KINGAS : calculation of kinetic data of gas-phase reactions

Kingas is a computer program permitting the automatic estimation of kinetic datafor the isomerizations and recombinations of free radicals but also for the unimolecular decompositions of molecules. The calculations are based on the thermochemical kinetics methods proposed by Benson. The calculated rate coefficients depend on the temperature.

If you need some kinetic data calculations, please contact us at : Rene.Fournet@ensic.inpl-nancy.fr

In the case of isomerizations :
A factors are estimated from the following approximate relationship:

Activation energies for isomerization reactions are set equal to the sum of the activation energy for H-abstraction by analogous radical from the substrate and the strain energy of the cyclic transition state. Activation energies of .OOR abstraction of H are taken equal to 58.6 kJ/mol (tertiary H), 71.1 kJ/mol (secondary H), and 83.7 kJ/mol (primary H). Strain energies of the cyclic transition state containing two oxygen atoms are taken equal to 96.2 kJ/mol (four members ring), 64.9 kJ/mol ( five members ring), 35.6 kJ/mol ( six members ring) and 20.9 kJ/mol (seven members ring).

In the case of unimolecular decompositions:

The kinetic data of unimolecular decomposition are obtained from the data of reverse reactions which are recombinations and relevant thermochemical data which are calculated by using the software THERGAS. Activation energies of recombinations are taken equal to 0. So, for a recombination of two free radicals R° and RO° to form a molecular species R-RO, theA factor is estimated from the modified collisions theory, using the following relation:

Relevant Publications

Examples

	Isomerization of free radicals
		Input formula : ch3/ch2/ch(/ch3)/o/o(.)=ch2(.)/ch(/o/oh)/ch2/ch3
	Thermodynamic data for the reaction for the direct reaction (THERGAS)
	Results Temperature (K) Enthalpy change of reaction Entropy change of reaction Free-energy change of reaction Equilibrium constant 750.0 DrHo=58.06 kJ/mole DrSo= 27.50 J/mole.K DrGo= 37.45 kJ/mole K(p) =2.45 E-3
	Kinetic data for the direct reaction
	A1 factor = 3.76 E+12 s-1 Activation energy E1= 148.39 kJ/mol Rate constant k1 at 750 K = 173 s-1
	Kinetic data for the reverse reaction
	A-1 factor = 13.7 E+12 s-1 Activation energy E-1= 90.33 kJ/mol Rate constant k-1 at 750 K = 69300 s-1
	Unimolecular decomposition
		Input formula : ch3/ch2/ch2/ch3=2ch3/ch2(.)
	Thermodynamic data for the reaction for the direct reaction (THERGAS)
	Results Temperature (K) Enthalpy change of reaction Entropy change of reaction Free-energy change of reaction Equilibrium constant 800.0 DrHo=358.76 kJ/mole DrSo= 174.72 J/mole.K DrGo= 218.95 kJ/mole K(p) =0.489E-14
	Kinetic data for the direct reaction
	A1 factor = 0.216E+17 s-1 Activation energy E1= 360.77 kJ/mol Rate constant k1 at 800 K = 0.60E-07 s-1
	Kinetic data for the reverse reaction
	A-1 factor = 0.469E-11 cm3/molecule.s Ratio : k1/k-1 = 0.745E-16