Orthoeffect and steric inhibition of resonance: basicities of methyl-substituted acetophenones

2003 ◽  
Vol 16 (10) ◽  
pp. 721-725 ◽  
Author(s):  
Eva Otyepková ◽  
Tat'jana Nevěčná ◽  
Jiří Kulhánek ◽  
Otto Exner
Keyword(s):  
Steric Inhibition Of Resonance

Estimate of Hyperconjugation Strength in Alkylaromatics and Unsaturated Hydrocarbons Derived from Refractometric Data

2020 ◽  
Vol 23 (23) ◽  
pp. 2598-2613
Author(s):  
Boris A. Zaitsev
Keyword(s):  
Quantitative Estimation ◽  
Physical Phenomenon ◽  
Unsaturated Hydrocarbons ◽  
Resonance Effects ◽  
Alkyl Derivatives ◽  
Retrospective View ◽  
Scientific Papers ◽  
Polycyclic Aromatic ◽  
Qualitative Measure ◽  
Steric Inhibition Of Resonance

: A retrospective view of exaltation of refraction observed for many unsaturated and aromatic compounds demonstrates that this physical phenomenon is undeservedly considered only as a qualitative measure of conjugation. This mini-review discusses numerous papers by the author that have been published earlier in inaccessible periodicals and collections of scientific papers. Using a great number of illustrations, the author shows that this parameter can be successfully used for quantitative estimate of resonance effects in organic and polymer chemistry. The methods for derivation of strictly additive atomic and group refraction constants are described; these constants were subsequently used as a tool that allowed quantitative estimation of resonance effects in mono-, di-, tri- and polyalkylbenzenes, alkylnaphthalenes, some alkyl derivatives of unsaturated hydrocarbons. These effects cause strictly fixed increase in refraction of carbon atoms in different structural modifications (graphene, fullerene, diamond) and in polycyclic aromatic hydrocarbons. The relevant results regarding quantitative estimation of degree of steric inhibition of resonance in sterically hindered ortho-dialkylbenzenes, 1,2,3- trialkyl-, 1,2,3,4-tetraalkyl-, and 1,2,3,4,5-polyalkylbenzenes accumulated by the author are summarized.

The Dinitration of Dimethylacetanilides

2003 ◽  
Vol 2003 (5) ◽  
pp. 303-304 ◽  
Author(s):  
Inmaculada C. Rodriguez Medina ◽  
James R. Hanson
Keyword(s):  
Methyl Group ◽  
H Nmr ◽  
Nmr Methods ◽  
Steric Inhibition Of Resonance

The orientation of dinitration of the dimethylacetanilides has been examined by 1H NMR methods and a possible enhancement of the hyperconjugative influence of a methyl group has been considered as an additional factor augmenting the effect of the steric inhibition of resonance on the orientation of substitution.

THE ULTRAVIOLET ABSORPTION SPECTRA OF SOME CARBOXY DERIVATIVES OF NAPHTHALENE

1949 ◽  
Vol 27b (5) ◽  
pp. 437-461 ◽  
Author(s):  
Y. Hirshberg ◽  
R. Norman Jones
Keyword(s):  
Dicarboxylic Acid ◽  
Absorption Spectra ◽  
General Problem ◽  
Acid Anhydride ◽  
Ultraviolet Absorption ◽  
Dioxane Solution ◽  
Ethanolic Solution ◽  
Complex Molecules ◽  
Steric Inhibition Of Resonance ◽  
Derivatives Of

The ultraviolet absorption spectra of a variety of naphthalene compounds containing phenyl and carboxy substituents are described. The majority of the compounds contain either the naphthalene-1,2-dicarboxylic acid anhydride or the naphthalene-2,3-dicarboxylic acid anhydride ring systems. It is shown that in ethanolic solution the spectra of these anhydrides change over a period of a few hours. The spectra of the anhydrides in n-heptane or dioxane solution do not change on standing. The effects of the various substituents are discussed in terms of steric inhibition of resonance and of antagonistic and reinforcing actions of the substituents, dependent on the position of substitution. The significance of these data are considered in relation to the general problem of the interpretation of the ultraviolet absorption spectra of complex molecules.

Steric inhibition of resonance and regio- and stereoselectivity in the ring opening of 1-arylsubstituted epoxides

Tetrahedron ◽  
1973 ◽  
Vol 29 (1) ◽  
pp. 199-204 ◽  
Author(s):  
A. Balsamo ◽  
P. Crotti ◽  
B. Macchia ◽  
F. Macchia
Keyword(s):  
Ring Opening ◽  
Steric Inhibition Of Resonance

Steric inhibition of resonance in nitroanilines by ESCA

1974 ◽  
Vol 4 (1) ◽  
pp. 90-92 ◽  
Author(s):  
S. Pignataro ◽  
R. Di Marino ◽  
G. Distefano
Keyword(s):  
Steric Inhibition Of Resonance
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