C-13NMR化学シフトの図表化-カルボニル化合物のサブチャート

概要

論文の詳細を見る
In our previous paper, a master chart of C-13 NMR chemical shifts for the organic compounds was given, which could be used for the survey of the chemical shifts of all sorts of organic substances. Along this line, it is aimed in this paper to present the results of a study for graphic representation of the C-13 NMR chemical shifts of carbonyl compounds. A sub-chart of the chemical shifts for carbonyl, αand β-carbons is presented surveying about 450 compounds (Fig. 1). The chemical shifts of carbonyl carbon appeared in a total range of ca. 80 ppm at the low-field end of the C-13 spectral region. When the resonance in CS2 is taken as the origin of the chemical shift scale, the chemical shifts for carbonyl carbons in esters lie in the range, 16 to 33 ppm, in carboxylic acids, 9 to 30 ppm, in aldehydes, -10 to + 10 ppm and in ketones, -30 to 0 ppm. The chemical shifts for carbonyl carbon in nucleosides appear in the range, 34 to 45 ppm, in amides, 18 to 37 ppm, acid halides, 22 to 35 ppm, in halogenated carboxylic acids, 20 to 32 ppm, in halogenated ketones, -7 to + 20 ppm and in metal carbonyls, -35 to 0 ppm. The resonances for the carbonyl carbon in various halogenated carbonyl compounds shifted largely towards the higher field, which probably could be attributed to the heavy atom effect. In unsaturated carbonyl compounds, the resonances of the β-carbons are shifted to the lower field than those of the α-carbons, while the reverse is true for the saturated compounds. A remarkable fact is found for the chemical shift of α-carbon of saturated carboxylic acid (Table I). That is, a low-field shift of 78ppm per carbon is observed with increase of numbers of carbons until to butyric acid whose value is found to be a minimum (156. 5 ppm). The shift is, however, no longer observed for the compounds which have five or more carbons, and the values of the chemical shifts converge to a constant value, i.e., 159 ppm. Similar tendency of low-field shift and convergency of the chemical shift are also observed for β-carbon.
社団法人日本分析化学会の論文

C-13NMR化学シフトの図表化-カルボニル化合物のサブチャート

スポンサーリンク

概要

著者

関連論文

スポンサーリンク