Affiliation:
1. Department of Chemistry, Institute of Macromolecular Compounds, Russian Academy of Sciences, 199004 St. Petersburg, Russia
Abstract
:
The present review discusses a new viewpoint on refractometry as the oldest experimental
physical method, whose scientific potential in the estimation of structural effects in
organic chemistry has been missed so far. The author demonstrates that upon certain adjustment
and redesign of refractometry, this potential can be tapped and successfully used to determine
a type of π-electron interaction, delocalization degree of π-electrons in organic compounds,
and to perform quantitative estimates of resonance effects in unsaturated, (polycyclic)
aromatic, and other polyconjugated systems (e.g., fullerenes). The method for accurate separation
of molar refraction into additive and constitutive components was suggested; the method
is based on the specially developed additive scheme. It was revealed that the negative deviations
from additivity for cycloalkanes depend linearly on the number of carbon atoms in the
ring. Excellent linear correlations between renewed optical exaltations, the number of π-electrons in a conjugated
system, and experimentally found resonance energy (determined from hydrogenation heat values) were demonstrated.
Angular coefficients of the correlation series (ρ-constants) are considered as a criterion of classification, which
characterizes the degree of mobility of π-electrons in the conjugated system of a given type. It is emphasized that
the development of methods for precise measurement of the constitutive components of molar refraction may become
a useful additional source of information about resonance and other effects in organic and polymer chemistry.
Publisher
Bentham Science Publishers Ltd.