Electronic Resource
College Park, Md.
:
American Institute of Physics (AIP)
The Journal of Chemical Physics
87 (1987), S. 4589-4597
ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Fragmentation mechanisms of the methyl formate and methyl formate-d1 ions have been investigated using threshold photoelectron–photoion coincidence (TPEPICO) mass spectrometry. The breakdown diagrams and ion kinetic energies of fragment ions were measured at internal energies of the molecular ion from 0 to 7 eV, and fragmentation pathways were elucidated. The formation of HCO+ showed a large kinetic isotope effect. The formation of CH3O+ from methyl formate-d1 is accompanied by a large kinetic energy release, about twice that calculated using quasiequilibrium theory (QET). Its relative abundance in the breakdown curve also appears to be inconsistent with statistical theory. Direct dissociation from an isolated state of the molecular ion was one possible explanation. Slow dissociations were observed for the formation of methanol ions resulting from a migration of the formyl hydrogen while QET predicts no metastable dissociation for this process. Two-component reaction rates for methanol ion formation suggest participation of more than one state or isomer. The heat of formation of HCOO was found to be −40±6 kcal/mol, indicating that it is less stable than COOH (ΔHf =−58+4 kcal/mol).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.452870
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