Use of semi empirical method for determination of the activation energy of thermal decomposition of vinyl ethers

Subject Areas : Journal of Physical & Theoretical Chemistry

Behnaz Shahrokh ¹ , Garnik Sargsyan ²

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Received: 2014-09-05 Accepted : 2014-09-05 Published : 2014-09-01

Keywords: Semi empirical, MM2, Vinyl ether, Transition state,

Abstract :

In this research, a semi empirical approach has been suggested for calculating the activation energyof unimolecular thermal decomposition of vinyl ethers yielding saturated products. The calculationprocedure is based on the use of molecular mechanics (MM) methods. These methods which involvethe construction of the transition state for a molecule mainly consider the formation of a “HydrogenBridge” between the alkyl and vinyl groups and also use the Lennard - Jones potential. Theactivation energy of the decay is calculated as the difference between bond energy of the Hydrogenatom jumping from the alkyl group to the vinyl group, and the strain energy of the molecule due tothe formation of the transition state (TS). A new semi empirical method for computing the activationenergy at spontaneous decay of vinyl ethyl ether (VEE), vinyl propyl ether (VPE) and vinyl butylether (VBE) molecules has been developed. It allows calculating the values of the activation energyby simple procedures. The obtained results for the decay of vinyl ethers are in good agreement withthe known experimental data in the literature.