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Author(s):   Jorge, N.L.; Romero, J.M.; Grand, A.; Hernandez-Laguna, A.
Title:   Gas-phase thermolysis reaction of formaldehyde diperoxide. Kinetic study and theoretical mechanisms
Journal:   Chem. Phys.
Volume:   393
Page(s):   37 - 45
Year:   2012
Book Title:   ''
Editor:   ''
Publisher:   ''
Publisher address:   ''
Comments:   ''
Reference type:   Journal article
Squib:   2012JOR/ROM37-45

Reaction:   1,2,4,5-tetroxane → CH2O + CH2O + O2
Reaction order:   1
Temperature:   463 - 503 K
Pressure:  1.01 bar
Rate expression:   3.3x1013 [s-1] e-112550 [J/mole]/RT
Category:  Theory
Data type:   Transition state theory
Pressure dependence:   Rate constant is high pressure limit
Comments:   Reaction potential energy surface was studied using quantum chemistry and product channels were analyzed. The tetroxane decomposition was initiated at the singlet state by O–O bond homolitic breakdown (activation energy 16.1 kcal/mol), then the decomposition might proceed with two different pathways: either (i) on the singlet state PES; or (ii) the triplet state PES. If the reaction proceeded to the singlet state, the activation energy of the first and seconds step were 29.9 kcal/mol, and 13.9 kcal/mol, respectively. If the reaction proceed for the triplet state, the activation energy of premier step was 25.8 kcal/mol, and last step was 9.6 kcal/mol. A non-adiabatic transition from the singlet to the triple state PES occurred at the diradical open structure, due to a spin–orbit coupling between the two states, which went through a clearly exothermic reaction, yielding two formaldehyde molecules and one oxygen (triplet state) as products.

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Rate constant values calculated from the Arrhenius expression:

T (K)k(T) [s-1]
463 6.62E0
475 1.39E1
500 5.76E1
503 6.77E1