13C NMR spectroscopic study of epoxidized 1,4-polyisoprene and 1,4-polybutadiene

Partly epoxidized cis- and trans-1,4-polyisoprenes and cis-and trans-1,4-polybutadienes were prepared, and their ¹³C NMR spectra examined. All the prominent resonances in the spectra of the epoxidized polymers were assigned by using lanthanide shift reagent and off-resonance decoupling experiments. A ¹³C NMR method of quantitative assessment of the epoxide content was developed following determination of relative spin-lattice relaxation time (T₁) and nuclear Overhauser effect (NOE) parameters of the various carbons in the epoxidized polyisoprenes and polybutadienes.     

Synthesis of organophosphorus derivatives of lupinine and epilupinine and their interaction with cholinesterases

Conclusions Some esters of O-alkyl methylphosphonic acid and thioesters of O-alkyl methylthiophosphonic acid derived from the alkaloids lupinine and epilupinine have been prepared. These were found to be reversible competitive inhibitors of acetylcholinesterase and butyrylcholinesterase.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 650–654, March, 1987.     

13C NMR spectroscopic data for glutinol and derivatives

The ¹³C NMR chemical shifts of the triterpenes glutinol, glutinone and acetylglutinol were measured and analysed.     

13C NMR spectra of azolopyridines and their quaternary salts

¹³ C NMR spectra of some azole series have been investigated: 2-pyridylbenzimidazoles, 2-pyridylimidazo [4,5-b]-pyridines, 2-pyridylimidazo[4,5-c]-pyridines, analogous oxazole compounds, as well as their mono- and bisquaternary salts. Some problems, related to the structure of these compounds in solution, have been discussed.V. I. Vernadskii Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow 117975. Torino University, Italy. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 866–872, April, 1992.     

13C NMR and ESR spectroscopic investigations on tert-butyl-substituted cyclopentadienones

¹³C NMR spectra of 11 di-, tri- and tetra-tert-butyl-substituted cyclopentadienones are discussed with respect to charge distribution and substituent effects. The chemical shifts of the unsubstituted cyclopentadienone, calculated from substituent increments, are in good agreement with published CNDO calculations and can be rationalized by the inductive effect of the carbonyl group. In addition, the ESR signals shown by some of the cyclopentadienones are described, and possible reasons for their appearance are discussed.     

13C and 1H NMR spectral studies of N-alkylmethylquinolinium salts

¹³C and ¹H chemical shifts of fourteen N-alkylmethylquinolinium salts in DMSO-d₆ are reported, and compared with those of the eleven corresponding methylquinoline bases. The influence of ring substitution by methyl groups in the salts and substitution at the nitrogen atom and the effect of the anion are discussed.     

X-ray structural and13C NMR spectroscopic investigation of 4,7-diaminocoumarins

An x-ray structural study has been made of 7-diethylaminocoumarin and 4-morpholino-7-diethylaminocoumarin. A study has been made of the¹³C NMR spectra of these compounds and other 4,7-diaminocoumarins, in CDCl₃, and in acidic media. These studies have established that the site of first protonation is the nitrogen atom in position 7, and the site of the second protonation is the lactone oxygen atom. It is concluded that the 4-amino group is effectively conjugated with the carbonyl group in 4,7-diaminocoumarins.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 802–810, April, 1991.     

Saturated amine oxides: Part 5. Hydroacridines: Part 24. 13C NMR chemical shifts of N‐epimeric saturated six‐membered azaheterocyclic amine oxides

The ¹³C NMR spectra of 22 piperidine‐, tropine‐ and tetradecahydroacridine‐derived saturated amine oxides were measured. The chemical shifts were assigned on the basis of APT and 2D‐INADEQUATE spectra, and are briefly discussed. Copyright © 2003 John Wiley & Sons, Ltd.     

A carbon-13 NMR spectroscopic study of ferrocenylmethyl carbonium ions

The ¹³C NMR spectra of three ferrocenylmethyl carbonium ions and of the alcohols from which they were derived have been obtained. The chemical shifts and coupling constants of the carbonium ions are explicable in terms of a structure that has the positive charge extensively delocalized throughout the entire molecule, with a fulvenelike structure for the substituted cyclopentadienyl ring.     

1H, 13C and 15N NMR study of vinyltetrazolium salts and processes of their synthesis

The ¹H, ¹³C and ¹⁵N NMR spectra of several N- and C-vinyltetrazolium salts have been recorded and the observed chemical shifts together with the data of quantum-chemical calculations have been used for evaluation of electronic structure of the investigated substances and selectivity of the exhaustive alkylation of 1,5- and 2,5-substituted tetrazoles.     

NMR and IR spectroscopic study of the structure of quaternary salts of 1-vinylpyrazoles

Conclusions IR and NMR spectral analysis indicated that quaternization of 1-vinylpyrazoles leads to a decrease in conjugation between the heterocycle and the vinyl group and to a significant leveling out of the charges on the atoms in the heterocycle and vinyl group.DeceasedTranslated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1007–1012, May, 1985.     

Studies in tertiary amine oxides. III—carbon-13 NMR assignment of N-alkynyl cyclic amines

Carbon-13 NMR spectra of 24 N-alkynyl cyclic amines were analysed. The effect of substituting the acetylenic proton by n-butyl, tert-butyl and phenyl groups was determined.     

N-Oxides of polychloropyridines.13C NMR study

The effect ofN-oxidation of a series of polychloropyridines on¹³C NMR parameters has been studied. It has been established that inN-oxides of polychloropyridines an electric field through-space effect of theN-oxide group predominates in the shielding of the -carbon atom compared to the other carbon atoms. A linear correlation between¹³C NMR chemical shifts and total charge densities calculated by the MNDO method for the carbon atoms ofN-oxides of polychloropyridines has been found.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2425–2428, December, 1995.The authors are grateful to V. V. Kolchanov for help in the synthesis of compounds under study.     

[13C]NMR study of naphthoflavones

The [¹³C]NMR spectra of α-,β- and γ-naphthoflavones were assigned at 25.2 MHz resorting to models such as the unsubstituted flavone and appropriate substituted acetylmethoxynapthalenes. Supporting evidence for the assignments was provided by gated decoupled spectra and all the chemical shifts in the 11 compounds studied gave a self-consistent data set.     

13C NMR spectral study of polyacetoxyxanthones. IV—13C NMR spectroscopy of substituted xanthones

The ¹³C NMR chemical shifts of nine acetoxyxanthones are reported and identified. The acetoxy substituent effects have been evaluated and the corresponding shift increments proposed.     

13 C NMR spectroscopy of substituted xanthones—II: 13C NMR spectral study of polyhydroxy xanthones

The ¹³C NMR chemical shifts of eleven hydroxy-, two hydroxymethoxy xanthones, and xanthone-C-glucoside, mangiferin, are presented and analyzed. Hydroxy substituent effects depending on substituent position as well as on shielded ring carbon position have been evaluated. Hydroxy substituent increments for xanthones are proposed. Effects of hydroxylation on carbonyl carbon shift and the methylation of hydroxy group and the corresponding shift increments which are of diagnostic value have been observed and discussed.     

A 13C NMR spectroscopic study of the phase transitions of alkane dicarboxylic acids in the solid state

¹³C NMR spectra of a few odd-member alkane dicarboxylic acids such as glutaric and pimelic acids have been studied across their phase transitions. The spectra provide clear evidence for the structural changes accompanying the transitions. In the case of malonic acid, the study establishes that the two carboxyl units are equivalent in the high-temperature phase unlike in the other odd-member dicarboxylic acids where they are non-equivalent.     

NMR spectroscopic and X-ray crystallographic study of methylcobalt(III) compounds with saturated amine ligands

The (13)C chemical shifts of methylcobalt(III) compounds with saturated amine ligands in cis positions to the methyl group and a monodentate ligand, L = CN(-), NH(3), NO(2)(-), N(3)(-), H(2)O, or OH(-), in the trans position are reported. The amine ligands used, 1,2-ethanediamine (en), 1,3-propanediamine (tn), N,N'-bis(2-aminoethyl)-1,3-propanediamine (2,3,2-tet), N,N'-bis(3-aminopropyl)-1,2-ethanediamine (3,2,3-tet), and 1,4,8,11-tetraazacyclotetradecane (cyclam), all exert an apparent cis influence on the (13)C resonance signal of the coordinated methyl group. In the trans-[Co(en)(2)(CH(3))(L)](n+) series the (15)N resonance frequency of the coordinated en has also been measured. The influence of L on the en (15)N chemical shifts is reverse the influence on the methyl (13)C chemical shifts except in the case of L = NO(2)(-), which affects a further deshielding of the amine nitrogen nucleus. The methyl (1)J(CH) coupling constants in the trans-[Co(en)(2)(CH(3))(L)](n+) series range from 128.09 Hz (L = CN(-)) to 134.11 Hz (L = H(2)O). The crystal structures of trans-[Co(en)(2)(CH(3))(ClZnCl(3))], trans-[Co(3,2,3-tet)(CH(3))(N(3))]ClO(4), trans,trans-[(CH(3))(en)(2)Co(CN)Co(en)(2)(CH(3))](PF(6))(3)(CH(3)CN), and cis-[Co(en)(2)(CH(3))(NH(3))]ZnCl(4) were determined from low-temperature X-ray diffraction data.     

Solution cation‐binding properties of segmented polyethylene oxide–A 13C NMR spectroscopic study

Two segmented polyethylene oxides, SPEO‐3 and SPEO‐4, were prepared using a novel transetherification methodology. Their structures were confirmed by ¹H and ¹³C NMR spectroscopy. The complexation of these SPEO's with alkali–metal ions in solution was investigated by ¹³C NMR spectroscopy. The mole‐fraction method was used to determine the complexation ratio of SPEO with LiClO₄ at 25 °C, which showed that these formed 1:1 (polymer repeat unit/salt) complexes. The association constant, K, for the complex formation was calculated from the variation of the chemical shift values with salt concentration, using a standard nonlinear least‐square fitting procedure. The maximum change in chemical shift (Δδ) and the K values suggest that both SPEO‐3 and SPEO‐4 formed stronger complexes with lithium salts than with sodium salts. Unexpectedly, the K values were found to be different, when the variation of δ of different carbons was used in the fitting procedure. This suggests that several possible complexed species may be in equilibrium with the uncomplexed one. Structurally similar model compounds were also prepared and their complexation studies indicated that all of them also formed 1:1 complexes with Li salts. Interestingly, it was observed that the polymers gave higher K values suggesting the formation of more stable complexes in polymers when compared to the model analogues. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2635–2644, 2000     

13C NMR spectroscopic study of scandium dimetallofullerene, Sc2@C84 vs. Sc2C2@C82

Although Sc2C84 has been widely believed to have the form Sc2@C84, the present 13C NMR study reveals that it is a scandium carbide metallofullerene, Sc2C2@C82, which has a C82(C(3v)) cage.