Carbon-13 Spectra Research Articles

Nuclear magnetic resonance spectroscopy. Carbon-13 spectra of cholic acids and hydrocarbons included in sodium desoxycholate solutions.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNuclear magnetic resonance spectroscopy. Carbon-13 spectra of cholic acids and hydrocarbons included in sodium desoxycholate solutionsDieter. Leibfritz and John D. RobertsCite this: J. Am. Chem. Soc. 1973, 95, 15, 4996–5003Publication Date (Print):July 1, 1973Publication History Published online1 May 2002Published inissue 1 July 1973https://doi.org/10.1021/ja00796a036RIGHTS & PERMISSIONSArticle Views174Altmetric-Citations94LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (841 KB) Get e-Alerts Get e-Alerts

Carbon-13 nuclear magnetic resonance spectra of lignins

From the 13C-nmr spectra of a large number of dimeric and monomeric lignin model compounds the chemical shifts of the carbon atoms of the C 9-units in lignin with different substitution patterns were determined. The absorption peaks of the carbon-13 spectra of two lignins (beech and spruce) could be assigned by comparison (Table 3).

Carbon-13 Nuclear Magnetic Resonance Spectroscopy of Poly(vinyl acetate) and Poly(vinyl alcohol)

The carbon-13 high resolution nuclear magnetic resonance spectra with proton spin decoupling have been obtained for poly(vinyl acetate) and poly(vinyl alcohol). Carbon-13 resonances of the skeletal carbons of poly (vinyl acetate) are more sensitive to the steric configuration than those of the side-chain carbons. The spectra of α-methine carbons of poly(vinyl alcohol) have clear splits corresponding to triad and (partially) to pentad placements. By comparing the results of carbon-13 spectra with those of proton spectra, it was confirmed that the nuclear Overhauser effect due to the proton decoupling has no influence on the estimation of microtacticity through the relative intensities of peaks in the carbon-13 spectra.It was shown that the detection and estimation of the branches in poly(vinyl alcohol) might be possible by using the carbon-13 resonance.

Nuclear magnetic resonance spectroscopy. Carbon-13 chemical shifts of small peptides as a function of pH.

Carbon-13 spectra of 27 peptides have been obtained by high-resolution nmr spectroscopy with the aid of proton decoupling. The chemical shifts of the different amino acid moieties are found to have systematic deviations from those of the free zwitterionic amino acids. These effects depend very largely on the position of an amino acid in a peptide, i.e., on whether it is a C-terminal, an N-terminal, or a nonterminal unit, but not on the nature of its neighbors in the chain, unless one of these is proline. The results have substantial value for the determination of amino acid sequences in di- and tripeptides. Protonation and deprotonation of zwitterionic peptides have considerable effects on the chemical shifts which are, for the most part, limited to the amino acid units directly involved in the reaction. The one important exception to this rule that we have observed is interpreted as being the consequence of a conformational change which the peptides undergo when transformed from the zwitterion to the anion or cation.

Carbon-13 and nitrogen-15 nuclear magnetic resonance spectroscopy: a fourier N.m.r. study of [15N]quinoline

The carbon-13 and nitrogen-15 magnetic resonance spectra of [15N]quinoline have been measured. A significant nitrogen lone pair effect was observed on the magnitude of 2J[13C(8)–15N] as well as on the carbon chemical shift of C(8).

Nuclear magnetic resonance spectroscopy. Carbon-13 spectra of some common oligosaccharides

The applicability of carbon-1 3 magnetic resonance spectroscopy to the study of oligosaccharides is demonstrated. The spectra of four disaccharides are discussed and interpreted, and the methods used in peak assignments are explained. The dependences of carbon chemical shifts and carbohydrate conformations upon pH are discussed and, contrary to earlier reports, it is shown that no large changes in the anomeric mixture of glucose are observed in strong base. The spectra of four fully acetylated sugars are presented and partially assigned. Finally, a brief investigation of the carbon-13 spectra of amylose and cellulose acetate is presented, and the potential of this method of studying polysaccharide conformations emphasized.

Nuclear magnetic resonance spectroscopy. Carbon-13 spectra of nicotine, quinine, and some Amaryllidaceae alkaloids

The natural-abundance ^(13)C magnetic resonance spectra of nicotine, quinine, several Amaryllidaceae alkaloids, and selected derivatives of these have been determined at 15.8 MHz. With the aid of proton decoupling techniques and the shifts which occur on formation of specific derivatives, it has been possible to make self-consistent and unambiguous assignments of nearly all the resonances for these alkaloids.

Nuclear magnetic resonance spectroscopy. Carbon-13 spectra of some pentose and hexose aldopyranoses

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNuclear magnetic resonance spectroscopy. Carbon-13 spectra of some pentose and hexose aldopyranosesDouglas E. Dorman and John D. RobertsCite this: J. Am. Chem. Soc. 1970, 92, 5, 1355–1361Publication Date (Print):March 1, 1970Publication History Published online1 May 2002Published inissue 1 March 1970https://doi.org/10.1021/ja00708a041RIGHTS & PERMISSIONSArticle Views350Altmetric-Citations223LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (751 KB) Get e-Alerts Get e-Alerts

Nuclear magnetic resonance spectroscopy. Carbon-13 spectra of some inositols and their O-methylated derivatives

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNuclear magnetic resonance spectroscopy. Carbon-13 spectra of some inositols and their O-methylated derivativesDouglas E. Dorman, S. J. Angyal, and John D. RobertsCite this: J. Am. Chem. Soc. 1970, 92, 5, 1351–1354Publication Date (Print):March 1, 1970Publication History Published online1 May 2002Published inissue 1 March 1970https://doi.org/10.1021/ja00708a040RIGHTS & PERMISSIONSArticle Views203Altmetric-Citations96LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (453 KB) Get e-Alerts Get e-Alerts

Nuclear magnetic resonance spectroscopy. Carbon-13 spectra of the silver(I) complexes of cyclopentene and cyclohexene

In recent years, proton magnetic resonance spectroscopy has been utilized to investigate the nature of the species arising when alkenes are dissolved in solutions containing either silver(I) or mercury(II) ions. We report here on the use of high-resolution nmr spectra of ^(13)C (cmr) in natural abundance in examining such complexes.

Nuclear magnetic resonance spectroscopy. Carbon-13 spectra of steroids

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNuclear magnetic resonance spectroscopy. Carbon-13 spectra of steroidsHans J. Reich, Manfred Jautelat, Mark T. Messe, Frank J. Weigert, and John D. RobertsCite this: J. Am. Chem. Soc. 1969, 91, 26, 7445–7454Publication Date (Print):December 1, 1969Publication History Published online1 May 2002Published inissue 1 December 1969https://doi.org/10.1021/ja01054a037RIGHTS & PERMISSIONSArticle Views503Altmetric-Citations294LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (903 KB) Get e-Alerts Get e-Alerts

Studies of 13C 13C coupling constants. II. Acetonitrile and related compounds

Carbon-13 spectra were obtained on a series of alkyl nitriles and the acylium ion, CH 3CO +. Results are given on carbon-carbon and carbon-proton coupling constants for the series methyl-, ethyl-, isopropyl-, and t-butyl-cyanides as well as the acylium ion. CNDO molecular orbital calculations were carried out as aid in application of the Pople-Santry approach to spin coupling and in application of the localized model of the CC bond. The correct trend in CC coupling, although opposite to that predicted from the simple P SA SB bond-order, is rationalized for CH 3CN and CH,CO +.

Nuclear magnetic resonance spectroscopy. Carbon-13 spectra of aliphatic carboxylic acids and carboxylate anions

The ^(13)C chemical shifts of each of the carbons of the simple aliphatic carboxylic acids and their corresponding anions from formic to valeric acid have been measured in aqueous solution. Perhaps surprisingly, ionization of an aliphatic acid results in a downfield shift of its carbon resonances. The results have been correlated with other substituent effects, with ^(13)C and H resonances in corresponding hydrocarbons, and with the distance between the carboxylic(ate) group and the carbons undergoing resonance absorption.

Studies of 13C 13C coupling constants. I. Acetyl compounds ( 1, 2)

Carbon-13 spectra were obtained on a series of synthetically di- or monolabelled acetyl compounds, CH 3COX. Results are given on J CC and J CH for compounds with X = H, CH 3, I, ONa (aq), N(CH 3) 2, Br, Cl, OH and OC 2H 5. The range of values of J CC is 39.4–58.8 in this series, much larger than can be accounted for in terms of arguments based on changes in the effective nuclear charge or on hybridization arguments. An interpretation in terms of the Pople-Santry theory, based on a localized model of the CC bond, is presented.

Carbon-13 and proton magnetic resonance spectra of D-glucose- 13C

Carbon-13 and proton magnetic resonance spectra of D-glucose- 13C

Nuclear magnetic resonance spectroscopy. Carbon-13 spectra of five-membered aromatic heterocycles

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNuclear magnetic resonance spectroscopy. Carbon-13 spectra of five-membered aromatic heterocyclesFrank J. Weigert and John D. RobertsCite this: J. Am. Chem. Soc. 1968, 90, 13, 3543–3549Publication Date (Print):June 1, 1968Publication History Published online1 May 2002Published inissue 1 June 1968https://doi.org/10.1021/ja01015a045RIGHTS & PERMISSIONSArticle Views275Altmetric-Citations121LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (787 KB) Get e-Alerts Get e-Alerts

On the new chemical nomenclature

This paper reports a study of a polymer sequence, and the striking changes with stereochemical configuration in polymethyl methacrylate (PMMA) by radiation-induced polymerization. The polymer structure was investigated by means of 13C NMR spectroscopy, showing that carbon-13 spectra were interpreted in terms of pentad sequences for the CO resonance; the spectrum reveals seven separate resonance lines, which can be assigned to the ten possible pentads. Comparison of the observed and calculated intensities of the assigned resonances indicated that the Bernoullian statistic describes the radiation-induced polymerization mechanism of the PMMA sample under study. The experimental results show the radiation induced dose and the probabilities of isotactic, syndiotactic and heterotactic triads are a function of Pm, respectively. The preference of the propagation or degradation for the syndiotactic in PMMA can be found due to the activation enthalpy and dependence of radiation dose. The difference in the free activation enthalpies is from 923 cal/mol to 773 cal/mol with higher activation entropy in the growth step. Molecular weights of PMMA by various radiation dose in polymerization were determined by GPC. The authors have estimated the N-ads distinction equation, and by using this distinction equation satisfactory results have been obtained. The Bernoullian process can then be distinguished.