title: Structures and energetics of unimolecular thermal degradation of isopropyl butanoate as a model biofuel: density functional theory and ab initio studies.
abstract: Density functional theory (DFT)/BMK and CBS-QB3 ab initio calculations have been carried out to study the structures and energetics of unimolecular decomposition reactions of isopropyl butanoate (IPB, C(3)H(7)C(O)OCH(CH(3))(2)) as a model biofuel. The results show a good performance of the BMK method. Among seven different dissociation channels of IPB, formation of butanoic acid and propene via a six-membered ring transition state is the most favorable reaction. On the other hand, formation of lower esters is hindered by high-energy barriers and unlikely occurs except at elevated temperatures. Simple bond scission costs less energy than lower ester formation. A comparison with methyl and ethyl esters indicates faster decomposition of IPB. The changes in bond lengths along minimum energy paths are discussed.
authors.affiliation: Chemistry Department, Faculty of Science, El-Menoufia University, Shebin El-Kom, Egypt. amelnahas@hotmail.com
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: El-Nahas
authors.forename: Lobna A
authors.initials: LA
authors.lastname: Heikal
authors.forename: Ahmed H
authors.initials: AH
authors.lastname: Mangood
authors.forename: El-Sayed E
authors.initials: el-SE
authors.lastname: El-Shereefy
mesh_terms: D019840:2-Propanol / Q000737:chemistry*; D056804:Biofuels; D002087:Butyrates / Q000737:chemistry*; D003198:Computer Simulation; D006358:Hot Temperature; D008954:Models, Biological; D011789:Quantum Theory; D013816:Thermodynamics
chemical_list: D056804:Biofuels; D002087:Butyrates; D019840:2-Propanol