Oxygen rearrangement on electron impact has been found to be an important fragmentation pathway in various (I-VII) cyclic ketones containing methoxyl and hydroxyl groups. This oxygen migration, which produces, for example, the m/e 60 ion (C2H4O2) from the molecular ion of 4-hydroxycyclohexanone (II), occurs in sixand seven-membered rings, with the two functional groups in both a 1,3 and 1,4 relationship. Heavy substitution around the ketone group appears to enhance the rearrangement while substitution adjacent to the hydroxyl or methoxyl group acts as a depressant. Deuterium labeling of 4-methoxy- and Δ5-hydroxycyclohexanone (I and II) suggested the intermediacy of the molecular ion of methyl As-hexenoate (XIII) in the case of 4-methoxycyclohexanone (I) and support for this proposal was provided by the synthesis of XIII. The rearrangement has been found to be unimportant in acyclic ketones containing primary methyl ether groups.
|Original language||English (US)|
|Number of pages||9|
|Journal||Journal of the American Chemical Society|
|State||Published - Sep 1 1967|
ASJC Scopus subject areas
- Colloid and Surface Chemistry