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西洋参皂甙的核磁共振波谱研究Ⅰ.西洋参叶中Ocotillol型皂甙的结构分析 总被引:4,自引:0,他引:4
本文用常规一维1H、13C核磁共振波谱和远程异核化学位移相关谱。异核化学位移相关谱和同核化学位移相关谱技术研究了西洋参叶中首次分离出的一种Ocotillol型皂甙,确认了化学结构,并对其13C、1H NMR谱线进行了归属。 相似文献
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测定了3'(,3")-(二)甲酰基(二)苯并冠醚(1~7)的1H、13C谱,首次结合1H-1H COSY、13C-1H COSY、COLOC二维谱对这些化合物的1H、13C化学位移进行了归属。用NOESY谱确定了合成产物冠4、冠5的结构,并对溶液中的构象异构体及其溶剂影响进行了初探。作者以冠1~8的1H、13C谱的归属为参照,提出了正确归属冠醚醚环上次甲基1H、13C化学位移的一般规则。 相似文献
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报道了一种热转印色带用黄染料的1H、13C NMR , 应用1H NMR、13C NMR、定量碳谱、DEPT、1H-1H COSY、HMQC、HMBC等确定了其在氘代氯仿中的分子结构, 并对全部谱峰进行了归属, 探索了黄染料在氘代氯仿中的结构对13C、1H NMR谱图化学位移及谱峰裂分的影响. 相似文献
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天然结晶辣椒碱的NMR谱研究 总被引:2,自引:0,他引:2
用一维1H NMR谱、1H-1H COSY谱和一维13C NMR谱、DEPT谱研究辣椒碱分子和二氢辣椒碱分子及其混合物,得到1H和13C的化学位移,采用1H NMR谱测定天然辣椒碱中辣椒碱和二氢辣椒碱的相对含量. 相似文献
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用1H-1H COSY,13C-1H COSY,HMBC,NOESY,DEPT以及同核去偶技术,表征了芳香维甲酸乙酯的化学结构,对其1H NMR,13C NMR化学位移进行了指认. 相似文献
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双环磷酸酯类化合物NMR结构效应研究 总被引:7,自引:5,他引:2
用现有理论说明不了双环磷酸酯类化合物31P NMR化学位移的变化。本文在我们提出的核外电子云球对称效应原理基础上,用量子化学和分子力学计算的参数,表达了这类化合物31P化学位移变化的规律,同时还研究了它们的13C NMR化学位移和偶合常数的取代基效应。 相似文献
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B E Hammer 《Magnetic resonance imaging》1989,7(2):235-240
Proton decoupled 13C images were obtained at 2.1 Tesla. 13C[1H] images showed an increase in sensitivity over nondecoupled 13C images because of the nuclear Overhauser effect and elimination of multiple lines from scalar 13C-1H spin-spin couplings. The improvement in S/N for 13C[1H] images was smaller than expected because of a significant decrease in decoupling efficiency when 13C spin echoes were acquired in a readout gradient. Images of 13C compounds that had a wide range of chemical shifts showed separated and/or overlapping images, which is consistent with chemical shift imaging artifacts seen in 1H images. This work examines the technical constraints of acquiring and the difficulties of interpreting 13C[1H] images. 相似文献
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从钩腺大戟中分出的八个阿替烷(Atisane)类型的二萜和一个贝壳杉烷(Kaurane)类型的二萜进行1H-H COSY,13C-1 COSY和1H-1H NOESY测定,使得它们的1H NMR和13C NMR谱的化学位移值得以归属.通过比较这两类二萜的13C NMR谱数据,观察到对于阿替烷类型二萜衍生物中碳20位上的甲基碳的化学位移总在14ppm左右,而贝壳杉烷类二萜,则出现在17ppm左右.这有助于区分现有的这两类二萜的基本骨架. 相似文献
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N. Faska A. Auhmani M. Esseffar J. L‐M. Abboud 《Journal of Physical Organic Chemistry》2011,24(12):1209-1221
Solvent effects on the 1H and 13C NMR chemical shifts of some lactones: β‐propiolactone, γ‐butyrolactone, δ‐valerolactone and ε‐caprolactone, as well as lactams: azetidin‐2‐one, pyrrolidin‐2‐one, δ‐valerolactam and ε‐caprolactam have been investigated and discussed in a wide range of solvents. The experimental results were compared with density functional calculations using a large basis set. Solvent effects were computed by means of an integrated approach including the polarizable continuum model and an optimum number of explicit solvent molecules surrounding the solute. The agreement between computed and experimental chemical shifts fully validates our integrated approach. In order to quantify and elucidate the origin of the solvent effects on the 1H and 13C chemical shifts of the selected compounds, a multi‐linear regression analysis has been carried out using the empirical Kamlet–Abboud–Taft solvatochromic parameters. It has been found that there is a good correlation between the solvent‐induced chemical shifts of 13C and the π* scale of solvent dipolarity polarizability. 1H chemical shifts are affected mainly by the dipolarity–polarizability and the basicity of the solvent. An excellent agreement has been obtained between the calculated and the experimental data. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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研究了5种含有苯环取代基的α,α′—二氧代烯酮环二硫代缩酮类化合物的红外光谱的特征吸收规律,指出了这类化合物分子结构对红外吸收谱带的影响;对^1H NMR,^13C NMR共振谱带做了全面的归属。并且讨论了分子结构对^1H NMR,^13C NMR共振谱带化学位移的影响,其变化规律与红外光谱一致,为这类化合物的结构及谱学研究提供了启发性的模式。 相似文献