Correlations between hardness, electrostatic interactions, and thermodynamic parameters in the decomposition reactions of 3-buten-1-ol, 3-methoxy-1-propene, and ethoxyethene

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Date
2014-08-11
Authors
HASANZADEH, Neda
NORİ-SHARGH, Davood
KAYI, Hakan
JAVID, Nargess Rezai
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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.
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chemical engineering
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