Photoelectron spectroscopy, gas phase acidity, and thermochemistry of {ital tert}-butyl hydroperoxide: Mechanisms for the rearrangement of peroxyl radicals

Journal Article · Tue Dec 01 00:00:00 EST 1998 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.477725· OSTI ID:670192

Clifford, E P ^[1]; Wenthold, P G ^[2]; Gareyev, R ^[1]; Lineberger, W C ^[2]; DePuy, C H; Bierbaum, V M; Ellison, G B ^[1]

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1. Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States)
2. JILA and the Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440 (United States)

The 3.531 eV negative ion photoelectron spectra of the hydroperoxide ion and the {ital tert}-butylperoxide ion have been studied. We find HO{sub 2}{sup {minus}}+{h_bar}{omega}{sub 351.1thinspnm}{r_arrow}HO{sub 2}+e{sup {minus}} EA[HO{sub 2},{tilde X}thinsp{sup 2}A{sup {double_prime}}]=1.089{plus_minus}0.006thinspeV, (CH{sub 3}){sub 3}COO{sup {minus}}+{h_bar}{omega}{sub 351.1thinspnm}{r_arrow}(CH{sub 3}){sub 3}COO+e{sup {minus}} EA[(CH{sub 3}){sub 3}COO,{tilde X}thinsp{sup 2}A{sup {double_prime}}]=1.196{plus_minus}0.011thinspeV. The photoelectron spectra show detachment to the ground state of the peroxyl radicals and to a low lying electronic state. The intercombination gaps are measured to be {Delta}E({tilde X}thinsp{sup 2}A{sup {double_prime}}{endash}{tilde A}thinsp{sup 2}A{sup {prime}})[HO{sub 2}]=0.871{plus_minus}0.007thinspeV and {Delta}E({tilde X}thinsp{sup 2}A{sup {double_prime}}{endash}{sup 2}A{sup {prime}})[(CH{sub 3}){sub 3}COO]=0.967{plus_minus}0.011 eV. The gas phase acidity of (CH{sub 3}){sub 3}COOH was measured in a tandem flowing afterglow-selected ion flow tube (FA-SIFT) to be {Delta}{sub acid}G{sub 298}=363.2{plus_minus}2.0thinspkcalthinspmol{sup {minus}1} and we find {Delta}{sub acid}H{sub 298}[(CH{sub 3}){sub 3}COO{endash}H]=370.9{plus_minus}2.0thinspkcalthinspmol{sup {minus}1}. Use of {Delta}{sub acid}H{sub 298}[(CH{sub 3}){sub 3}COO{endash}H] and EA[(CH{sub 3}){sub 3}COO] leads to the bond energies DH{sub 298}[(CH{sub 3}){sub 3}COO{endash}H]=85{plus_minus}2thinspkcalthinspmol{sup {minus}1} and D{sub 0}[(CH{sub 3}){sub 3}COO{endash}H]=83{plus_minus}2thinspkcalthinspmol{sup {minus}1}. The thermochemistry of the alkylperoxyl radicals, RO{sub 2}, is reviewed. A mechanism for the rearrangement of chemically activated peroxyl radicals is proposed [RO{sub 2}]{tilde X}thinsp{sup 2}A{sup {double_prime}}{r_arrow}[RO{sub 2}]{sup {asterisk}}{tilde A}thinsp{sup 2}A{sup {prime}}{r_arrow}aldehydes/ketones+HO({sup 2}{Pi}), [RO{sub 2}]{tilde X}thinsp{sup 2}A{sup {double_prime}}{r_arrow}[RO{sub 2}]{sup {asterisk}}{tilde A}thinsp{sup 2}A{sup {prime}} {r_arrow}alkenes+HO{sub 2}({tilde X}thinsp{sup 2}A{sup {double_prime}}). {copyright} {ital 1998 American Institute of Physics.} thinsp

• OSTI ID: 670192
• Journal Information: Journal of Chemical Physics, Vol. 109, Issue 23; Other Information: PBD: Dec 1998
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
40 CHEMISTRY
ORGANIC COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
THERMOCHEMICAL PROCESSES
PEROXY RADICALS
COMBUSTION PRODUCTS
HYDROCARBONS
OXIDATION
ATMOSPHERIC CHEMISTRY
PH VALUE