Reaction kinetics of hydrogen abstraction reactions by hydroperoxyl radical from 2-methyltetrahydrofuran and 2,5-dimethyltetrahydrofuran.

Highly accurate rate parameters for H-abstraction reactions by HO2 radicals are needed for development of predictive chemical kinetic models for ignition. In this article, we report the rate coefficients for reaction of hydroperoxyl radical (HO2) with 2-methyltetrahydrofuran (MTHF) and 2,5-dimethyltetrahydrofuran (DMTHF) computed employing CBS-QB3 and CCSD(T)/cc-pVTZ//B3LYP/cc-pVTZ level of theory in the temperature range of 500-2000 K. Conventional transition state theory (CTST) with hindered rotor approximation for low frequency torsional modes and RRHO (rigid-rotor harmonic oscillator) approximation for all other vibrational modes is employed to evaluate the high pressure rate constants as a function of temperature. Rate constant of each individual hydrogen abstraction channel is taken into account to calculate the overall rate constant. Three-parameter Arrhenius expressions have been obtained by fitting to the computed rate constants of all abstraction channels between 500 and 2000 K. Eight transition states have been identified for MTHF and four for slightly more stable trans-DMTHF. Intrinsic reaction coordinates (IRC) calculations were performed to verify the connectivity of all the transition states (TSs) with reactants and products. One dimensional Eckart's asymmetrical method has been used to calculate quantum mechanical tunneling effect. Results of the theoretically calculated rate coefficients indicate that the hydrogen abstraction by HO2 from the C2 carbon of both MTHF and DMTHF is the most dominant path among all reaction pathways attributed to its lowest barrier height. The total rate coefficients of the MTHF and DMTHF with HO2 at CCSD(T)/cc-pVTZ//B3LYP/cc-pVTZ level of theory are k(T) = 8.60T(3.54) exp(-8.92/RT) and k(T)= 3.17T(3.63) exp(-6.59/RT) cm(3) mol(-1) s(-1), respectively. At both the level of theories, the predicted total abstraction rate constant for DMTHF is found to be higher as compared to that of MTHF over an entire temperature range of investigation. The overall rate constant calculated at CCSD(T)/cc-pVTZ//B3LYP/cc-pVTZ level of theory is lower by 1.43 and 3.44 times at 2000 K than the CBS-QB3 level for MTHF and DMTHF, respectively.

[1]  Leo Radom,et al.  Harmonic Vibrational Frequencies: An Evaluation of Hartree−Fock, Møller−Plesset, Quadratic Configuration Interaction, Density Functional Theory, and Semiempirical Scale Factors , 1996 .

[2]  E. T. Denisov,et al.  Estimation of the Bond Dissociation Energies from the Kinetic Characteristics of Liquid-Phase Radical Reactions , 2005 .

[3]  John A. Montgomery,et al.  A complete basis set model chemistry. VII. Use of the minimum population localization method , 2000 .

[4]  J. Bozzelli,et al.  Thermochemical properties of methyl-substituted cyclic alkyl ethers and radicals for oxiranes, oxetanes, and oxolanes: C-H bond dissociation enthalpy trends with ring size and ether site. , 2013, The journal of physical chemistry. A.

[5]  Martin Head-Gordon,et al.  Quadratic configuration interaction. A general technique for determining electron correlation energies , 1987 .

[6]  Kirk A. Peterson,et al.  Benchmark calculations with correlated molecular wave functions. IV. The classical barrier height of the H+H2→H2+H reaction , 1994 .

[7]  T. Dunning,et al.  Electron affinities of the first‐row atoms revisited. Systematic basis sets and wave functions , 1992 .

[8]  Hans-Heinrich Carstensen,et al.  Rate constants for the H abstraction from alkanes (R–H) by R′O2 radicals: A systematic study on the impact of R and R′ , 2007 .

[9]  E. T. Denisov,et al.  Estimation of dissociation energies of C—H bonds in oxygen-containing compounds from kinetic data for radical abstraction reactions , 2002 .

[10]  H. Curran,et al.  Rate constants for hydrogen abstraction by HȮ2 from n‐butanol , 2012 .

[11]  Parr,et al.  Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. , 1988, Physical review. B, Condensed matter.

[12]  B. Dlugogorski,et al.  Rate constants for reactions of ethylbenzene with hydroperoxyl radical , 2013 .

[13]  K. Laidler,et al.  Development of transition-state theory , 1983 .

[14]  G. Scuseria,et al.  Is coupled cluster singles and doubles (CCSD) more computationally intensive than quadratic configuration interaction (QCISD) , 1989 .

[15]  T. H. Dunning.  Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen , 1989 .

[16]  J. H. Jones,et al.  Chemicals from Hydrocarbons by Vapor Phase Oxidation , 1959 .

[17]  Kenneth S. Pitzer,et al.  Energy Levels and Thermodynamic Functions for Molecules with Internal Rotation I. Rigid Frame with Attached Tops , 1942 .

[18]  John M Simmie,et al.  Kinetics and thermochemistry of 2,5-dimethyltetrahydrofuran and related oxolanes: next next-generation biofuels. , 2012, The journal of physical chemistry. A.

[19]  Bogdan Z. Dlugogorski,et al.  Theoretical study of reactions of HO2 in low-temperature oxidation of benzene , 2010 .

[20]  David B. Krisiloff,et al.  Ab initio reaction kinetics of hydrogen abstraction from methyl formate by hydrogen, methyl, oxygen, hydroxyl, and hydroperoxy radicals. , 2012, The journal of physical chemistry. A.

[21]  Charles K. Westbrook,et al.  Chemical kinetics of hydrocarbon ignition in practical combustion systems , 2000 .

[22]  Angela K. Wilson,et al.  Gaussian basis sets for use in correlated molecular calculations. VI. Sextuple zeta correlation consistent basis sets for boron through neon , 1996 .

[23]  B. C. Garrett,et al.  Current status of transition-state theory , 1983 .

[24]  J. Yanowitz,et al.  Renewable Oxygenate Blending Effects on Gasoline Properties , 2011 .

[25]  Stefan Pischinger,et al.  Tailor-Made Fuels from Biomass for Homogeneous Low-Temperature Diesel Combustion , 2011 .

[26]  J. Heicklen,et al.  TUNNELLING CORRECTIONS FOR UNSYMMETRICAL ECKART POTENTIAL ENERGY BARRIERS , 1962 .

[27]  Weiran Yang,et al.  One-step catalytic transformation of carbohydrates and cellulosic biomass to 2,5-dimethyltetrahydrofuran for liquid fuels. , 2010, ChemSusChem.

[28]  G. A. Petersson,et al.  A complete basis set model chemistry. VI. Use of density functional geometries and frequencies , 1999 .

[29]  R. Bartlett,et al.  A full coupled‐cluster singles and doubles model: The inclusion of disconnected triples , 1982 .

[30]  G. A. Petersson.  Perspective on “The activated complex in chemical reactions” , 2000 .

[31]  Bogdan Z. Dlugogorski,et al.  Rate constants for hydrogen abstraction reactions by the hydroperoxyl radical from methanol, ethenol, acetaldehyde, toluene, and phenol , 2011, J. Comput. Chem..

[32]  Curtis L. Janssen,et al.  An efficient reformulation of the closed‐shell coupled cluster single and double excitation (CCSD) equations , 1988 .

[33]  A. Becke.  Density-functional thermochemistry. III. The role of exact exchange , 1993 .

[34]  John M Simmie,et al.  Accurate benchmark calculation of the reaction barrier height for hydrogen abstraction by the hydroperoxyl radical from methane. Implications for C(n)H(2n+2) where n = 2 --> 4. , 2008, The journal of physical chemistry. A.