OH + CH3 -> CH2(S) + H2O

k = 2.50E+13 cm3/mol s

SOURCE:

The parameters represent the results of a 4-channel RRKM calculation, which were fit to the methanol decomposition data of Spindler et al. (1982), Dombrowsky et al. (1991), and Cribb et al. (1984), and the room temperature data for OH + CH3 of Hughes et al. (1992) and Anastasi et al. (1991). Parameters for channels 3 and 4 are estimates.

The initial value is a result of a 4-channel RRKM calculation, which were fit to the decomposition data of Spindler et al. (1982), Dombrowsky et al. (1991), and Cribb et al. (1984), and the high-pressure room-temperature data of Hughes et al. (1992) and Anastasi et al. (1991).

The choice for the rate coefficient is a compromise fit to the conflicting low pressure data of Hughes et al. (1992), Hack et al. (1988), Staker et al. (1975), which favor a higher value, and of Oser et al. (1992) and Bott and Cohen (1991) (at 1200 K) which favor a lower value.

The 4 reactions channels are:

Channel	Reaction	Reaction Number
1	CH2(S) + H2O (+M) = CH3OH (+M)	147
2	OH + CH3 (+M) = CH3OH (+M)	95
3	H + CH2OH (+M) = CH3OH (+M)	59
4	H + CH3O (+M) = CH3OH (+M)	63

Related chemical activation reactions:
61. H + CH2OH -> OH + CH3
62. H + CH2OH -> CH2(S) + H2O
64. H + CH3O -> H + CH2OH
66. H + CH3O -> OH + CH3
67. H + CH3O -> CH2(S) + H2O

Rate coefficients computed by 4-channel RRKM calculation.
<delta-E> = 0.30 kcal/mol
The Lennard-Jones parameters: sigma(CH3OH-N2) = 3.70 A, epsilon = 270 K
Active molecular K-rotor 4.11 amu-A^2, sigma = 1
Torsion 0.705 amu-A^2, sigma = 3
Adiabatic I = 18.8 amu-A^2, sigma = 1
v = 3680, 3000, 2960, 2840, 1480, 1480, 1450, 1350, 1160, 1060, 1030 cm^(-1)

Transition state 1 CH2(S) + H2O
delta-E(0 K) = 0.0 kcal/mol; delta-H(0 K) = -89.96 kcal/mol
Adiabatic I+ = 75.2 amu-A^2 at 1200 K (113 at 400 K), sigma = 1
(These values relative to the molecule are used for the Waage-Rabinovitch factor.)
v = 3760, 3660, 3070, 3020, 1600, 1400 cm^(-1)
Active 1-D rotors I = 2.13, 0.53 amu-A^2; sigma = 2,2
2-D hindered rotors I = 0.37, 0.28 amu-A^2 (96%) at 1200 K [0.53, 0.40 at 400 K (92%)]; sigma = 1,1

Transition state 2 OH + CH3
delta-E(0 K) = 0.0 kcal/mol; delta-H(0 K) = -90.48 kcal/mol
Adiabatic I+ = 122 amu-A^2 at 1200 K (160 at 400 K), sigma = 1
v = 3570, 3180, 3180, 3000, 1380, 1380, 580 cm^(-1)
Active 1-D rotor I = 4.11 amu-A^2, sigma = 1
2-D hindered rotors I = 0.70, 0.30 amu-A^2 (90%) at 1200 K [0.83, 0.36 at 400 K (86%)]; sigma = 1,1

Transition state 3 H + CH2OH
delta-E(0 K) = 0.0 kcal/mol; delta-H(0 K) = -97.3 kcal/mol
adiabatic I+ = 18.8 amu-A^2, sigma = 1
v = 3640, 3000, 3000, 1460, 1330, 1180, 1050, 950, 290 cm^(-1)
Active 1-D rotor I = 4.11 amu-A^2, sigma = 1
2-D hindered rotor I = 1.87 amu-A^2 (90%), sigma = 1

Transition state 4 H + CH3O
delta-E(0 K) = 0.0 kcal/mol; delta-H(0 K) = -102.7 kcal/mol
Adiabatic I+ = 18.8 amu-A^2, sigma = 1
v = 3320, 3320, 3220, 1660, 1600, 1580, 1160, 1060, 720 cm^(-1)
Active 1-D rotor I = 4.11 amu-A^2, sigma = 1
2-D hindered rotor I = 0.46 amu-A^2 (90%), sigma = 1

COMMENTS:

The channel 1 parameters reflect a compromise fit to the conflicting low pressure 300 K data for reaction
97. OH + CH3 -> CH2(S) + H2O.
Hughes et al. (1992), Hack et al. (1988), and Staker et al. (1991) favor a higher value, and Oser et al. (1992) and Bott and Cohen (1991) (at 1200 K) favor a lower value. The channel 2 parameters were selected to match the high pressure 300 K data of Hughes et al. (1992) and Anastasi et al. (1991) and the decomposition data of Spindler et al. (1982), Dombrowsky et al. (1991), and Cribb et al. (1984).

Results for methanol decomposition, k_o in Ar at 1800 K

Reference	cm3/mol s
GRI-Mech	8.3E8
Cribb et al. (1984)	5.4E8
Spindler et al. (1982)	1.0E9
Hidaka et al. (1989)	3.2E8

Spindler et al. (1982): Spindler, K., and Wagner, H.G. (1982) Ber. Bunsenges. Phys. Chem. 86, 2.
Dombrowsky et al. (1991): Dombrowsky, C., Hoffmann, A., Klatt, M., and Wagner, H. Gg. (1991) Ber. Bunsenges. Phys. Chem. 95, 1685.
Cribb et al. (1984): Cribb, P.H., Dove, J.E., and Yamazaki, S. (1984) 20th Symposium (International) on Combustion, p. 779.
Hughes et al. (1992): Hughes, K.J., Pereira, A.R., and Pilling, M.J. (1992) Ber. Bunsenges. Phys. Chem. 96, 1352.
Hack et al. (1988): Hack, W., Wagner, H.Gg., and Wilms, A. (1988) Ber. Bunsenges. Phys. Chem. 92, 620.
Staker et al. (1991): Staker, W.S., King, K.D., Gutsche, G.J., and Lawrence, W.D. (1991) J. Chem. Soc. Farad. Trans. 87, 2421.
Oser et al. (1992): Oser, H., Stothard, N.D., Humpfer, R., and Grotheer, H.H. (1992) J. Phys. Chem. 96, 5359.
Bott and Cohen (1991): Bott, J.F., and Cohen, N. (1991) Int. J. Chem. Kinet. 23, 1017.
Anastasi et al. (1991): Anastasi, C., Beverton, S., Ellermann, T., and Pagsberg, P. (1991) J. Chem. Soc. Farad. Trans. 87, 2325.
Hidaka et al. (1989): Hidaka, Y., Oki, T., Kawano, H., and Higashihara, T. (1989) J. Phys. Chem. 93, 7134.

______________________________________________________________________
    Temp      delta-S     delta-H      kf          kr         Keq
     (K)    (cal/mol K)  (kcal/mol) ----(mol,cm3,s)-----   
______________________________________________________________________

     300          .1          .4    2.50E+13    5.00E+13    5.00E-01
     500         -.2          .3    2.50E+13    3.82E+13    6.54E-01
    1000         -.8         -.1    2.50E+13    3.51E+13    7.12E-01
    1500        -1.2         -.6    2.50E+13    3.71E+13    6.74E-01
    2000        -1.5        -1.1    2.50E+13    3.97E+13    6.29E-01
    2500        -1.6        -1.5    2.50E+13    4.23E+13    5.90E-01
    3000        -1.8        -1.8    2.50E+13    4.48E+13    5.59E-01
______________________________________________________________________

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