The Estimate Transition State Because Conjunction Molecules Ethylene
and Oxygen, with Kinetics Viewpoint.
Shapour.Ramazani*, Ali.Amirmahmodi and Mehdi.Baghernejad
Department of Chemistry, University of Yasouj, Yasouj, Iran
Department of Chemistry, Islamic Azad University of Gachsaran, Gachsaran, Iran
Department of Chemistry, Islamic Azad University of Gachsaran, Gachsaran, Iran
(Email:Ali.Amirmahmodi@yahoo.com)
Keywords: transition state, potential energy level, chemical stability, chemical kinetics.
Abstract:
In this research, kinetics and stability of Ethylene, Oxygen reactions in gas phase has been
considered by semi experimental methods and (mp2/6-311++G**) headline.
The rout of this reaction and its potential energy curve is calculated and molecules situation
from reactant to Transition State and then until product formation is viewable and the best of
transition state has been estimated from optimum energies and frequency test.
1- Introduction:
On the basis of Arnious formula in chemical kinetics which define essence of energy levels
for chemical active systems, the phrase e
 Ea
RT
a kind of energy inhibitor exist between
reactant materials and the products that cause separation these two categories of material.
When molecule Oxygen attack to Ethylene , assuming being enough amount of clash energy
and suitable spatial orientation , there are valleys and heaps proportionate with to become
weak the bonding between Hydrogen from Ethylene and formation new bonding H-O2, in this
case the zone between these valley, in the reactions rout, is not look like basin, perhaps
appearance saddle point.
Of course in mechanical quantum there is some problem such as being individual electrons in
T.S and unstability of T.S that cause disorder spectroscopy process also existence of high
level energy dam and necessity to a lot of points in small interatomic distance to make
potential energy levels. But there are a few exact potential energy level by mechanical
quantum methods.
1
2- Procedure of calculation:
In this research, calculation is performed by gaussian 2009 software and (mp2/6-311++G**)
method such reactant and T.S and products have been Optimized by this method and also
frequency test has been done from Optimized energy to measure the degree of stability on
reaction rout and reaching to T.S.
3- Conclusion:
In this research, molecules Ethylene and Oxygen bring near together from 1.47213A distance
with 0.01 A equal steps while the desirable product will form. Then we draw potential
energy curve on basis of kj
against reaction rout. (curve1) it is observed the top of curve
mol
points is related to T.S with these data: Optimized Energy = -597610.1841 kj
and
mol
Frequency = 3.96 cm 1 also in table 1, there is calculated frequencies from Optimized
energies (for reactant, T.S, product) and we can compare amount of energy and T.S frequency
by using this table.
Curve1: potential energy reaction curve.
Molecules
C2H4
O2
C2H4O2(TS)
C2H3
HO2
frequences[Cm-1]
756.41,829.86,957.02,1058.13,1237.70,1382.23,
1481.67,1675.06,3174.49,3192.13,3264.20,3290.89
1257.88
3.96,47.69,54.12,68.53,81.07,829.15,916.42,
966.94,1064.30,1237.03,1251.00,1381.71,1481.43,
1671.89,3173.71,3191.27,3264.08,3291.03
737.65,957.88,1032.23,1084.29,1427.21,1853.06,
3136.19,3241.44,3307.49
1230.07,1450.75,3709.85
Table1: frequencies of reactant, T.S and products.
2
Enrgy[KJ/mol]
-204934.1526
-392678.8544
-597610.1841
-203270.9558
-394409.0624
4- References:
1- Aghaei . h. 139-physical chemistry, Tehran science and researchs university publishing.
2- Veston- schawrtz/ Abtahi zade. H, 1364, chemical kinetic Tehran university publishing
center.
3- Najaf poor. j/sajadi. A, 1388, energy distribution study, shahre ray Azad Islamic university.
4- Emdee, j.L. Brenzinsky, k; Glassman I. j . phys, chem. 1992.
5- Keit j. Laider, chemical kineticks, 3rd Edition, 1987.
6- perr.t , Pierre. Atoz of Thermodynamics. Oxford university, 1998
7- moller, Christian; plesset, Milton. Phys. Rev, 1934.
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