Base-induced decomposition of alkyl hydroperoxides in the gas phase. Part 3. Kinetics and dynamics in HO-+CH3OOH, C2H5OOH, and tert-C4H9OOH reactions
Data(s) |
21/06/2008
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Resumo |
The E-CO(2) elimination reactions of alkyl hydroperoxides proceed via abstraction of an (x-hydrogen by a base: X- + (RRHCOOH)-R-1-H-2 -> HX + (RRC)-R-1-C-2=O + HO-. Efficiencies and product distributions for the reactions of the hydroxide anion with methyl, ethyl, and tert-butyl hydroperoxides are studied in the gas phase. On the basis of experiments using three isotopic analogues, HO- + CH3OOH, HO- + CD3OOH, and H18O- + CH3OOH. the overall intrinsic reaction efficiency is determined to be 80% or greater. The E(CO)2 decomposition is facile for these methylperoxide reactions, and predominates over competing proton transfer at the hydroperoxide moiety. The CH3CH2OOH reaction displays a similar E(CO)2 reactivity, whereas proton transfer and the formation of HOO- are the exclusive pathways observed for (CH3)(3)COOH, which has no (x-hydrogen. All results are consistent with the E-CO(2) mechanism, transition state structure, and reaction energy diagrams calculated using the hybrid density functional B3LYP approach. Isotope labeling for HO- + CH3OOH also reveals some interaction between H2O and HO- within the E(CO)2 product complex [H2O center dot center dot center dot CH2=O center dot center dot center dot HO-]. There is little evidence, however. for the formation of the most exothermic products H2O + CH2(OH)O-, which would arise from nuclephilic condensation of CH2=O and HO-. The results suggest that the product dynamics are not totally statistical but are rather direct after the E-CO(2) transition state. The larger HO- + CH3CH2OOH system displays more statistical behavior during complex dissociation. |
Formato |
application/pdf |
Identificador | |
Publicador |
American Chemical Society |
Relação |
http://eprints.qut.edu.au/71658/1/Base-Induced_Decomposition.pdf http://pubs.acs.org/doi/pdf/10.1021/jp800702z DOI:10.1021/jp800702z Kato, S., Ellison, G. B., Bierbaum, V. M., & Blanksby, Stephen J. (2008) Base-induced decomposition of alkyl hydroperoxides in the gas phase. Part 3. Kinetics and dynamics in HO-+CH3OOH, C2H5OOH, and tert-C4H9OOH reactions. Journal of Physical Chemistry A, 112(39), pp. 9516-9525. |
Direitos |
Copyright 2008 American Chemical Society |
Fonte |
School of Chemistry, Physics & Mechanical Engineering; Science & Engineering Faculty |
Palavras-Chave | #s(n)2 nucleophilic-substitution #elimination-reactions #reaction-path #organic radicals #negative-ion #e2 reactions #hydroxide #density #thermochemistry #temperature |
Tipo |
Journal Article |