13C Nuclear magnetic resonance studies. XII. Conformational effects on 13C shieldings in alicyclic oxygenated compounds

1969 ◽  
Vol 47 (17) ◽  
pp. 3113-3118 ◽  
Author(s):  
G. W. Buchanan ◽  
J. B. Stothers ◽  
Siu-Tzyy Wu
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Similar Data ◽  
Free Energies ◽  
Methyl Substituent ◽  
Decoupling Method ◽  
Magnetic Resonance Studies ◽  
Oxygenated Compounds ◽  
Conformational Effects ◽  
13C Nuclear Magnetic Resonance ◽  
Proton Decoupling

The 13C shieldings of the primary carbinyl carbons in cyclohexylmethanol, its acetate and methyl ether as well as those for the corresponding carbon in their 4-t-butyl derivatives have been measured at 15.1 MHz using the 'proton-decoupling' method. Similar data for the 1-methyl-4-t-butylcyclohexylcarbinols and their acetates were obtained to examine the influence of the additional methyl substituent. Possible origins of the observed conformational effects on 13C nuclear shieldings are considered. The 1H results for the methylene protons in these carbinyl groups are also presented and discussed. These results, which permit estimations of the conformational free energies (−ΔG°) of the —CH2OR groupings (R = H, Ac, Me), are presented to illustrate the 13C approach to conformational analysis.

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.

13C Nuclear magnetic resonance studies. XIV. Conformational effects on carbinyl carbon shieldings in cyclohexanols and derivatives

1969 ◽  
Vol 47 (19) ◽  
pp. 3605-3610 ◽  
Author(s):  
G. W. Buchanan ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Free Energies ◽  
New Approach ◽  
Magnetic Resonance Studies ◽  
Conformational Effects ◽  
Alkyl Derivatives ◽  
Alkyl Groups ◽  
13C Nuclear Magnetic Resonance ◽  
Cis And Trans

The 13C shieldings of the alicyclic carbons bearing oxygen in several cyclohexanols, their acetates and methyl ethers depend on the orientation of the oxygen functions. The compounds examined include the cis- and trans-4-alkyl derivatives in which the alkyl groups are t-butyl,i-propyl, ethyl and methyl, as well as the 3-t-butyl isomers. The results for the parent compounds are employed for the estimation of the conformational free energies of the hydroxyl, acetoxyl, and methoxyl groups, and serve to establish that 13C magnetic resonance (c.m.r.) spectroscopy offers a new approach to conformational analysis. The data were obtained using the decoupling technique and materials containing 13C in natural abundance.

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

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 of Organometallic Compounds. V. Di- and Trimethylplatinum(IV) Derivatives

1974 ◽  
Vol 52 (10) ◽  
pp. 1973-1982 ◽  
Author(s):  
Howard Charles Clark ◽  
Leo Ernest Manzer ◽  
John Edward Henry Ward
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Organometallic Compounds ◽  
Methyl Groups ◽  
Magnetic Resonance Studies ◽  
13C Nuclear Magnetic Resonance ◽  
Cis And Trans ◽  
Nuclear Magnetic

The 13C n.m.r. parameters for thirteen di- and trimethylplatinum(IV) derivatives have been obtained. It is shown that the 13C shieldings and 1JPtC and 2JPtCH values of methyl groups both cis and trans to varied ligands consistently follow trends similar to those found for related methylplatinum(II) derivatives.

Sign in / Sign up

Export Citation Format

Share Document