C-13 NMR化学シフトの図表化-マスターチャート

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In the investigation of the molecular structure of organic compounds, carbon-13 nuclear magnetic resonance spectrometry is becoming more important in many laboratories. This method can offer directly much information about the skeletal structure of organic compounds. The authors have investigated the tables of chemical shifts for the best utilization of C-13 NMR, and it was concluded that the tables were preferable from a point of view of analytical chemistry if they consisted of a master chart which should be applied to survey roughly the chemical shift ranges of all sorts of organic substances and a series of sub-charts in each of which the shifts of a certain restricted type of compounds were tabulated in detail. In this paper, the authors presented the master chart for the elucidation of 13C-NMR chemical shifts. The chemical shifts of 13C-NMR were greatly influenced by adjacent functions. This influence was usually observed to reach only the second neighbouring carbons with a very few exception. This striking characteristic of 13C-NMR brought an idea that the description of the chemical shifts of α and β carbons with the s carbon may have advantage. It might enable the analysis of the chemical structure near s carbon. The references which were cited for the tabulation of C-13 NMR chemical shifts were listed in table I. Except the data which were ascertained doubtful, nearly 3000 chemical shifts were chosen for the tabulation from the references which were published during the last 11 years. On the data which were not yet published but admitted indispensable for the tabulation, the author's experimental results were applied. Fig. 1 showed general tendency of 13C-NMR chemical shifts. According to Fig. 1, it was observed that sp2 carbons resonated at lower field than sp3 and carbons which followed functions of high electronegativity resonated lower. The chemical shifts of alkanes were in the range of 150 and 185 ppm from CS2, alkene carbons 40 to 90 ppm, and alkyne were at the intermediate range of alkane and alkene. Carbonyl and the centered carbon of allene resonated at the lowest field of all, although there occured a case that when the chemical shifts were removed due to hydrogen bonding, carbonyl carbons resonated in the range of -30 to 35 ppm. An example of application of the master chart was presented.
社団法人日本分析化学会の論文

C-13 NMR化学シフトの図表化-マスターチャート

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