5 research outputs found
Toward the Physical Interpretation of Inductive and Resonance Substituent Effects and Reexamination Based on Quantum Chemical Modeling
No full textDependence of the Substituent Effect on Solvent Properties
No full textThe influence of
a solvent on the substituent effect (SE) in 1,4-disubstituted
derivatives of benzene (BEN), cyclohexa-1,3-diene (CHD), and bicyclo[2.2.2]Âoctane
(BCO) is studied by the use of polarizable continuum model method.
In all X–R–Y systems for the functional group Y (NO<sub>2</sub>, COOH, OH, and NH<sub>2</sub>), the following substituents
X have been chosen: NO<sub>2</sub>, CHO, H, OH, and NH<sub>2</sub>. The substituent effect is characterized by the charge of the substituent
active region (cSARÂ(X)), substituent effect stabilization energy (SESE),
and substituent constants σ or <i>F</i> descriptors,
the functional groups by cSARÂ(Y), whereas Ï€-electron delocalization
of transmitting moieties (BEN and CHD) is characterized by a geometry-based
index, harmonic oscillator model of aromaticity. All computations
were carried out by means of B3LYP/6-311++GÂ(d,p) method. An application
of quantum chemistry SE models (cSAR and SESE) allows to compare the
SE in water solutions and in the gas phase. Results of performed analyses
indicate an enhancement of the SE by water. The obtained Hammett-type
relationships document different nature of interactions between Y
and X in aromatic and olefinic systems (a coexistence of resonance
and inductive effects) than in saturated ones (only the inductive
effect). An increase of electric permittivity clearly enhances communications
between X and Y for BEN and CHD systems
How far the substituent effects in disubstituted cyclohexa-1,3-diene derivatives differ from those in bicyclo[2.2.2]octane and benzene?
No full text
