Bending Force Constants for Halogenated Ethylenes

Pitzer, Kenneth S.; Freeman, N. K.

doi:10.1063/1.1724069

Cited by 54 publications

(57 citation statements)

References 11 publications

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“…General features of the transition state theory method have been described elsewhere. Details specific to reaction 3 are given in the Appendix in the supporting information. − The three parameters V b , T *, and ω b , in eq 16 were fitted to the experimental data by nonlinear least squares . The parameters were found to be equal to 46.0 ± 1.0 kJ mol -1 , 375 ± 17 K, and 279 ± 8 cm -1 , respectively.…”

Section: Discussionmentioning

confidence: 99%

Initiation and Abstraction Reactions in the Pyrolysis of Acetone

Mousavipour

Pacey

1996

J. Phys. Chem.

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The rates of the reactions, (CH3)2CO → CH3 + CH3CO (1) and CH3 + (CH3)2CO → CH4 + CH2COCH3 (3) have been studied in the flow pyrolysis of acetone at 825−940 K and 10−180 Torr. Yields of products were measured by gas chromatography. The rate constant, k 1, for the initiation reaction, determined from the sum of the yields of the termination products, was observed to be pressure dependent at 928 K. The Arrhenius expression for this reaction at the high-pressure limit (obtained from a nonlinear least-squares fit to the experimental data using the Troe factorization procedure) was found to be k 1 ∞ (s-1) = 1017.9±0.8 exp(−353 ± 14 kJ mol-1/RT). The Troe method has also been used to find the high-pressure limits of the cross-combination ratio for CH3 and CH3COCH2 radicals (1.9 ± 0.1) and of the quotient k 5/k 3 2, where reaction 5 is 2CH3 → C2H6. Calculated rate constants for reaction 3, when combined with values reported from photolysis experiments at lower temperatures, were found to exhibit a curved Arrhenius plot. A transition state theory model was fitted to the data for k 3 to determine the average transitional vibrational term value in the transition state (279 ± 8 cm-1), the effective activation barrier height (46 ± 1 kJ mol-1), and the full width of the barrier at half its height (52 ± 3 pm).

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Section: Discussionmentioning

confidence: 99%

Initiation and Abstraction Reactions in the Pyrolysis of Acetone

Mousavipour

Pacey

1996

J. Phys. Chem.

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“…Hydrogen bond dissociation groups developed by Lay et al are used to calculate thermodynamic properties of the respective radicals. S ° 298 and C p °( T ) (300 ≤ T / K ≤ 1500) of transition states species in the unimolecular reactions are calculated by MOPAC6/PM3, , where internal rotor contributions to entropies and heat capacities are included by the method of Pitzer and Gwinn. − …”

Section: Methodsmentioning

confidence: 99%

“…18 frequencies based on the optimized B3LYP/6-31G(d,p) structure are 243.2103, 265.2100, 314.4401, 424.8357, 447.7203, 507.8623, 667.9922, 939.0599, 1072.1868, 1163.2286, 1234.8179, 1299.7676, 1436.5185, 1507.6935, 3114.2617, 3188.9373, 3307.0414, and 3810.6613 cm -1 . g MOPAC6/PM3 plus contributions from internal rotors calculated by Pitzer and Gwinn's method. − h Enthalpies of TS calculated by MOPAC6/PM3 are not used in the rate constant calculations, only shown here as references. For reaction barriers, see Figure a,b and Table .…”

Section: Methodsmentioning

confidence: 99%

Reaction of OH Radical with C₂H₃Cl: Rate Constant and Reaction Pathway Analysis

Zhu

Bozzelli

1999

J. Phys. Chem. A

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There are two different carbon sites in C2H3Cl where OH addition or abstraction reactions can occur, α and β to the Cl atom, with several dissociation and isomerization products of each addition adduct. Thirteen elementary reactions and 18 species are included in the analysis of this reaction system. Thermochemical kinetic parameters are developed for each elementary reaction process. Chemical activation kinetic analysis with multifrequency QRRK theory for k(E) and master equation for falloff are used to estimate overall rate constants as functions of temperature and pressure. Thermodynamic parameters, including ΔH f°298, S°298, and C p°(T) (300 ≤ T/K ≤ 1500), of stable species are from the literature when available or estimated by the group additivity method. Values for CHClOHĊH2 are determined by density functional calculation and isodesmic reactions. Results are compared with the experimental data. Rate constants (300∼2000 K, in cm3 mol-1 s-1, E a in cal/mol) for the important addition and abstraction channels at 760 Torr are as follows: k = 1.22 × 1084 T -25.5 exp(−15000/RT) for C2H3Cl + OH → CHClOHĊH2; k = 1.77 × 1040 T -9.08 exp(−7240/RT) for C2H3Cl + OH → ĊHClCH2OH; k = 9.72 × 106 T 2 exp(−3800/RT) for C2H3Cl + OH → CH2ĊCl + H2O; k = 1.69 × 107 T 2 exp(−4390/RT) for C2H3Cl + OH → ĊHCHCl + H2O.

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“…The ab initio geometry of ref was used to calculate the optional value shown in parentheses. The moment of inertia for internal rotation for reaction 1 was calculated following the method of Pitzer …”

Section: Input Parametersmentioning

confidence: 99%

Properties of Transition Species in the Reactions of Hydroxyl with Ammonia and with Itself

1996

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Quantum transition state theory was used to model two hydrogen atom abstraction reactions of hydroxyl radicals. Moments of inertia for the transition species were calculated from geometries obtained by ab initio or bond energy bond order methods. The transition state equation was fit by nonlinear least squares to experimental rate constants to determine parameters of the transition species. For the reaction of hydroxyl with ammonia, the geometric mean, ω b , of four transitional vibrational frequencies was found to be 660 ( 20 cm -1 , the activation barrier height, V b , including zero point energy, to be 8.5 ( 0.5 kJ mol -1 , and the barrier thickness, at half its height, to be 65 ( 30 pm. For the disproportionation reaction of hydroxyl radicals, the corresponding values of the first two parameters, based on the most recent experimental data, were 890 ( 20 cm -1 and 2.7 ( 0.8 kJ mol -1 . Ab initio calculations on the latter reaction gave ω b ) 746 cm -1 at the HF/6-31G(d,p) level and V b ) 13.6 kJ mol -1 at the MP4/6-311G(d,p) level. The curvature of the Arrhenius plots can be explained by the contributions of the low-frequency vibrations and, for the disproportionation reaction, of the low-lying electronic states.

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Bending Force Constants for Halogenated Ethylenes

Cited by 54 publications

References 11 publications

Initiation and Abstraction Reactions in the Pyrolysis of Acetone

Initiation and Abstraction Reactions in the Pyrolysis of Acetone

Reaction of OH Radical with C₂H₃Cl: Rate Constant and Reaction Pathway Analysis

Properties of Transition Species in the Reactions of Hydroxyl with Ammonia and with Itself

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Bending Force Constants for Halogenated Ethylenes

Cited by 54 publications

References 11 publications

Initiation and Abstraction Reactions in the Pyrolysis of Acetone

Initiation and Abstraction Reactions in the Pyrolysis of Acetone

Reaction of OH Radical with C2H3Cl: Rate Constant and Reaction Pathway Analysis

Properties of Transition Species in the Reactions of Hydroxyl with Ammonia and with Itself

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Product

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Reaction of OH Radical with C₂H₃Cl: Rate Constant and Reaction Pathway Analysis