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Author(s):   Safont, V.S.; Andres, J.; Castillo, R.; Chuchani, G.; Rotinov, A.; Dominguez, R.M.; Herize, A.
Title:   A joint experimental and theoretical study on the mechanisms of methyl 2-hydroxypropionate and methyl 2-hydroxyisobutyrate decomposition in the gas phase
Journal:   J. Phys. Chem. A
Volume:   108
Page(s):   996 - 1007
Year:   2004
Reference type:   Journal article
Squib:   2004SAF/AND996-1007

Reaction:   (CH3)2C(OH)C(O)OCH3CH3OH + Acetone + CO
Reaction order:   1
Temperature:   653 - 713 K
Pressure:  9.33E-2 - 0.28 bar
Rate expression:   2.34x1013 [s-1] e-217500 [±5100 J/mole]/RT
Uncertainty:   2.53999996
Category:  Experiment
Data type:   Absolute value measured directly
Pressure dependence:   None reported
Experimental procedure:   Static or low flow - Data taken vs time
Excitation technique:   Thermal
Time resolution:   By end product analysis
Analytical technique:   Gas chromatography
Comments:   Combined experimental and computational study. Measured decomposition of hydroxesters in a static reactor seasoned with allyl bromide and using cyclohexene or toluene as a radical inhibitor. Also tested for heterogeneous reactions by packing reactor.

Used ab initio MP2 and B3LYP DFT quantum calculations with 6-31G** and 6-31++G** to elucidate reaction mechanism and energetics. Ab initio calculations gave same barriers within about 10 kJ/mol and A factors within about factor of 3.

Combined experimental and computations point toward a concerted reaction involving 5 membered cyclic transition state for elimination of aldehyde plus CH3OH plus CO. Other elimination channels are energetically unfavorable and few byproducts observed experimentally.

View full bibliographic record.

Rate constant values calculated from the Arrhenius expression:

T (K)k(T) [s-1]
653 9.45E-5
675 3.45E-4
700 1.38E-3
713 2.75E-3