Enthalpies of formation and bond dissociation energies of lower alkyl hydroperoxides and related hydroperoxy and alkoxy radicals.
The enthalpies of formation and bond dissociation energies, D(ROO-H), D(RO-OH), D(RO-O), D(R-O 2) and D(R-OOH) of alkyl hydroperoxides, ROOH, alkyl peroxy, RO, and alkoxide radicals, RO, have been computed at CBS-QB3 and APNO levels of theory via isodesmic and atomization procedures for R = methyl, ethyl, n-propyl and isopropyl and n-butyl, tert-butyl, isobutyl and sec-butyl. We show that D(ROO-H) approximately 357, D(RO-OH) approximately 190 and D(RO-O) approximately 263 kJ mol (-1) for all R, whereas both D(R-OO) and D(R-OOH) strengthen with increasing methyl substitution at the alpha-carbon but remain constant with increasing carbon chain length. We recommend a new set of group additivity contributions for the estimation of enthalpies of formation and bond energies.
Simmie
John M
JM
Combustion Chemistry Centre, National University of Ireland, Galway, Ireland. john.simmie@nuigalway.ie
Black
Gráinne
G
Curran
Henry J
HJ
Hinde
John P
JP
D002244:Carbon / Q000737:chemistry; D002627:Chemistry, Physical / Q000379:methods*; D005609:Free Radicals; D006859:Hydrogen / Q000737:chemistry; D006860:Hydrogen Bonding; D006861:Hydrogen Peroxide / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D010087:Oxides / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D012984:Software; D013816:Thermodynamics
D005609:Free Radicals; D010087:Oxides; D002244:Carbon; D006859:Hydrogen; D006861:Hydrogen Peroxide; D010100:Oxygen