Equilibrium constants for electron-donor–acceptor complexes formed between hexamethylbenzene and 1,3,5-trinitrobenzene in carbon tetrachloride solution determined by 13C nuclear magnetic resonance chemical shifts

1983 ◽  
Vol 79 (11) ◽  
pp. 2729 ◽  
Author(s):  
John A. Chudek ◽  
Roy Foster ◽  
Fiona M. Jarrett
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Carbon Tetrachloride ◽  
Magnetic Resonance ◽  
Electron Donor ◽  
Chemical Shifts ◽  
Equilibrium Constants ◽  
Carbon Tetrachloride Solution ◽  
13C Nuclear Magnetic Resonance ◽  
Donor Acceptor ◽  
Nuclear Magnetic

Semiempirical calculation of 13C nuclear magnetic resonance chemical shifts of acyclic hydrocarbons. Application to the stereochemical analysis of steroidal side chains

1988 ◽  
Vol 66 (1) ◽  
pp. 71-75 ◽  
Author(s):  
Manuel Gonzalez-Sierra ◽  
Daniel A. Bustos ◽  
Edmundo A. Ruveda ◽  
Alejandro C. Olivieri ◽  
Mariano Grasselli
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Side Chains ◽  
Stereochemical Analysis ◽  
Microcomputer Program ◽  
Semiempirical Approach ◽  
13C Nuclear Magnetic Resonance ◽  
Acyclic Hydrocarbons ◽  
Nuclear Magnetic

A semiempirical approach for predicting 13C nuclear magnetic resonance chemical shifts of acyclic hydrocarbons has been adapted to a microcomputer program. A series of methyl and dimethyl substituted cholesterols has been studied using this program, and the predicted shifts are in agreement with literature reports. Preferred conformations of the steroidal side chains have been also predicted and agree with previous studies. A simple rule for analyzing the trends in the chemical shift of the carbon C-20, which is sensitive to changes in the configuration at C-22, is also given, not only for hydrocarbon side chains but also for hydroxy substituted compounds.

Configurationally dependent hydroxyl group effects on 13C nuclear magnetic resonance chemical shifts of olefinic carbons in cyclic six-membered allylic alcohols

1988 ◽  
Vol 66 (12) ◽  
pp. 3128-3131 ◽  
Author(s):  
Teodoro S. Kaufman
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Hydroxyl Group ◽  
Allylic Alcohols ◽  
Stereochemical Assignment ◽  
13C Nuclear Magnetic Resonance ◽  
Group Effects ◽  
Nuclear Magnetic

The differences in chemical shifts of olefinic carbons, Δδ(sp2), of pseudoequatorial and pseudoaxial six-membered allylic alcohols were correlated with the Δδ(sp2) values of their parent olefins. The results obtained reflect configurationally dependent substituent effects, the magnitude of which could be used for the stereochemical assignment of the hydroxyl group in these compounds.

KETO–ENOL TAUTOMERISM IN β-DICARBONYLS STUDIED BY NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY: II. SOLVENT EFFECTS ON PROTON CHEMICAL SHIFTS AND ON EQUILIBRIUM CONSTANTS

1965 ◽  
Vol 43 (5) ◽  
pp. 1516-1526 ◽  
Author(s):  
Max T. Rogers ◽  
Jane L. Burdett
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Chemical Shifts ◽  
Equilibrium Constants ◽  
Tautomeric Equilibrium ◽  
Resonance Spectroscopy ◽  
Proton Chemical Shifts ◽  
Nuclear Magnetic

The effect of various solvents on the proton chemical shifts of a number of acyclic β-di-ketones and β-ketoesters has been observed by nuclear magnetic resonance spectroscopy. These shifts are discussed in terms of the dissociation of intramolecular and intermolecular hydrogen bonds on dilution. A complex of benzene with the enol tautomer of the β-dicarbonyl molecule is proposed. The effect of solvents on the position of the tautomeric equilibrium is discussed.

THE NUCLEAR MAGNETIC RESONANCE SPECTRA OF PARA-SUBSTITUTED PHENOLS

1962 ◽  
Vol 40 (11) ◽  
pp. 2122-2125 ◽  
Author(s):  
W. G. Paterson ◽  
N. R. Tipman
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Carbon Tetrachloride ◽  
Magnetic Resonance ◽  
Infinite Dilution ◽  
Chemical Shifts ◽  
Substituted Phenols ◽  
Linear Relationships ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The nuclear magnetic resonance spectra of a number of para-substituted phenols have been examined. The —OH chemical shifts, extrapolated to infinite dilution in benzene and in carbon tetrachloride, were found to be almost independent of the nature of the ring substituent. Approximately linear relationships were observed between the internal chemical shift of the ring protons and other physical properties.

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