Quantum-chemical study of organic reaction mechanisms: I. Addition of selenium dihalides to the double bond of vinyl ethers

Both the EHT and IEHT methods were used in the study of interaction of various butene forms with models of catalytic active centers (Mo-O-metal), in which the Mo atom is in its +4 or +6 oxidation state and is tetrahedrally or octahedrally coordinated. The influence of an additional metal atom incorporated in the molybdate lattice was also studied. The results suggest that the interaction of all butene forms with the studied models of catalytic surface centers leads to the formation of stable adsorption complexes and that the butene molecule thus chemisorbed can undergo a direct cis-trans or a double-bond isomerization. It is shown that the probability of occurrence of both these reactions depends strongly on the symmetry of the surface center of the catalyst, on the valence of the Mo atom, and increases with the electron acceptor capability of the additional metal.

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QUANTUM CHEMICAL STUDY OF OXIDATION REACTIONS IN UNSATURATED HYDROCARBONS

IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA ◽

10.6060/tcct.2017607.5516 ◽

2017 ◽

Vol 60 (7) ◽

pp. 14

Author(s):

Anna A. Novikova ◽

Mikhail E. Soloviev

Keyword(s):

Double Bond ◽

Thermodynamic Functions ◽

Quantum Chemical ◽

Hydrogen Abstraction ◽

Quantum Chemical Study ◽

Chemical Study ◽

Oxidation Reactions ◽

Double Bonds ◽

Unsaturated Hydrocarbons ◽

The Stability

In this article quantum-chemical calculations using DFT B3LYP/cc-pvdz method was used for the investigation of changes in thermodynamic functions of reactions of oxidation of unsaturated hydrocarbons such as heptane and heptadiene as low-molecular models of hydrocarbon residues of lipids. The effect of the position of the reaction center relative to the double bonds and conformations of double bonds on reactivity of the compounds in reactions of hydrogen abstraction by the hydroxyl radical, dioxygen accession and chain propagation were analyzed. By comparison of changes in thermodynamic functions of reactions it was shown that hydrocarbons with cis- conformations of double bonds are characterized with higher reactivity in reactions of hydrogen abstraction but peroxi-radicals of these conformers are more stable. The changes in thermodynamic functions of reaction of hydrogen abstraction for diene according to the calculation are smaller comparing with olefins. This is due to the difference in the stability of the radicals formed. The stability of hydrocarbon radicals of dienes in comparison with olefins is explained by their planar structure with electron density of unpaired electron delocalized between five carbon atoms. The emergence of such pentadienil-type radicals is the cause of a higher oxidation of dienes compared with olefins. The analysis of molecular structures of peroxi-radicals of dienes shows that after accepting dioxygen by hydrocarbon radical the isomerization takes place. According calculations it is preferable for the dioxygen molecule not to join with the central carbon atom from which the hydrogen atom has been abstracted but to attack the double bond joining with C2 carbon atom. During the isomerization the double bond moves to the center of the molecule forming thus the conjugated pair with the other double bond. Comparison of thermodynamic functions of reaction for cis- and trans- isomers shows that cis-trans isomerization is possible during the dioxygen accession to the hydrocarbon radical. These results are in good agreement with the experimental data published earlier.Forcitation:Novikova A.A., Soloviev M.E. Quantum chemical study of oxidation reactions in unsaturated hydrocarbons. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 7. P. 14-20.

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