C-13NMR化学シフトの図表化ハロゲン化合物のサブチャート

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It was observed in many organic compounds that carbon nucleus adjacent to halogen atoms shows an extraordinary C-13 NMR chemical shift, and the authors presented here, the figures for halogen containing compounds, as a link of the researches on the C-13 NMR sub-charts. The independent description of halogenated carbons was found to be convenient because by that, it is possible not only to refrain from complication of all the sub-charts, but also to rule the characteristic of chemical shifts of any kind of halogenated compounds easily. The references cited here are the same as in the previous papers and the number of data is given in parentheses in the figure. Fig. 1 shows the general tendency of C-13 NMR chemical shift of halogen containing compounds. It was found to be clear in whole sorts of compounds that the relation between the chemical shifts and the element contained is, without any exception, in the order of fluorine, chlorine, bromine and iodine from the lower magnetic field. Although the relationship between the functions and their chemical shifts is similar to the corresponding functions containing no halogen atoms, each element is found to show its own characteristic. Carbon adjacent to a fluorine shifts to the lower side than its unsubstituted one, but carbon neighbouring iodine atom shifted to the higher side. In case of carbons attaching chlorine or bromine, the degree of shift is between that of fluorine and iodine as shown in the figure. As an extreme example, Fig. 2 shows the chemical shift of halomethanes. Tetraiodomethane resonates at about 486 ppm from carbon disulfide, and this is the highest chemical shift ever reported. Due to the lack of data and the difficulties of experimental procedures on fluoromethanes, the authors were obliged to presume the chemical shift of polyfluorinated methane derivatives using the data of chloro and fluoroacetic acid and monofluoromethane. The chemical shift of tetrafluoromethane is expected to reach 35ppm, and this is also the lowest value of sp3 carbons. Fig. 3 shows the relation between the number of carbon and the chemical shift of α, β, and γ carbons of 1-halo-n-alkanes. Regardless of chlorine, bromine or iodine derivatives, the α carbons were observed to resonate at the lowest field when the number of carbon is three and this phenomenon is commonly observed with α carbon adjacent to the carbonyl in fatty acids. The chemical shift of α carbon adjacent to chlorine, bromine and iodine is observed to converge nearly 149, 160 and 187ppm respectively when the number of carbon of the alkane is beyond 6.
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C-13NMR化学シフトの図表化ハロゲン化合物のサブチャート

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C-13NMR化学シフトの図表化 ハロゲン化合物のサブチャート

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C-13NMR化学シフトの図表化ハロゲン化合物のサブチャート