the complexation of solute molecule with DMSO that fixed the steric conformation of solute molecule so that H_β was kept apart from its benzene ring whereas its H_α became more accessible by its benzene ring. Thus, these two olefinic protons would experience a different extent of anisotropic effect exerted by the neighboring benzene ring.     

Solvent and Media Effects on the Photophysics of Naphthoxazole Derivatives

The photophysical properties of 2‐phenyl‐naphtho[1,2‐d][1,3]oxazole, 2(4‐N,N‐dimethylaminophenyl)naphtho[1,2‐d][1,3]oxazole and 2(4‐N,N‐diphenylaminophenyl) naphtho[1,2‐d][1,3]oxazole were studied in a series of solvents. UV–Vis absorption spectra are insensitive to solvent polarity whereas the fluorescence spectra in the same solvent set show an important solvatochromic effect leading to large Stokes shifts. Linear solvation energy relationships were employed to correlate the position of fluorescence spectra maxima with microscopic empirical solvent parameters. This study indicates that important intramolecular charge transfer takes place during the excitation process. In addition, an analysis of the solvatochromic behavior of the UV–Vis absorption and fluorescence spectra in terms of the Lippert–Mataga equation shows a large increase in the excited‐state dipole moment, which is also compatible with the formation of an intramolecular charge‐transfer excited state. We propose both naphthoxazole derivatives as suitable fluorescent probes to determine physicochemical microproperties in several systems and as dyes in dye lasers; consequence of their high fluorescence quantum yields in most solvents, their large molar absorption coefficients, with fluorescence lifetimes in the range 1–3 ns as well as their high photostability.     

溶剂对氟烷基卤代烷^1^9FNMR 化学位移的影响

长期以来,溶剂对反应途径和反应物的影响及他们之间的关系是物理和有机化学家一个十分感兴趣的课题。溶剂影响氟烷基碘的~(19)F NMR 曾有文献报道。我们在研究氟烷基碘与铜反应中的溶剂作用时,发现,在配位能力较小的溶剂中反应经自由基中间体,而在配位能力较大的溶剂中反应是通过氟烷基铜中     

氢甲酰化反应溶剂效应的量子化学研究

在B3LYP/6-31G(d, p)(Rh和P采用LANL2DZ + Polar)水平下,利用自洽反应场（SCRF）的Onsager模型,系统研究了C6H12、C6H6、THF、CH2Cl2、CH3OH和H2O（相对介电常数ε分别为2.02、2.25、7.58、8.93、32.63和78.39）六种溶剂对乙烯氢甲酰化反应中各驻点的结构和反应机理的影响.分别在上述溶剂中优化了反应物、产物、中间体和过渡态的结构,并计算了自由能和活化自由能.计算结果表明,不同溶剂对反应势能面上各驻点的结构和能量均有一定的影响,而且随着相对介电常数ε的增加,反应的活化自由能下降.水是以上六种溶剂中最佳的溶剂,这与大量的实验研究结果一致.     

DCM衍生物双光子吸收截面的溶剂效应

考察了以三苯胺基为给电子基团的4种不同DCM衍生物在有机溶剂中的单光子光物理性质(基态和激发态永久偶极矩差、光学跃迁偶极矩以及跃迁能量等), 并利用双光子诱导荧光法考察了溶剂对其双光子吸收截面(δtpa)的影响. 研究结果表明, DCM衍生物的光学跃迁具有显著的分子内电荷转移特性, 不同末端取代基主要影响其稳态光谱性质, 而分支结构数目主要影响其双光子吸收截面. 研究结果还发现, 双光子吸收截面随分子结构的变化趋势符合双能级模型, 拉电子基团为丙二腈和1,3-茚二酮的DCM衍生物的δtpa随溶剂介电常数的增加呈现不同的变化趋势.