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Author(s):   Johnson, D.; Cassanelli, P.; Cox, R.A.
Title:   Correlation-type structure activity relationships for the kinetics of the decomposition of simple and beta-substituted alkoxyl radicals
Journal:   Atmos. Environ.
Volume:   38
Page(s):   1755 - 1765
Year:   2004
Reference type:   Journal article
Squib:   2004JOH/CAS1755-1765

Reaction:   C2H5C(CH3)2O(·) → (CH3)2CO + ·C2H5
Reaction order:   1
Temperature:   190 - 330 K
Pressure:  1.01 bar
Rate expression:   1.0x1013 [s-1] e-47700 [J/mole]/RT
Category:  Theory
Data type:   Estimated: thermochemical, kinetic, or other
Comments:   The authors developed a structure activity relationship (SARs) for the estimation of rate data for the decomposition of RO to alkyl radical and carbonyl fragments. The SARs are based upon strong, non-linear, correlations between the logarithm of measured room temperature rate coefficients and the average measured ionisation potential (IP) of the reaction products,. The considered compounds include simple unsubstituted, beta-chlorinated and beta-hydroxylated alkoxylradicals. Chemical activation processes in the decomposition chemistry are briefly discussed.

The temperature range over which the estimates are intended to be useful is not specifically given, but the results are derived for atmospheric chemistry occurring in the troposphere through lower stratosphere. This is assumed by us to approimately cover 190 K to 330 K.

For the 10 simple and 11 heteroatom-substituted RO: species used to construct the correlations, 18(85%) of the room temperature rate coefficients predicted using the present method are within a factor of two of their measured (or theoretically calculated) values, and 100% are within a factor ofthree. The average ratio of measured to calculated rate coefficients is 0.9.

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Rate constant values calculated from the Arrhenius expression:

T (K)k(T) [s-1]
190 7.70E-1
200 3.49E0
225 8.44E1
250 1.08E3
275 8.71E3
300 4.95E4
325 2.16E5
330 2.82E5