Author Topic: purification?  (Read 2592 times)

0 Members and 1 Guest are viewing this topic.

indole_amine

  • Guest
purification?
« on: November 07, 2004, 07:32:00 AM »
"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

  • Guest
reading to do
« Reply #1 on: November 08, 2004, 07:31:00 AM »
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

  • Guest
Found some interesting information while using
« Reply #2 on: November 10, 2004, 06:29:00 AM »
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

  • Guest
clarification of the clarification ;)
« Reply #3 on: November 10, 2004, 07:01:00 AM »
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

  • Guest
purification clarification... ;^)
« Reply #4 on: November 11, 2004, 07:45:00 AM »
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

hypo

  • Guest
so...
« Reply #5 on: November 12, 2004, 02:50:00 AM »
...did anybody ever distill substituted P2P-oximes? was it worth the hassle/losses?
(i don't care about P2P-oxime since it's probably more or less indestructible, just like P2P)