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结合样品核磁测试结果,以具体实例的形式,总结了核磁样品分析的基本要求,分析了核磁管和氘代试剂的选择、样品制备及pH值等因素对核磁测试结果的影响,并提出了样品最优测试条件:核磁管管体内外表面要足够光洁均匀,在高温条件下,优先选用升温核磁管.尽量选择小支封装氘代试剂,降低水峰的影响,并且应考虑样品的性质,避免试剂与测试样品发生反应.样品必须与溶剂充分混合均匀,样品量要在溶液粘度与灵敏度之间做好平衡.在分析与氧、氮和硫共价相连的氢原子时,应该选择恰当的pH溶液.以上研究结果可以为其它样品核磁测试提供借鉴指导. 相似文献
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三乙胺催化的双环氮杂锡氧烷配合物氘代反应研究 总被引:1,自引:0,他引:1
全面研究了三乙胺催化下双环氮杂锡氧烷配合物α 氢的氘代反应 .首先考察了三乙胺催化下双环氮杂锡氧烷配合物α 氢的氘代反应的核磁共振谱 ,研究发现 :在三乙胺存在下 ,有机锡配合物α 氢可以与CD3 OD溶剂发生氘代反应 ,其核磁共振峰强度随着时间而衰减 ,且氘代反应速率与三乙胺的浓度有关 .其次 ,利用核磁共振技术测定氘代反应速率 ,其反应表观速率常数为 2 .0× 1 0 -4 ~ 1 0 .0× 1 0 -4 s-1,推导了其动力学机理并讨论了取代基对氘代反应速率的影响 . 相似文献
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在药物分子中引入甲基可改变其药代动力学特性与药理特性,这种“神奇的甲基效应”使得甲基化成为有机合成与药物化学领域十分重要的一类反应.近年来,过渡金属催化的偶联反应以及光或电促进的有机反应成为甲基化反应的新策略,并相继开发了系列廉价易得、低毒高效、适用性广的甲基化试剂.其中,二甲亚砜(DMSO)作为一种来源广泛、性能优良的溶剂与多功能反应试剂,受到研究者们越来越多的关注.基于此,聚焦交叉偶联反应与自由基反应,系统阐述DMSO/DMSO-d6作为甲基化/三氘甲基化试剂在有机合成中的应用,并探讨相关的反应机理、发展趋势以及合成过程所面临的挑战. 相似文献
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探讨用HP-5毛细管色谱柱,MSD作检测器,以质荷比相对丰度的面积归一方法,定量测定质子泵合成中间体氘代产物的纯度.用此方法测定标准品及氘代苯、氘代蒽结果误差小于2%.实验表明,质荷比相对丰度归一方法简单、快速、灵敏度高,可用于定性、定量监控反应的进行,适用于氘代化合物纯度的测定. 相似文献
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以偶氮二异丁腈(AIBN)为引发剂,首次研究了高转化率下,温度,引发剂用量等对全氘代苯乙烯自由基本体聚合反应的影响。实验发现,较低的反应温度下,氘代单体聚合产物分子量随温度的升高而降低的速率大于非氘代单体;而温度高于90℃时,升高温度对两者分子量的影响均不十分明显。 相似文献
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含氢原子簇化合物H_2Os_3(CO)_(10)与乙炔反应生成顺式加成物[Os_3H(μ,η~2-CH=CH_2)(CO)_(10)]。本文首次报道高含量氘代原子簇D_2Os_3(CO)_(10)与乙炔反应生成合乙烯配位基的氘代原子簇[Os_3D(μ,η~2-CH=CHD)(CO)_(10)],H_2Os_3(CO)_(10)与氘代乙炔反应生成[Os_3H(μ,η~2-CD=CDH)(CO)_(10)],它们在微量亲核试剂吡啶作用下发生μ,η~2-乙烯配位基的顺反异构反应。本文用同位素氘代和~1H,~2H NMR动态波谱联用方法,研究了上述反应和异构化过程,提出了顺反异构化的核磁共振动态波谱证据、反应机理和动力学数据。 相似文献
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氘代苯乙酮d8及其还原产物氘代α苯乙醇d10是合成众多氘标记化合物及全氘代化合物的重要中间体.以氘代苯d6和氘代醋酸d4为原料制得氘代苯乙酮d8,经LiAlD4还原可得氘代α苯乙醇d10[1].其缺点是LiAlD4价格昂贵且不易获得,... 相似文献
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采用核磁共振波谱(NMR)研究了二苯基甲烷二异氰酸酯(MDI)在稀溶液中的水解反应机理.将同一MDI样品分别溶解在氘代氯仿、氘代丙酮和加入少量水分的氘代二甲基亚砜溶剂(DMSO)中,进行核磁共振氢谱(1H NMR)、核磁共振碳谱(13C NMR)测试.结果显示,MDI在含水的DMSO溶剂中测得的谱图与氘代氯仿、氘代丙酮中的差别显著.对该溶液进行了13C-1H异核近程相关(HMQC)、13C-1H异核远程相关(HMBC)及碳原子级数(DEPT 135)测试,并利用经验公式对其进行了详细归属,确认了反应产物的结构.分析得知MDI在含水溶剂中迅速反应,异氰酸酯基转化为脲基和氨基基团.异氰酸酯与水反应生成氨基基团,其与异氰酸酯反应活性比水高,对位取代氨基与水的竞聚率比值为7.1,邻位为1.4,对位取代氨基活性约是邻位的5倍. 相似文献
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Mesylate derivatives of 3-aryl-3-hydroxy-beta-lactams and thiolactams react in DMSO-d(6) by first-order processes to give alcohol products. Substituent effect studies implicate carbocation intermediates (ion-pairs) that are captured by DMSO-d(6) to give transient oxosulfonium ions. Rapid reaction of the oxosulfonium ions with trace amounts of water leads to the alcohol product and regenerates DMSO-d(6). H(2)(17)O labeling studies show that (17)O is incorporated into the DMSO. The mesylate derivatives of endo- and exo-2-hydroxy-2-phenylbicyclo[2.2.1]heptan-3-one also react in DMSO-d(6) to give the alcohol products. Ion-pair intermediates that capture DMSO giving unstable oxosulfonium ions are again proposed. Exo-2-phenyl-endo-bicyclo[2.2.1]heptyl trifluoroacetate readily eliminates trifluoroacetic acid in DMSO-d(6) via a cationic mechanism involving loss of the endo-trifluoroacetate leaving group as well as an exo-hydrogen. The O-methyl oxime derivative of alpha-chloro-alpha,alpha-diphenylacetophenone reacts in DMSO-d(6) to give 1-methoxy-2,3-diphenylindole, a product derived from cyclization of a cationic intermediate. A common ion rate suppression provides further evidence for a cationic mechanism. The triflate derivative of pivaloin reacts by a cationic mechanism in DMSO-d(6) to give rearranged products. The rate is even faster than in highly ionizing solvents such as trifluoroethanol or trifluoroacetic acid. 1-Adamantyl mesylate reacts in DMSO-d(6) by a first-order process (Y(OMs) = -4.00) to give a long-lived oxosulfonium ion, 1-Ad-OS(CD(3))(2)(+), which can be characterized spectroscopically. This oxosulfonium ion reacts only slowly with water at elevated temperatures to give 1-adamantanol. DMSO is therefore a viable solvent for k(s), k(C), and k(Delta) cationic processes. 相似文献
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A new and simple phenylhydrazone-based sensor 1 for acetate has been investigated in DMSO and even in the 95:5 DMSO/H2O (v/v) mixtures. Binding of anions such as AcO-, F- and H2PO4(-) results in a noteworthy change in the visible region of spectrum (approximately 100 nm red shift), which can be detected by the 'naked-eye'. The further insights to the nature of interactions between the sensor 1 and AcO- were investigated by 1H NMR titration experiments in DMSO-d(6). In particular, analytical application and detection of acetate ion have been also studied in the aqueous. 相似文献
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J Fernandez-Bertrán E Reguera P Ortiz 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2001,57(13):2607-2615
The interactions of alkali fluorides with D-xylose have been studied by X-ray diffraction (XRD), infrared spectroscopy (IR), nuclear magnetic resonance (NMR, 1H and 13C) and atomic absorption spectrophotometry. KF and CsF form complexes with D-xylose in a 1:1 molar ratio. These complexes can be obtained by solid state milling the reactants in an agate mortar or from methanolic solutions of the sugar and the salt. LiF and NaF do not form complex with D-xylose. IR and XRD prove the identical nature of the complexes obtained by milling and from solution. IR spectra indicate strong perturbation of the OH stretching vibrations with considerable shifts to lower frequencies, which must be caused by strong hydrogen bond formation to the fluorine anion. The perturbations of C-O bond are weak, indicating that cation binding to the oxygen atoms is not the main interaction responsible for the complex formation. 1H NMR spectra of the D-xylose-KF complex dissolved in deuterium oxide is equal to that of pure D-xylose, indicating the destruction of the complex in solution. The complex is stable in DMSO, and 13C spectra of the complex in DMSO-d6 and in solid state (CPMAS) spectra are in accordance with the observed interactions in the IR spectra. As far as we know, this is the first report of a sugar-halide salt complex in which the anion instead of the cation provides the binding forces. 相似文献
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Bednarek E Sitkowski J Kawecki R Kozerski L Bocian W Pazderski L Priebe W 《Dalton transactions (Cambridge, England : 2003)》2008,(31):4129-4137
Pd(ii) and Pt(ii) chloride complexes with LL = methyl cis-3,4-diamino-2,3,4,6-tetradeoxy-alpha-l-lyxo-hexopyranoside of the formulae [Pd(LL)Cl(2)] and [Pt(LL)Cl(2)], , were studied by (1)H, (2)H, (13)C, (15)N and (195)Pt NMR spectroscopy. These techniques were applied for characterization of the structure and ligand exchange dynamics, in case of diastereomeric species formed from in DMSO-d(6), DMSO-h(6) and H(2)O; their general formula was [Pt(LL)XY](+) (X = Cl, Y = DMSO-d(6), ; X = DMSO-d(6), Y = Cl, ; X = Cl, Y = DMSO-h(6), '; X = DMSO-h(6), Y = Cl, '; X = Cl, Y = H(2)O, ; X = H(2)O, Y = Cl, ). Their theoretical structures and NMR parameters, calculated at the level of DFT approach, were also presented and compared to the experimental data. The model complex [Pt(trans-diaminocyclohexane)Cl(2)], , was studied as well. To the best of our knowledge, this work is the first account dealing with the detailed analysis of structure and dynamics of ligand exchange processes in organic solvents and water, performed for a PtCl(2) complex containing a diaminosugar moiety. The kinetic behavior of the studied coordination compounds suggests that some of them may be potentially active in bioassays against cancer cells. Compound exhibits noticeable versatile ligand exchange possibilities in DMSO and H(2)O. Particularly, it undergoes solvolysis in DMSO-d(6), exchanging one chloride atom and yielding two diastereomers and ; the former, being the kinetically favored species, has the DMSO-d(6) ligand syn to the N(3) atom. The lyophilisate of the respective + mixture, earlier equilibrated in DMSO-d(6), after dissolving in H(2)O yields only the latter isomer, which is thermodynamically favored. The solvolysis of in H(2)O yields instantaneously two diastereomeric monoaquated species, and , amounting to 10% of each. 相似文献
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Kang SO VanderVelde D Powell D Bowman-James K 《Journal of the American Chemical Society》2004,126(39):12272-12273
Multiple deuterium exchange between DMSO-d6 and amide hydrogens in two hexaamido cryptand fluoride receptors has been verified by 19F and 2H NMR and FAB mass spectral studies. Structural results for one of the complexes indicate a tricapped trigonal prism hydrogen bond coordination geometry around an encapsulated fluoride, with hydrogen bonds from fluoride to six amide and three phenyl hydrogens. 相似文献
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[reaction: see text] The fluorescent photoinduced electron transfer (PET) chemosensors 2 and 3 were designed for the recognition of anions possessing two binding sides such as dicarboxylates and pyrophosphate; the anion recognition in DMSO takes place through the two charge neutral thiourea receptor sites with concomitant PET quenching of the anthracene moiety. The anion binding of acetate, phosphate, and pyrophosphate to 2 and 3 was also evaluated by using 1H NMR in DMSO-d6. 相似文献
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Lafitte VG Aliev AE Hailes HC Bala K Golding P 《The Journal of organic chemistry》2005,70(7):2701-2707
[structure: see text] 2-Ureido-4-[1H]-pyrimidinones have been reported to dimerize via quadruple hydrogen bonding systems with dimerization constants >10(6) M(-1) in CDCl3. The dimerization constant, K(dim), is dependent on the solvent as well as the ring-substituents present, where previously alkyl (e.g., R1 = Me) and aromatic moieties (e.g., R1 = p-NO2C6H4, R1 = C6H2(OC13H27)3) have been incorporated at the C-6 position. To assess the influence of alternative, functionalizable, electron-donating groups on the dimerization motif and tautomeric distribution of isomers, the synthesis of compounds possessing aminophenyl functionality at the C-6 position has been achieved. NMR spectroscopy chemical shift analysis revealed that compound 2 (R1 = p-NH2C6H4, R2 = C6H13) existed as the 2-ureido-4-pyrimidinol dimeric DADA array in DMSO-d6, where a dimerization constant of 46 M(-1) was determined. This is the first time that a ureidopyrimidinone quadruple hydrogen bonding DADA array has been observed in pure DMSO, a highly polar solvent. The azo-derivative 5 of compound 2 was prepared which also adopted the pyrimidin-4-ol form in DMSO-d6. Compounds 7, 10 and 11 were then synthesized containing a more hydrophilic PEG unit in the lateral chain and the tautomeric distributions were determined. 相似文献