Correlations between hardness, electrostatic interactions, and thermodynamic parameters in the decomposition reactions of 3-buten-1-ol, 3-methoxy-1-propene, and ethoxyethene
Date
2014-08-11
Journal Title
Journal ISSN
Volume Title
Publisher
Structural Chemistry
Abstract
Decomposition of the three isomeric com pounds, 3-buten-1-ol (1), 3-methoxy-1-propene (2), and
ethoxyethene (3), at two different (300 and 550 K) tem peratures has been investigated by means of ab initio
molecular orbital theory (MP2/6-311?G**//B3LYP/6-
311?G**), hybrid-density functional theory (B3LYP/6-
311?G**), the complete basis set, nuclear magnetic reso nance analysis, and the electrostatic model associated with
the dipole–dipole interactions. All three levels of theory
showed that the calculated Gibbs free energy differences
between the transition and ground state structures (DG=)
increase from compound 1 to compound 3. The variations
of the calculated DG= values can not be justified by the
decrease of the calculated global hardness (g) differences
between the ground and transition states structures (i.e.,
D[g(GS)-g(TS)]). Based on the synchronicity indices, the
transition state structures of compounds 1–3 involve syn chronous aromatic transition structures, but there is no
significant difference between their calculated
synchronicity indices. The optimized geometries for the
transition state structures of the decomposition reactions of
compounds 1–3 consist in chair-like six-membered rings.
The variation of the calculated activation entropy (DS=)
values can not be justified by the decrease of D[g(GS)-
g(TS)] parameter from compound 1 to compound 3. On the
other hand, dipole moment differences between the ground
and transition state structures [D(lTS-lGS)] decrease from
compound 1 to compound 3. Therefore, the electrostatic
model associated with the dipole–dipole interactions jus tifies the increase of the calculated DG= values from
compound 1 to compound 3. The correlations between
DG=, D[g(GS)-g(TS)], (DS=), k(T), electrostatic model,
and structural parameters have been investigated.
Description
Keywords
chemical engineering