Correlations between hardness, electrostatic interactions, and thermodynamic parameters in the decomposition reactions of 3-buten-1-ol, 3-methoxy-1-propene, and ethoxyethene
- 144 Downloads
Decomposition of the three isomeric compounds, 3-buten-1-ol (1), 3-methoxy-1-propene (2), and ethoxyethene (3), at two different (300 and 550 K) temperatures 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 resonance 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 (ΔG ≠) increase from compound 1 to compound 3. The variations of the calculated ΔG ≠ values can not be justified by the decrease of the calculated global hardness (η) differences between the ground and transition states structures (i.e., Δ[η(GS)−η(TS)]). Based on the synchronicity indices, the transition state structures of compounds 1–3 involve synchronous 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 (ΔS ≠) values can not be justified by the decrease of Δ[η(GS)−η(TS)] parameter from compound 1 to compound 3. On the other hand, dipole moment differences between the ground and transition state structures [Δ(µ TS−µ GS)] decrease from compound 1 to compound 3. Therefore, the electrostatic model associated with the dipole–dipole interactions justifies the increase of the calculated ΔG ≠ values from compound 1 to compound 3. The correlations between ΔG ≠, Δ[η(GS)−η(TS)], (ΔS ≠), k(T), electrostatic model, and structural parameters have been investigated.
KeywordsThermal decomposition Reaction mechanism Hardness 3-Buten-1-ol 3-Methoxy-1-propene Ethoxyethene
This work has been supported by the research grant from the Research Council of the Ahvaz Branch, Islamic Azad University. We thank Dr. Daryoush Tahmasebi for CBS-4 calculations.
- 3.Smith GG, Yates BL (1965) J Chem Soc 7242–7246Google Scholar
- 9.Glasstone KJ, Laidler KJ, Erying H (1941) The theory of rate processes Chapter 4. McGraw-Hill, New YorkGoogle Scholar
- 10.Benson SW (1969) The foundations of chemical kinetics. McGraw-Hill, New YorkGoogle Scholar
- 18.Hehri WJ, Radom L, PvR Scheleyer, Pople JA (1986) Ab initio molecular orbital theory. Wiley, New YorkGoogle Scholar
- 20.Seminario JM, Politzer P (eds) (1995) Modern density function theory, a tool for chemistry. Elsevier, AmsterdamGoogle Scholar
- 28.Frisch MJ, Trucks GW, Schlegel HB, Scuseria GE, Robb MA, Cheeseman JR, Zakrzewski VG, Montgomery JA, Stratmann Jr., RE, Burant JC, Dapprich S, Millam JM, Daniels AD, Kudin KN, Strain MC, Farkas O, Tomasi J, Barone V, Cossi M, Cammi R, Mennucci B, Pomelli C, Adamo C, Clifford S, Ochterski J, Petersson GA, Ayala PY, Cui Q, Morokuma K, Malick DK, Rabuck AD, Raghavachari K, Foresman JB, Cioslowski J, Ortiz JV, Stefanov BB, Liu G, Liashenko A, Piskorz P, Komaromi I, Gomperts R, Martin RL, Fox DJ, Keith T, Al-Laham MA, Peng CY, Nanayakkara A, Gonzalez C, Challacombe M, Gill PMW, Johnson B, Chen W, Wong MW, Andres JL, Head-Gordon M, Replogle ES, Pople JA (1998) GAUSSIAN 98, Revision A.3, Gaussian Inc., Pittsburgh, PAGoogle Scholar
- 31.Glasstone KJ, Laidler KJ, Eyring H (1941) The theory of rate processes, Chap 4. McGraw-Hill, New YorkGoogle Scholar
- 37.Dewar MJS (1959) Tetrahedron Lett 16–18Google Scholar