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

Title: Photoionization mass spectrometric measurements of initial reaction pathways in low-temperature oxidation of 2,5-dimethylhexane

Journal Article · · Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
DOI:https://doi.org/10.1021/jp507811d· OSTI ID:1236002
 [1];  [1];  [1];  [1];  [1];  [1];  [2];  [3];  [4];  [1];  [2];  [1]
  1. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
  2. Univ. of Michigan, Ann Arbor, MI (United States). Applied Physics Program
  3. Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States)
  4. Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Sandia National Lab. (SNL-CA), Livermore, CA (United States)
+ Show Author Affiliations

The product formation from R + O2 reactions relevant to low-temperature autoignition chemistry was studied for 2,5-dimethylhexane, a symmetrically branched octane isomer, at 550 and 650 K using Cl-atom initiated oxidation and multiplexed photoionization mass spectrometry (MPIMS). The interpretation of time- and photon-energy-resolved mass spectra led to three specific results important to characterizing the initial oxidation steps: (1) quantified isomer-resolved branching ratios for HO2 + alkene channels; (2) 2,2,5,5-tetramethyltetrahydrofuran is formed in substantial yield from addition of O2 to tertiary 2,5-dimethylhex-2-yl followed by isomerization of the resulting ROO adduct to tertiary hydroperoxyalkyl (QOOH) and exhibits a positive dependence on temperature over the range covered leading to a higher flux relative to aggregate cyclic ether yield. The higher relative flux is explained by a 1,5-hydrogen atom shift reaction that converts the initial primary alkyl radical (2,5-dimethylhex-1-yl) to the tertiary alkyl radical 2,5-dimethylhex-2-yl, providing an additional source of tertiary alkyl radicals. Furthermore, quantum-chemical and master-equation calculations of the unimolecular decomposition of the primary alkyl radical reveal that isomerization to the tertiary alkyl radical is the most favorable pathway, and is favored over O2-addition at 650 K under the conditions herein. The isomerization pathway to tertiary alkyl radicals therefore contributes an additional mechanism to 2,2,5,5-tetramethyltetrahydrofuran formation; (3) carbonyl species (acetone, propanal, and methylpropanal) consistent with β-scission of QOOH radicals were formed in significant yield, indicating unimolecular QOOH decomposition into carbonyl + alkene + OH.

Research Organization:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
AC04-94AL85000
OSTI ID:
1236002
Report Number(s):
SAND2014-16997J; 536947
Journal Information:
Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory, Vol. 118, Issue 44; ISSN 1089-5639
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 15 works
Citation information provided by
Web of Science

References (33)

Microbial engineering for the production of advanced biofuels journal August 2012
Comparison of Biomass-Derived Turbine Fuels with the Composition-Explicit Distillation Curve Method journal April 2011
Chemical kinetics of hydrocarbon ignition in practical combustion systems journal January 2000
A Fundamentally Based Correlation Between Alkane Structure and Octane Number journal October 1987
Quantum Chemical Investigation of Low-Temperature Intramolecular Hydrogen Transfer Reactions of Hydrocarbons journal September 2006
A comprehensive combustion chemistry study of 2,5-dimethylhexane journal June 2014
Arrhenius parameters of elementary reactions involved in the oxidation of neopentane
  • Baldwin, Robert R.; Hisham, Mohamed W. M.; Walker, Raymond W.
  • Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases, Vol. 78, Issue 5 https://doi.org/10.1039/f19827801615
journal January 1982
Systematic Computational Study on the Unimolecular Reactions of Alkylperoxy (RO 2 ), Hydroperoxyalkyl (QOOH), and Hydroperoxyalkylperoxy (O 2 QOOH) Radicals journal April 2011
High-Pressure Rate Rules for Alkyl + O 2 Reactions. 1. The Dissociation, Concerted Elimination, and Isomerization Channels of the Alkyl Peroxy Radical journal November 2011
High-Pressure Rate Rules for Alkyl + O 2 Reactions. 2. The Isomerization, Cyclic Ether Formation, and β-Scission Reactions of Hydroperoxy Alkyl Radicals journal May 2012
Kinetics of elementary reactions in low-temperature autoignition chemistry journal August 2011
Uncovering the Fundamental Chemistry of Alkyl + O 2 Reactions via Measurements of Product Formation journal April 2006
Detailed chemical kinetic models for the low-temperature combustion of hydrocarbons with application to gasoline and diesel fuel surrogates journal August 2008
Performance of the vacuum ultraviolet high-resolution and high-flux beamline for chemical dynamics studies at the Advanced Light Source journal May 1997
Chemical dynamics, molecular energetics, and kinetics at the synchrotron journal January 2010
The multiplexed chemical kinetic photoionization mass spectrometer: A new approach to isomer-resolved chemical kinetics journal October 2008
New mechanistic insights to the O(3P) + propene reaction from multiplexed photoionization mass spectrometry journal January 2012
Low-temperature combustion chemistry of biofuels: Pathways in the low-temperature (550–700K) oxidation chemistry of isobutanol and tert-butanol journal January 2013
A structure-activity relationship for the estimation of rate constants for the gas-phase reactions of OH radicals with organic compounds journal September 1987
Temperature-dependent rate constants for the reaction of ground-state chlorine with simple alkanes journal August 1980
Evaluated kinetic and photochemical data for atmospheric chemistry: Volume II – gas phase reactions of organic species journal January 2006
Competitive chlorination reactions in the gas phase: hydrogen and C 1 —C 5 saturated hydrocarbons journal January 1959
“Imaging” combustion chemistry via multiplexed synchrotron-photoionization mass spectrometry journal January 2008
Low-temperature combustion chemistry of biofuels: pathways in the initial low-temperature (550 K–750 K) oxidation chemistry of isopentanol journal January 2012
A complete basis set model chemistry. VI. Use of density functional geometries and frequencies journal February 1999
Absolute photoionization cross-section of the propargyl radical journal April 2012
The M06 suite of density functionals for main group thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and transition elements: two new functionals and systematic testing of four M06-class functionals and 12 other functionals journal July 2007
Molpro: a general-purpose quantum chemistry program package: Molpro
  • Werner, Hans-Joachim; Knowles, Peter J.; Knizia, Gerald
  • Wiley Interdisciplinary Reviews: Computational Molecular Science, Vol. 2, Issue 2 https://doi.org/10.1002/wcms.82
journal July 2011
Reformulation and Solution of the Master Equation for Multiple-Well Chemical Reactions journal May 2013
Estimation of Lennard‐Jones (6,12) Pair Potential Parameters from Gas Solubility Data journal October 1971
A Comprehensive Modeling Study of n-Heptane Oxidation journal July 1998
Gas phase oxidation of alkenes—Part II. The oxidation of 2-methylbutene-2 and 2,3-dimethylbutene-2 journal June 1973
Gas-phase oxidation of alkenes: decomposition of hydroxy-substituted peroxyl radicals journal January 1973

Cited By (1)

Mechanisms and kinetics of the low-temperature oxidation of 2-methylfuran: insight from DFT calculations and kinetic simulations journal January 2020

Similar Records

Isomer-Dependent Reaction Mechanisms of Cyclic Ether Intermediates: cis-23-Dimethyloxirane and trans-23-Dimethyloxirane.
Journal Article · Tue Oct 06 00:00:00 EDT 2020 · International Journal of Chemical Kinetics · OSTI ID:1236002
+7 more
Reaction mechanisms of a cyclic ether intermediate: Ethyloxirane
Journal Article · Mon Sep 21 00:00:00 EDT 2020 · International Journal of Chemical Kinetics · OSTI ID:1236002
+7 more
Subsequent R + O2 Chemistry of Intermediates Formed in Low-Temperature R + O2 Reactions: Potential Importance in Modeling Autoignition Behavior
Technical Report · Tue Aug 01 00:00:00 EDT 2017 · OSTI ID:1236002

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
octane isomer
2
2
5
5-tetramethyl-tetrahydrofuran
bisabolane
autoignition chemistry
photoionization mass spectrometry