Title of Thesis
Kinetics and Mechanism of the Gas Phase Thermal
Decomposition of Substituted Cyclopropanes
National Centre for Excellence in Physical
Chemistry / University of Peshawar, Peshawar
|Number of Pages|
|Keywords (Extracted from title, table of contents and
abstract of thesis)|
Kinetics, Mechanism, Gas Phase,
Thermal, Decomposition, Substituted, Cyclopropanes, Arrhenius
The gas phase thermal decomposition of Methyl-cyclopropane carboxylate [MCC] (682-793K, 5-50 Torr), Cis-2- methylcyclopropanecarboxylic acid (cMCCA) (692-753K, 10-70 Torr) , Methylcyclopropanemethanol (MCM) (562-622K, 4-16 Torr) Cis 2-methylcyclopropanemethanol (cMCM) (483-97K, 5 -24 Torr) have been investigated in aged reactions vessels. Arrhenius parameters were determined for homogenous, unimolecular, formation of the isomeric products and for the overall loss of reactions.
The formation of isomeric products and the observed Arrhenius parameters in all the above mentioned studies are consistent with a biradical mechanism in which the methanol, carboxylic groups stabilizes while carboxylate groups destabilises the transition states for If-transfer and, to a lesser extent, the transition state for geometric isomerization.
cMCCA and cMCM underwent first order, reversible geometric isomerization incompetition with structural isomerization. On the basis of biradical mechanism the results provide evidence for the formation of distinguishable biradicals on opening the cMCCA and cMCM rings.
The effect of the surface on the reaction was studied using the packed reaction vessel for the above mentioned substituted cyclopropane.