Acetophenone oxime isomerism

We will look at three pairs of syn and anti aldoxime isomers, 9A and 9B, corresponding to R = CH3 (acetaldoxime), R = CH2CI (chloroacetaldoxime) and R = CgH5 (benzal-doxime). We will also consider the two isomeric forms lOA and lOB of acetophenone oxime, a ketoxime in which R = CH3 and R" = CeHs. 

Oxaziridines are accepted as intermediates in the photorearrangements of oximes to amides and lactams. The formation of host-guest complexes in acetophenone oxime derivatives that incorporate a crown ether moiety has been shown to stimulate triplet-derived Z-J -isomerization and to depress singlet-derived oxaziridine formation. Low yields of lactams (115>—(117) have been obtained on irradiation of D-nor-5a-androstan-16-one oxime (118) in methanol. The unusual formation of lactam (117), in which the chirality of the... 

The three isomeric acetopyridine oxime tosylates, intermediates in an Organic Syntheses procedure wherein they are thermally rearranged, were found to have heats of decomposition around 1 kJ/g, enough to present a serious hazard if the reaction be conducted much beyond the decagram scale. Onset of decomposition is quite sudden at around 80°C. They are also marginally shock sensitive. The acetophenone homologue has a much lower heat of decomposition around 0.4 kJ/g. 

Ketones which contain two very dissimilar radicals, such as acetophenone, C6H6.CO.CH3, do not yield isomeric oximes. 

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