skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Competitive threshold collision-induced dissociation: Gas-phase acidities and bond dissociation energies for a series of alcohols

Abstract

Energy-resolved competitive collision-induced dissociation methods are used to measure the gas-phase acidities of a series of alcohols (methanol, ethanol, 2-propanol, and 2-methyl-2-propanol). The competitive dissociation reactions of fluoride-alcohol, [F{sup {minus}}{center{underscore}dot}HOR], alkoxide-water, [RO{sup {minus}}{center{underscore}dot}HOH], and alkoxide-methanol [RO{+-}{center{underscore}dot}HOCH{sub 3}] proton-bound complexes are studied using a guided ion beam tandem mass spectrometer. The reaction cross sections and product branching fractions to the two proton transfer channels are measured as a function of collision energy. The enthalpy difference between the two product channels is found by modeling the reaction cross sections near threshold using RRKM theory to account for the energy-dependent product branching ratio and kinetic shift. From the enthalpy difference, the alcohol gas-phase acidities are determined relative to the well-known values of HF and H{sub 2}O. The measured gas-phase acidities are {Delta}{sub acid}H{sub 298}(CH{sub 3}OH) = 1599 {+-} 3 kJ/mol, {Delta}{sub acid}H{sub 298}(CH{sub 3}CH{sub 2}OH) = 1586 {+-} 5 kJ/mol, {Delta}{sub acid}H{sub 298}((CH{sub 3}){sub 2}CHOH) = 1576 {+-} 4 kJ/mol, and {Delta}{sub acid}H{sub 298}((CH{sub 3}){sub 3}COH) = 1573 {+-} 3 kJ/mol.

Authors:
;
Publication Date:
Research Org.:
Univ. of Nevada, Reno, NV (US)
Sponsoring Org.:
USDOE
OSTI Identifier:
20000066
DOE Contract Number:  
FG03-97ER14750
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory
Additional Journal Information:
Journal Volume: 103; Journal Issue: 35; Other Information: PBD: 2 Sep 1999; Journal ID: ISSN 1089-5639
Country of Publication:
United States
Language:
English
Subject:
10 SYNTHETIC FUELS; DISSOCIATION; BOND LENGTHS; ETHANOL; METHANOL; PROPANOLS; BUTANOLS

Citation Formats

DeTuri, V.F., and Ervin, K.M. Competitive threshold collision-induced dissociation: Gas-phase acidities and bond dissociation energies for a series of alcohols. United States: N. p., 1999. Web. doi:10.1021/jp991459m.
DeTuri, V.F., & Ervin, K.M. Competitive threshold collision-induced dissociation: Gas-phase acidities and bond dissociation energies for a series of alcohols. United States. doi:10.1021/jp991459m.
DeTuri, V.F., and Ervin, K.M. Thu . "Competitive threshold collision-induced dissociation: Gas-phase acidities and bond dissociation energies for a series of alcohols". United States. doi:10.1021/jp991459m.
@article{osti_20000066,
title = {Competitive threshold collision-induced dissociation: Gas-phase acidities and bond dissociation energies for a series of alcohols},
author = {DeTuri, V.F. and Ervin, K.M.},
abstractNote = {Energy-resolved competitive collision-induced dissociation methods are used to measure the gas-phase acidities of a series of alcohols (methanol, ethanol, 2-propanol, and 2-methyl-2-propanol). The competitive dissociation reactions of fluoride-alcohol, [F{sup {minus}}{center{underscore}dot}HOR], alkoxide-water, [RO{sup {minus}}{center{underscore}dot}HOH], and alkoxide-methanol [RO{+-}{center{underscore}dot}HOCH{sub 3}] proton-bound complexes are studied using a guided ion beam tandem mass spectrometer. The reaction cross sections and product branching fractions to the two proton transfer channels are measured as a function of collision energy. The enthalpy difference between the two product channels is found by modeling the reaction cross sections near threshold using RRKM theory to account for the energy-dependent product branching ratio and kinetic shift. From the enthalpy difference, the alcohol gas-phase acidities are determined relative to the well-known values of HF and H{sub 2}O. The measured gas-phase acidities are {Delta}{sub acid}H{sub 298}(CH{sub 3}OH) = 1599 {+-} 3 kJ/mol, {Delta}{sub acid}H{sub 298}(CH{sub 3}CH{sub 2}OH) = 1586 {+-} 5 kJ/mol, {Delta}{sub acid}H{sub 298}((CH{sub 3}){sub 2}CHOH) = 1576 {+-} 4 kJ/mol, and {Delta}{sub acid}H{sub 298}((CH{sub 3}){sub 3}COH) = 1573 {+-} 3 kJ/mol.},
doi = {10.1021/jp991459m},
journal = {Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory},
issn = {1089-5639},
number = 35,
volume = 103,
place = {United States},
year = {1999},
month = {9}
}