Steric inhibition of resonance: revision of the principle on the electronic spectra of methyl-substituted acetophenones

: 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.

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A contribution to evaluation of effects of medium on electronic spectra

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19860746 ◽

1986 ◽

Vol 51 (4) ◽

pp. 746-752 ◽

Cited By ~ 3

Author(s):

Vojtěch Bekárek ◽

Juraj Ševčík

Keyword(s):

Gas Phase ◽

Electronic Spectra ◽

Cross Term

Efficiency has been compared of the Bayliss-McRae-Ooshika, Bakhshiev, and cross term methods in evaluation of the effect of medium on electronic spectra of nine indicators of polarity of medium using also the data obtained in gas phase and in perfluorinated hydrocarbons.

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A contribution to evaluation of influence of medium in electronic and infrared spectroscopy

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19821060 ◽

1982 ◽

Vol 47 (4) ◽

pp. 1060-1068 ◽

Cited By ~ 25

Author(s):

Vojtěch Bekárek ◽

Jan Juřina

Keyword(s):

Refractive Index ◽

Infrared Spectroscopy ◽

Correlation Coefficient ◽

Solvent Effects ◽

Electronic Spectra ◽

Relative Permittivity ◽

Solvent Parameters

Dependence of ET(30) of solvent parameters on relative permittivity (ε) and refractive index (n) of solvent has been found for forty solvents in the form ET(30)=29.87 + 72.03 (ε - 1/(2ε + 1)-29.16(ε - 1) (n 2 - 1)/(2ε + 1) (2n2 + 1), the correlation coefficient being 0.958. Relation has been discussed between ET(30) and π solvent parameters and significance of the term (ε - 1). (n2 - 1)/(2ε + 1) (2n2 + 1) has been tested for evaluation of solvent effects in electronic spectra.>

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