13C Nuclear Magnetic Resonance Studies. XVI. 13C Spectra of some Substituted Acrylic Acids and their Methyl Esters. A Correlation of Olefinic Shieldings in α,β-unsaturated Carbonyl Systems

1972 ◽  
Vol 50 (5) ◽  
pp. 601-611 ◽  
Author(s):  
H. Brouwer ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Regression Analysis ◽  
Methyl Esters ◽  
Linear Regression Analysis ◽  
Magnetic Resonance Studies ◽  
Carbonyl Derivatives ◽  
Solvent Dependence ◽  
13C Nuclear Magnetic Resonance ◽  
Unsaturated Carboxylic Acids ◽  
Acrylic Acids

The carbon-13 n.m.r. spectra of 26 α,β-unsaturated methyl esters and 16 substituted acrylic acids have been determined and the 13C shieldings are discussed. These data are compared with the recently reported values for several α,β-unsaturated carboxylic acids. Linear regression analysis of the olefinic shielding data for several α,β-unsaturated carbonyl derivatives yields a set of parameters which correlate the results with reasonable precision. The solvent dependence of the 13C shieldings of acrylic acid and methyl acrylate has been examined briefly. The proton results for the methyl esters are discussed briefly.

13C Nuclear Magnetic Resonance Studies. 29. 13C Spectra of Some Alicyclic Methyl Esters

1973 ◽  
Vol 51 (13) ◽  
pp. 2092-2097 ◽  
Author(s):  
M. Gordon ◽  
S. H. Grover ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Carboxylic Acid ◽  
Magnetic Resonance ◽  
Methyl Esters ◽  
Membered Ring ◽  
Model Compounds ◽  
Magnetic Resonance Studies ◽  
13C Nuclear Magnetic Resonance ◽  
Acid Esters ◽  
Shielding Effects

The shielding effects of the carbomethoxyl group on neighboring carbons in the cyclohexane and trans-decalin ring systems have been characterized by 13C n.m.r. examination often model compounds. The data show that sufficient differences are exhibited by axial and equatorial groups to permit stereochemical assignments in related systems. The observed trends are compared with those produced by other functional groups. The three-, four-, and five-membered ring cycloalkae carboxylic acid esters were also examined.

13C Nuclear Magnetic Resonance Studies of Methylated Anthracenes

1975 ◽  
Vol 53 (13) ◽  
pp. 1958-1969 ◽  
Author(s):  
Myron L. Caspar ◽  
J. B. Stothers ◽  
Nancy K. Wilson
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Regression Analysis ◽  
Standard Deviation ◽  
Magnetic Resonance ◽  
Substituent Effects ◽  
Methyl Substituent ◽  
Magnetic Resonance Studies ◽  
Charge Densities ◽  
13C Nuclear Magnetic Resonance ◽  
Proton Decoupling

The 13C n.m.r. spectra of anthracene and 11 methylated anthracenes have been examined. Analysis of the 1H spectra allowed unequivocal assignments for most of the protonated carbons by selective proton decoupling. Parameters describing the methyl substituent effects on the aryl carbon shieldings were defined and refined by regression analysis so that the 13C shieldings were predicted for 67 independent aryl positions in anthracenes without peri-methyls with a standard deviation of 0.12 p.p.m. Peri methyl-methyl interactions cause considerable deviations from the predicted substituent effects. The relationships of the 13C shieldings to charge densities calculated by the CNDO/2 method were briefly examined. Syntheses of 2,7,9-trimethyl-, 1,4,5,8- and 1,4,5,9-tetramethyl-, and 1,4,5,8,9-pentamethylanthracene are described.

X-Ray crystallographic and 13C nuclear magnetic resonance studies of 3,4,5,6-tetrahydro-2H-1,3,4-oxadiazin-2-ones derived from ephedrine and pseudoephedrine

Tetrahedron ◽  
2001 ◽  
Vol 57 (49) ◽  
pp. 9789-9798 ◽  
Author(s):  
Shawn R Hitchcock ◽  
George P Nora ◽  
David M Casper ◽  
Michael D Squire ◽  
Christopher D Maroules ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Studies ◽  
X Ray ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic
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