Computational prediction of α/β selectivities in the pyrolysis of oxygen-substituted phenethyl phenyl ethers

被引:62
作者
Beste, Ariana [1 ]
Buchanan, A. C., III [2 ]
Harrison, Robert J. [1 ,3 ]
机构
[1] Oak Ridge Natl Lab, Div Math & Comp Sci, Oak Ridge, TN 37831 USA
[2] Oak Ridge Natl Lab, Div Chem Sci, Oak Ridge, TN 37831 USA
[3] Univ Tennessee, Dept Chem, Knoxville, TN 37996 USA
关键词
D O I
10.1021/jp800767j
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Phenethyl phenyl ether (PPE; PhCH2CH2OPh) is the simplest model for the most common beta-O-4 linkage in lignin. Previously, we developed a computational scheme to calculate the alpha/beta product selectivity in the pyrolysis of PPE by systematically exploiting error cancellation in the computation of relative rate constants. The alpha/beta selectivity is defined as the selectivity between the competitive hydrogen abstraction reaction paths on the alpha- and beta-carbons of PPE. We use density functional theory and employ transition state theory where we include diagonal anharmonic correction in the vibrational partition functions for low frequency modes for which a semiclassical expression is used. In this work we investigate the effect of oxygen substituents (hydroxy, methoxy) in the para position on the phenethyl ring of PPE on the alpha/beta selectivities. The total alpha/beta selectivity increases when substituents are introduced and is larger for the methoxy than the hydroxy substituent. The strongest effect of the substituents is observed for the alpha-pathway of the hydrogen abstraction by the phenoxyl chain carrying radical for which the rate increases. For the P pathway and the abstraction by the R-benzyl radical (R = OH,OCH3) the rate decreases with the introduction of the substituents. These findings are compared with results from recent experimental studies.
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收藏
页码:4982 / 4988
页数:7
相关论文
共 23 条
  • [1] Ab initio studies on the molecular conformation of lignin model compounds I.: Conformational preferences of the phenolic hydroxyl and methoxy groups in guaiacol
    Agache, C
    Popa, VI
    [J]. MONATSHEFTE FUR CHEMIE, 2006, 137 (01): : 55 - 68
  • [2] Adiabatic approximations to internal rotation
    Allen, Wesley D.
    Bodi, Andras
    Szalay, Viktor
    Csaszar, Attila G.
    [J]. JOURNAL OF CHEMICAL PHYSICS, 2006, 124 (22)
  • [3] APRA E, 2005, NWCHEM COMPUTATIONAL, P99352
  • [4] Vibrational zero-point energies and thermodynamic functions beyond the harmonic approximation
    Barone, V
    [J]. JOURNAL OF CHEMICAL PHYSICS, 2004, 120 (07) : 3059 - 3065
  • [5] Production of hydrogen by lignins fast pyrolysis
    Laboratoire des Sciences du Génie Chimique, CNRS-ENSIC, 1, rue Grandville, BP 20451, 54001 Nancy Cedex, France
    [J]. Int J Hydrogen Energy, 2006, 15 (2179-2192):
  • [6] DENSITY-FUNCTIONAL THERMOCHEMISTRY .3. THE ROLE OF EXACT EXCHANGE
    BECKE, AD
    [J]. JOURNAL OF CHEMICAL PHYSICS, 1993, 98 (07) : 5648 - 5652
  • [7] Ab initio study of hydrogen abstraction reactions on toluene and tetralin
    Beste, Ariana
    Buchanan, A. C., III
    Britt, Phillip F.
    Hathorn, Bryan C.
    Harrison, Robert J.
    [J]. JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM, 2008, 851 (1-3): : 232 - 241
  • [8] Kinetic analysis of the pyrolysis of phenethyl phenyl ether:: Computational prediction of α/β-selectivities
    Beste, Ariana
    Buchanan, A. C., III
    Britt, Phillip F.
    Hathorn, Bryan C.
    Harrison, Robert J.
    [J]. JOURNAL OF PHYSICAL CHEMISTRY A, 2007, 111 (48) : 12118 - 12126
  • [9] THERMOLYSIS OF PHENETHYL PHENYL ETHER - A MODEL FOR ETHER LINKAGES IN LIGNIN AND LOW-RANK COAL
    BRITT, PF
    BUCHANAN, AC
    MALCOLM, EA
    [J]. JOURNAL OF ORGANIC CHEMISTRY, 1995, 60 (20) : 6523 - 6536
  • [10] Oxygen substituent effects in the pyrolysis of phenethyl phenyl ethers
    Britt, Phillip F.
    Kidder, Michelle K.
    Buchanan, A. C., III
    [J]. ENERGY & FUELS, 2007, 21 (06) : 3102 - 3108