Strong oxidizing agents (like KMnO
4, CrO
3) are able to oxidize ketones. The reaction is only of synthetic use for cyclic ketones (to generate terminal aliphatic di-carboxylic acids), since oxidation of aliphatic ketones generates a hopeless mixture of compounds (destructive oxidation).
If one carefully titrates, I don't think there will be any problem, because benzaldehyde is a far better reductant than P2P. If you want to play it safe, choose a milder oxidizing agent.
Probably the best idea is to form the bisulfite adduct, like Barium said.
I remember from developing a sprayed TLC in a chlorine atmosphere (KMnO
4 / HCl) that it ruined the beaker pretty much ...
, damned MnO
2.
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