CC BY
9
ХИМИЯ
УДК 547.512:544.183.26
V. A. Babkin, D. S. Andreev, A. N. Liberovskaya, V. T. Fomichev, I. Y. Velikodniy, K. Yu. Prochuhan, A. A. Krutilin, G. E. Zaikov
QUANTUM CHEMICAL STUDY OF THE MECHANISM PROTONATION 3-METHYLBUTENE-1
MNDO METHOD
Keywords: mechanism protonation, method MNDO, 3-methylbutene-1, heat of reaction.
For the first time it is researched of classical quantum chemical method MNDO of modeling mechanism protonation of 3-methylbutene-1 - monomer of cationic polymerization. Showing, that he considerate some self usual mechanism connection proton to olefin corresponding Morkovnikov's rule. Reaction exothermic and carry without a barrier character. Prize energy in result of reaction - 490 kDg/mol.
Ключевые слова: механизм протонирования, метод MNDO, 3-метилбутен-1.
Впервые исследован механизм протонирования 3-метилбутена-1 классическим квантово-химическим методом MNDO. Реакция экзотермична и имеет безбарьерный характер. Тепловой эффект реакции равен 490 кДж/моль.
Introduction
It is logical to start the research of 3-methylbutene-1 elementary act mechanisms (initiation, growth of a material chain and chain termination) in the presence of a different cationic accelerants (usually it is complex acids of Lewis and Brensted)[1]from study ofmechanism of the monomer protonation, which is the first step in researching of its elementary act mechanism of cationic polymerization initiation. In this regard, the purpose of this paper is a quantum chemical research of the 3-methylbutene-1protonation mechanism by classic semi empiric MNDO method.
Methodic part
The classic quantum chemical MNDO method was chosen for study the monomer protonation mechanism of 3-methylbutene-Icationic polymerization. This method are incorporate into Firefly [2], which is partially based on GAMESS source code [3] and it uses gradient optimization method of all geometry parameters. MNDO method are parameterized specially for the best energy characteristic reproduction of molecular systems[4], that is an important factor for the analysis of mechanism of cationic processes. The approximation of isolated molecule in gas phase within the molecular model was used in the estimation. There are 16 atoms in the H+ ... C5HI0 (3-methylbutene-1) system,M=2S+1=1(where S - total spin of all electrons of the studied system, S is equal zero (all electrons are paired), M - multiplicity), total charge of the molecular system is X qc =1. 3-methylbutene-1protonation mechanism was closely studied by the method, which was described in the paper [5]. Received data of energy along acoordinate of reaction were used for building equipotential surface of 3-methylbutene-1 and proton interaction (Fig. 4). The original model of reaction between proton and 3-methylbutene-1 was shown at the Fig. 1. (The distances from Hj to C2 (RH1C2) and from Hj to C3 (RH1C3) were chosen as the coordinate of reaction, step of the reaction coordinate is equal 0.01 nm).
Fig. 1 - The original model of reaction between proton and 3-methylbutene-1
The MacMolPlt[6] program was used for evident representation of the studied molecular systems.
Estimation results
Potential energy surface of the reactions between proton and 3-methylbutene-1 was shown at the Fig. 4. The final structure of formed carbocation after the reaction between proton HI and the alpha-carbon atom of 3-methylbutene-1(C2) and the rupture of 3-methylbutene-1double bond was shown at the Fig. 2. The final structure of formed carbocation after the reaction between proton Hi and the beta-carbon atom of 3-methylbutene-1(C3) and the rupture of C2 = C3double bond was shown at the Fig. 3. Total energy change along the way of reaction of addition of proton H1 to the alpha-carbon atom of 3-methylbutene-1 was shown at the Fig. 4, where the negative values of total energy of the systemH+ ... CsH^Eq) increase up to full forming of carbocation (see Fig. 5) and have barrier-free pattern under the attack both alpha-carbon and beta-carbonatom of 3-methylbutene-1(see Fig. 7)on the all movement
way of proton (initiating particle) H+ along the coordinate of reaction between Rh1C2hRh1C3. However the final structure of the reaction between proton and the alpha-carbon atom is 57 kJ/mol more profitable than the final structure of the reaction between proton and the beta-carbon atom. Heating value of the reaction between proton and the alpha-carbon atom is 490 kJ/mol but heating value of the reaction between proton and the alpha-carbon atom is 433 kJ/mol. Besides result analysis of quantum chemical estimations and changes of force lengths, bond angles and charges on atoms along the coordinate of the reaction at both options (see Fig. 8 and 6) under the proton attack both alpha-carbon and beta-carbon atom of 3-methylbutene-1 shows, that the protonation mechanism of 3-methylbutene-1 cationic polymerization executes by the addition of proton to monomer's double bond classic scheme.
Conclusion
Thus, for the first time we have studied the protonation mechanism of 3-methylbutene-1 by the quantum chemical MNDO method. It shows that this mechanism is an ordinary addition of proton to double bond olefin. The reaction is exothermic and barrier-free.
Fig. 2 -The final structure of formed carbocation after the reaction between proton H1 and the alphacarbon atom of 3-methylbutene-1(C2)
Fig. 4 - Equipotentialenergy surface of 3-methylbutene-1 and proton interaction
Fig. 5 - Total energy change along the way of reaction of addition of proton H1 to the alphacarbon atom of 3-methylbutene-1
Fig. 3 - The final structure of formed carbocation after the reaction between proton H1 and the betacarbon atom of 3-methylbutene-1(C3)
Fig. 6 - Charge change on some atoms along the way of reaction of addition of proton H1 to the alphacarbon atom of 3-methylbutene-1
ÛE, кДж/мол 0 —!-
-50 ■100
-150
250
300
400 -450 500
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Номер ступени
Fig. 7 - Total energy change along the way of reaction of addition of proton Н1 to the beta-carbon atom of 3-methylbutene-1
¿q Номер ступени
1 2 3 4 Б 6 7 8 9 10 11 12 13 14 IE 16 17 18 19 20 21
Reference
1. Kennedy, John. The Cationic Polymerization of Olefins / J. Kennedy. - M., 1978. - 431 p.
2.AlexA.Granovsky, Firefly version 8, www http://classic.chem.msu.su/gran/firefly/index.html
3.Shmidt, M.W. J. Comput. Chem. / M. W. Shmidt, M. S. Gordon [and another]. - 1993. - 14. - P. 1347-1363.
4. Tsirel'son V.G. Quantum Chemistry. Molecules, Molecular Systems and Solids. Publishing house "Bean", Moscow, 2010, 496 p.
5. Andreev D.S., Babkin V.A., Zaikov G.E. Quantum-chemical Study of the Mechanism of Initiation of an Isoolefin 2-methyl-1 in the Presence of Aluminum Chloride Aqua Complex. "Bulletin" Kazan Technological University. 2015., T.18, №1, s.28-31.
6.Bode, B. M.J. Mol. Graphics Mod / B. M. Bode, M. S. Gordon. - 1998. -6. - P.133-138.
Fig. 8 - Charge change on some atoms along the way of reaction of addition of proton H1 to the betacarbon atom of 3-methylbutene-1
© V. A. Babkin - Doctor of Chemical Sciences, professor, academician of Russian Academy of Natural History, academician of international academy "Contenant", E-mail: [email protected]; D. S. Andreev - graduate student of Volgograd State Technical University. E-mail: [email protected]; A. N. Liberovskaya — professor of department "Technical disciplines and heat power engineering" of Volgograd State Technical University, Sebryakov's Branch; V. T. Fomichev — Doctor of Engineering Sciences, professor of department "Applied Chemistry" of Volgograd State Architecture Building University. E-Mail: [email protected]; 1 Y. Velikodniy - Magistrant of Engineering of Volgograd State Technical University, Sebryakovsky Branch; K Yu. Prochukhan — Candidate of Chemical Sciences, professor of HMC department of Bashkir State University, e-mail: [email protected]; A. A. Krutilin — Candidate of Engineering Sciences, professor of department "Construction materials and building technologies" of Volgograd State Technical University, Sebryakov's Branch. E-mail: [email protected]; G. E. Zaikov - Doctor of Chemical Sciences, professor, academician of international academyof Science (Munich, Germany), Honored scientist of Russian Federation. Institute of Biochemical Physics, Moscow. E-mail: [email protected].
© В. А. Бабкин - д.х.н., профессор, академик РАЕ. Себряковский филиал Волгоградского государственного технического университета, [email protected]; Д. С. Андреев - преподаватель Волгоградского государственного технического университета, [email protected], А. Н. Либеровская - доцент, кафедра ТД и ТЭ Себряковский филиал Волгоградского государственного технического университета; В. Т. Фомичев - д.т.н., профессор, зав. каф. «Прикладной и общей химии» ИА и С ВолгГТУ; И. Ю. Великодный - магистрант, группа МС-21д Себряковский филиал Волгоградского государственного технического университета; К. Ю. Прочухан - к.х.н., доцент, кафедра «Высокомолекулярных соединений» Башкирский государственный университет. [email protected]; А. А. Крутилин - к.т.н., доцент каф. ОТД Себряковский филиал Волгоградского государственного технического университета [email protected]; Г. Е. Заиков - д.х.н., профессор каф ТПМ КНИТУ, академик международной академии творчества (Москва-Сан - Диего Россия-США). [email protected].
