ISSN:
0947-6539
Keywords:
ab initio calculations
;
dimethyl peroxide
;
mass spectrometry
;
peroxides
;
radical ions
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The structure and the unimolecular fragmentations of the metastable dimethyl peroxide radical cation have been investigated by mass spectrometric and isotopic labeling methods as well as high-level ab initio calculations. In line with the theoretical results, neutralization-reionization and charge reversal experiments suggest that ionized dimethyl peroxide bears a CH3OOCH•3 connectivity. In the cation the O-O bond dissociation energy is larger than that of the neutral counterpart; in contrast, the C-O bond strength is slightly and that of the C-H bond significantly reduced upon ionization. These energetic changes upon one-electron oxidation of CH3OOCH3 are also reflected in the NR and CR mass spectra of CH3OOCH•+3. Further, for metastable CH3OOCH•3 two major fragmentation pathways are observed: 1) Loss of a hydrogen atom by cleavage of a C-H bond is associated with a skeletal reorganization, which gives rise to a proton-bound formaldehyde dimer. 2) The expulsion of a CH3O• radical leads to protonated formaldehyde in a surprisingly specific double hydrogen transfer involving a [CH3OH/CH2O]• ion/dipole complex as central intermediate; this complex also accounts for other minor fragmentation channels. The structures of intermediates and transition states are calculated with the BECKE 3LYP density-functional method employing a 6-311++G** basis.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/chem.19970030420
