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purification?
indole_amine:
"yields tend to be completely irreproducible.
sometimes you'll get 60% from oiled out oxime, sometimes 10%. it's a bitch."
Maybe because the oxime is impure, always to a different degree? (that's why one should try and get it to crystallize - or at least distill it..)
And maybe different ketones give rise to different/more impurities upon oximation (or even during their production)?
(Just a thought! ;) )
indole_amine
POPTART:
Thanks bees, SWIM did some searching on oximes oiling out and SWIM will carefully read through these.
Adding too much water may make the oxime oil out. Well SWIM is happy to have kept everything. Some cleaning is due.
Will get back with more results.
a la prochaine...
POPTART:
Found some interesting information while using TFASE.
Post 356265 (Barium: "Oxime formation", Methods Discourse) and
Post 356287 (Chromic: "Clarifications on Sonson's method", Methods Discourse)
Will be tested out and come back with results.
hypo:
i don't know what barium's problem was, but it definitely works with
the usual ketones. maybe 2,5-DMP2P is different.
there's one minor point where i have to disagree with chromic:
> If the oxime doesn't crystallize overnight, it ain't gunna...
full crystallisation can take 1-2 weeks, starting at day 2-3!
ps: you should note success by smell: the oxime, even when oiled out, has
that characteristic amine/oxime smell as opposed to the flowery ketone smell.
you can't mistake the two.
indole_amine: what are the boiling points of our oximes? distilling solids
can be quite annoying (if you don't have a short-path distillation thingie).
indole_amine:
Many things solidify/crystallize in the freezer, but can be distilled without any difficulties. Think of GAA!
I would guess that the oxime bp lies somewhere between the boiling points of the ketone and the amine... :P
(I don't remember the bp anymore; but I once vac distilled P2P oxime, years ago)
indole_amine
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