13C NMR spectra of adamantane derivatives

The carbon-13 chemical shifts of mono- and 1,3-disubstituted adamantanes are reported. The effects caused by the substituents are compared with those met in aliphatic and alicyclic compounds. It is shown that the 1,4-interactions have only minor importance in l-substituted adamantanes. The influence of polar groups on the chemical shifts of γ- and δ-carbon atoms is a typical ‘through-the-bonds’ interaction and correlates with inductive parameters of the substituents.     

Evaluation of limiting-induced shifts of disubstituted adamantane derivatives on the basis of shift additivity

A quantitative interpretation of ¹H NMR spectra of symmetrically disubstituted adamantane derivatives (2,4-adamantanedione, 2,6-adamantanedione and 2,4-adamantanetdiol) with shift reagents is reported. Assumptions are made of shift additivity and an average coordination of one molecule of the shift reagent to both functional groups. A much better fit between the experimental and the calculated set of limiting-induced shifts was obtained for calculations based on shift additivity.     

13C NMR chemical shifts of N-unsubstituted- and N-methyl-pyrazole derivatives

¹³C shielding data for 100 derivatives of pyrazole are reported. These include methyl, ethyl, n-propyl, tert-butyl, phenyl, hydroxymethyl, carboxyl, ethoxycarbonyl, cyano, amino, hydrazino, nitro, azido, chloro, bromo and iodo groups as substituents on the ring carbon atoms.     

Substituent effects on 13C NMR chemical shifts in the saturated framework of primary aliphatic derivatives

A general equation describing the effect of substituents on α-carbons in a saturated framework was developed from ¹³C chemical shifts obtained under uniform conditions for selected aliphatic compounds. Experimental correlations for β- and γ-carbons and a discussion of the results are presented.     

Long range substituent-induced chemical shifts in the 13C NMR spectra of N-benzylidenebenzylamines

Carbon-13 chemical shifts for N-benzylidenebenzylamines are affected by substituents up to eleven bonds away from the substituent group. The data correlate well with Hammett constants.     

13C?13C coupling constants and substituent effects on 13C chemical shifts in 13C labelled pyrene and pyrene derivatives

Long range inter-ring ¹³C? ¹³C couplings are found to be effective in the title compounds, and the magnitudes of coupling constants and of substituent effects on ¹³C chemical shifts, as well as the signs of the latter, alternate with respect to the number of connecting bonds.     

The13C NMR spectra of some polychlorinated dibenzo-p-dioxins. A calculation of13C chemical shifts

The¹³C NMR spectra of a number of polychiorinated dibenzo-p-dioxins (PCDD) were measured. These and previously known spectra were used for the development of a method for calculation of¹³C NMR spectra of chloroaromatics in the framework of a two-particle increment scheme for carbon chemical shifts. The scheme one allows to calculate¹³C chemical shifts for all 75 PCDD.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 760–761, April, 1994.     

丁烷衍生物类木脂素13C NMR化学位移预测

借助原子电性作用矢量(AEIV)和原子杂化状态指数(AHSI),对39种丁烷衍生物类木脂素共计854个等价C原子进行表征,并建立用于模拟该类分子13C NMR化学位移的多元线性回归方程.所得定量结构波谱关系(QSSR)模型及留一法交互检验相关系数分别为r=0.981和q=0.962.进一步用从马尾松松针中分离所得新木脂素中20个13C NMR化学位移对模型进行外部验证,预测结果与实验值较接近.表明所建模型有良好稳定性和泛化力,可对丁烷衍生物类木脂素13C NMR谱学数据准确模拟.     

13C chemical shifts of monosubstituted adamantanes

¹³C chemical shifts are reported for adamantane, nine 1-substituted adamantanes and nine 2-substituted adamantanes. The substituents are F, Cl, Br, I, NH₂, OH, CH², CN and CO₂H. The assignments and results are discussed in terms of chemical shift patterns.     

Quantum-chemical calculations of NMR chemical shifts of organic molecules: XIV. Solvation effects in calculations of chemical shifts in 13C NMR spectra of chlorine-containing compounds

Analysis of precision factors in calculations of ¹³C NMR chemical shifts in the series of saturated and unsaturated organochlorine compounds was performed in the framework of the method of electron density functional theory GIAO-DFT-KT3/pcS-2 in the gas phase and with accounting for solvent effect by the polarized continuum model IEF-PCM. The accounting for solvation effects in calculations of ¹³C NMR chemical shifts within the framework of the IEF-PCM model is not fundamental for organochlorine compounds, yet it considerably improves the precision of calculations up to 2.5 ppm.     

Calculation of chemical shifts in the13C NMR spectra of uncharged molecules and their π-dianions

Physics Institute, Academy of Sciences of the Belorussian SSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 2, pp. 70–76, March–April, 1990.     

13C chemical shifts of phenol derivatives. A correlation with electronic structure

The ¹³C chemical shifts of twenty chloro- and nitro-substituted phenols have been measured in d-chloroform. The influence of substituents on the screening at C-1, on the total charge at this position and on the dipole moments is reported and analysed. The results of this study suggest that variations of the chemical shifts at C-1 for meta-methyl-, meta-chloro-, meta-nitro-, ortho- and para-methyl-, ortho- and para-chlorosubstituents mainly reflect charge density changes. The influence of ortho-nitro groups on the screening of C-1 is more complex.     

Syntheses and 13C NMR spectra of fluorinated adamantane derivatives

The syntheses of a variety of fluorine-containing adamantane derivatives are described. The ¹³C NMR spectra of those compounds with different configurations are interpreted in terms of through-bond and through-space substituent interactions.     

13C NMR spectra of polyiodosubstituted compounds and structural increments in the chemical shifts for carbon in polyiodoalkanes

Conclusions We propose a topological scheme for empirical estimates of ¹³C in polyiodoalkanes containing both individual substituent increments and also structural increments characterizing two-particle steric interactions of substituents, and also including terms taking into account the asymmetry of the total heterograph.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2719–2724, December, 1987.     

Carbon-13 chemical shifts of some propargyl alcohol derivatives

The natural abundance ¹³C chemical shifts of a range of propargyl alcohol derivatives have been determined and individual resonances assigned. The shielding effects of the triple bond and hydroxyl group on neigbouring carbons have been characterised. The observed for these compounds are compared to those of alkyl or allyl alcohols.