17O NMR study of substituent effects in 4-substituted N-chlorobenzamides and comparison with 4-substituted benzamides: sensitivity to ring substituents (ρ) reflects electronic and steric effects

1997 ◽  
pp. 1547-1550 ◽  
Author(s):  
Michael De Rosa ◽  
David W. Boykin ◽  
Alfons L. Baumstark
Keyword(s):  
Substituent Effects ◽  
Steric Effects ◽  
17O Nmr ◽  
Nmr Study ◽  
Substituted Benzamides ◽  
Electronic And Steric Effects

Electronic and steric effects on the three-fold Scholl-type cycloheptatriene ring formation around a tribenzotriquinacene core

2017 ◽  
Vol 4 (5) ◽  
pp. 817-822 ◽  
Author(s):  
Ho-Wang Ip ◽  
Hak-Fun Chow ◽  
Dietmar Kuck
Keyword(s):  
Substituent Effects ◽  
Ring Formation ◽  
Steric Effects ◽  
Electronic And Steric Effects

Single and triple bay-bridging Scholl-type cyclizations of several 1,4,8-triaryl-substituted tribenzotriquinacenes are subject to pronounced electronic and steric substituent effects.

Ortho Effect in Dissociation of Substituted N-Phenylbenzenesulfonamides

2001 ◽  
Vol 66 (9) ◽  
pp. 1380-1392 ◽  
Author(s):  
Jiří Nádvorník ◽  
Miroslav Ludwig
Keyword(s):  
Experimental Data ◽  
Latent Variables ◽  
Dissociation Constants ◽  
Substituent Effects ◽  
Principal Component ◽  
Steric Effects ◽  
Deviation Analysis ◽  
Acid Base Equilibrium ◽  
The Difference ◽  
Electronic And Steric Effects

Twenty-five 2,2'-disubstituted N-phenylbenzenesulfonamides (2-X-C6H4SO2NHC6H4-Y-2') were synthesised and their purity checked by elemental analysis. This set of model substrates involved all possible combinations of methoxy, methyl, hydrogen, chloro, and nitro substituents. The dissociation constants of the sulfonamides were determined by potentiometric titration in methanol, pyridine, dimethyl sulfoxide, N,N-dimethylformamide, acetone, and acetonitrile. The dissociation constants pKHA obtained were correlated with various sets of substituent constants describing electronic and steric effects of the substituents, and the statistically treated data were used to discuss the contribution of the substituent effects in the dissociation and the difference between the effects transmitted from the two rings. A linear regression model explaining 99% of the variability of experimental data in all the solvents has been found and discussed. Moreover, the experimental data were also interpreted by the methods using latent variables, the principal component analysis (PCA) and conjugated deviation analysis (CDA), and two latent variables were shown to be statistically significant in the description of dissociation. The first obviously describes common action of electronic and steric effects of substituents; the other probably concerns a combined effect of substituent and solvent on the position of acid-base equilibrium.

Oxygen-17 NMR study of electronic and steric effects in furan-2,3-dione derivatives

1992 ◽  
Vol 30 (9) ◽  
pp. 837-840 ◽  
Author(s):  
M. Hnach ◽  
H. Zineddine ◽  
R. Faure ◽  
J. P. Aycard
Keyword(s):  
Steric Effects ◽  
Nmr Study ◽  
Electronic And Steric Effects

17O NMR study of ortho and alkyl substituent effects in substituted phenyl and alkyl esters of benzoic acids

2011 ◽  
Vol 76 (12) ◽  
pp. 1737-1763 ◽  
Author(s):  
Vilve Nummert ◽  
Vahur Mäemets ◽  
Mare Piirsalu ◽  
Signe Vahur ◽  
Ilmar A. Koppel
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
Alkyl Substituent ◽  
Ester Group ◽  
Carbonyl Oxygen ◽  
Steric Interaction ◽  
Alkyl Esters ◽  
17O Nmr ◽  
Nmr Study ◽  
Substituent Constants

17O NMR spectra for 44 ortho-, meta- and para-substituted phenyl and alkyl benzoates (C6H5CO2C6H4-X, C6H5CO2R) at natural abundance in acetonitrile were recorded. Substituent effects on the 17O NMR chemical shifts, δ(17O), of the carbonyl oxygen and the single-bonded phenoxy (OPh) and alkoxy (OR) oxygens have been studied. The δ(17O) values of the carbonyl oxygen for para derivatives showed a good correlation with the σ° constants. The δ(17O) values of carbonyl oxygen for ortho derivatives were found to be described well with the Charton equation containing the inductive, σI, resonance, σ°R, and steric, EsB, substituent constants in case the data treatment was performed separately for electron-donating +R and electron-attracting –R substituents. The electron-donating +R ortho and para substituents in substituted benzoates caused shielding and the electron-withdrawing –R substituents produced deshielding of the O signal. The steric interaction of ortho substituents with the ester group decreased the electron density at the carbonyl oxygen. In alkyl benzoates the δ(17O) values were found to be described well with the inductive, σI, and the steric, EsB, substituent constants.

Electronic and steric effects on the intramolecular Schmidt reaction of alkyl azides with secondary benzyl alcohols

Tetrahedron ◽  
2014 ◽  
Vol 70 (3) ◽  
pp. 643-649 ◽  
Author(s):  
Xiaowei Sun ◽  
Chengzhe Gao ◽  
Fan Zhang ◽  
Zhuang Song ◽  
Lingyi Kong ◽  
...  
Keyword(s):  
Steric Effects ◽  
Schmidt Reaction ◽  
Benzyl Alcohols ◽  
Alkyl Azides ◽  
Electronic And Steric Effects
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