6.11.2 Fragmentation of Cyclic Ketones

Cyclic ketones major cleavage is also at the α bond.  Due to the ring structure, this cleavage will be detected as the molecular ion unless another bond is broken.  Saturated cyclic ketones produce a fragment at m/z 55 illustrated by cyclohexanone.

In cyclohexanone, this peak is the base peak.  In absence of a reference standard, cyclic ketones are difficult to identify given the difficulty explained earlier in determining the composition of the alkyl portion of the ketone.

©Dunnivant & Ginsbach, 2008