The eliminations of methanol (CH
3OH) and formaldehyde (CH
2O) molecules from the molecular ion of 1,2-dimethoxyethane have been investigated by using deuterium labelling technique and mass analyzed ion kinetic energy (MIKE) spectra. The MIKE spectra show that the structure of the resultant ion at
m/z 58, [M-CH
3OH]
+., is identical with that of the molecular ion of methyl vinyl ether ([CH
3OCH=CH
2]
+.), and that of the ion at
m/z 60, [M-CH
2O]
+., is an oxonium type ion, [CH
3O(H)CH
2CH
2.)]
+. The hydrogen rearrangements associated with these reactions result in thermochemical stabilization in the product systems. The loss of CH
3OH molecule is accompanied by a kinetic energy release (T
0.5 = 101 meV) larger than that in the elimination of CH
2O molecule (T
0.5=17 meV). A significant isotope effect is observed in the methanol and formaldehyde losses from deuterated 1,2-dimethoxyethane CH
3OCH
2CD
2OCD
3 (2,5-dioxahexane-1,1,1,3,3-d
5). These results are discussed along with mechanistic features of both reactions.
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