swim's first oximation dream ended up with a green jellyfish blob that he couldn't do anything with.

swim changed some parameters and then he got an aldoxime that was white (with a hint of yellow) and very sticky/tacky.  need it to solidify to the point where its no longer sticky because of all the mechanical losses of it sticking to everything.  washed it several times with water but it refused to solidify (it's insoluble in water).  it would become immobilized/solidify in the freezer but upon thawing out would return to the same consistency as before.  swim saw that covering it in 70% IPA (it is insoluble in water but slightly soluble in IPA) allowed it to solidify to something that looked like cottage cheese except perhaps a little more stringy looking, not crystalline but definitely a solid and no longer sticky, it was clumpy as in it clumped to itself like cottage cheese in appearance but it wasn't sticky so no mechanical losses to the surface of things it touches.  a little more H2O was added to the IPA to dilute it more and decrease solubility of the aldoxime in the IPA.  the IPA was then removed whatever impurity was keeping the oxime sticky.  the IPA was pipetted off and kept in a separate beaker, then the oxime was put under a fan to dry out.  the IPA in the beaker was yellowish orangeish and the oxime was off-white.

as the oxime dried under the fan it began to turn dark, a dark green in fact.... weird.  the IPA, over the course of a day, began to clear up to a light milky white/yellow color and on the bottom of the beaker was a nasty dark orange viscus oil.  why an off-white cottage-cheese-solid aldoxime turned dark green when being dried over a fan swim has no idea

swim wasn't sure just how much oxime was lost (dissolved) in the IPA so he poured the beaker with the IPA and viscus oil back onto the oxime to start from scratch again.  would a method like recrystallization help purify this oxime?  the oxime is fairly soluble to warm MeOH and a little less soluble in IPA he thinks (he assumes this from some very crude, quick tests the other day), adding water helps push the oxime out however it seems to be easier to precipitate the oxime out of IPA than MeOH, he may be wrong as that is what he's assuming from a quick test.

he's thinking of trying crystallization using hot alcohol (IPA or MeOH) but read of a different oxime being recrystallized from hexane.  swim doesn't have hexane but he has heptane he can try (h**p://www.erowid.org/archive/rhodium/chemistry/alpha-deuterio.amphetamine.html)

swim has been trying to get it to solidify as a white solid (is it crystalline in its purest form?) at room temp without much success

classic oiling out problems can be remdied by forming the water soluble protonated salts dissolving in water (minimal for maximum partition action)
then you can precede to wash with different solvents this would be expirimentally done and based on order or polarity i dare say chlorinated solvents may work but then you might get the oxime salt in the org phase.

Bullshit, the aldoxime does not get protonated. The acidic treatment neutralizes remaining alkaline water impurities trapped in the oily layer of the aldoxime and therefore allowing it to crystallize.

Oximes do not have the same basic/nucleophilic properties like amines or imines. The inductive effect on that N-O bond delocalize the electron cloud around the nitrogen atom and decrease its possibility to act as a base.

In this case where upon a very mild acidification is required to separate the phases properly. Alkaline compounds generally have soapy qualities (especially the NaOH usually imployed) and can have a detergent like effect forming micelles and keeping the oxime wet. So bubbling CO2 ect through can remove those qualities, allowing the oxime to dry!

@NPH, are you aware that green jelly fish is pure oxime! and good to go. As in, decant the water off, add more and repeat until clean, pour in some non-polar stir until the jellyfish is gone, and the non-polar is now green separate and wash if you need it dry treat with some magnesium sulfate. Filter and use as it is pure and works well in further syntheses, I have had this problem several times the most recently with benzaldehyde (but was not a green oxime ). A quote that I have passed around a bit;

Oximation of benzaldehyde; syn-Benzaldoxime
SyntheticPage 160 (SP160)

"Product obtained as a colourless liquid; reported to be a solid.
The liquid is pure, and worked well in further reactions. Scratching and trituration failed to get crystalline product. The bubbling of CO2 through the aqueous mixture is presumably just a mild acidification, (forming carbonic acid) to effect the separation of the oil from the aqueous layer. Other arylaldoximes were prepared by similar methods, however the solvents the reactions were performed in, and other aspects of the procedures, were slightly different, and will be described on other synthetic pages"

http://cssp.chemspider.com/Article.aspx?id=160

And as QD said that oxime is definitely not protonated by that mild acidification! If it was it would no longer be an oxime!!!

5% acetic added to the liquid oxime seems to clear things up for me during crystalization. It's about the only thing I've found to work if water washes fail to form a solid. Other weak, dilute acids work as well, at least for me.

not much progress unfortunately, i think i may be dealing with an aldoxime that is slightly more impure than your guys maybe.  i'm really dead set on trying to get this thing to solidify and as white as possible, like madpro's aldoxime.

IPA:
so i put enough anhydrous IPA to cover the aldoxime in the dish and swirled around for a few minutes, the IPA went cloudy white and left behind some nasty looking green aldoxime that did look less gooey and more solid.  decanted off the white IPA into a small beaker and set that aside.  the particulate in the IPA is so fine it just seems like cloudy white, i don't think it would filter well

MeOH:
used just enough MeOH to cover the nasty aldoxime left behind after the IPA wash above, it began to dissolve the aldoxime which started to brighten up really nicely.  the MeOH began to turn an orangeish color leaving cottage cheese-looking crumbly off-white aldoxime behind.  you could see the MeOH break off white solids away from the greenish piece leaving behind what looked like a viscus oil which it eventually penetrated but took awhile.  the viscus oil dissolved into the meoh altogether leaving the off-white aldoxime floating around.  there was some aldoxime suspended in the MeOH but you could see the particulate and was large enough to filter off.  so the MeOH was decanted off the dish and gravity filtered.  the filter cake was a white paste and the filtrate was a nasty orangeish color with a hint of green that just made it look like a dirtier darker orange.  took the filter cake and put it back on the pyrex dish alongside the rest of the off-white aldoxime that decided to stay put and not be suspended in the MeOH.  put the dish in front of a fan to dry it out.  as of now it is not a solid that can be crushed up yet so we'll see how it goes as it dries out

covered the IPA beaker and MeOH beaker and put them both in the freezer to see what happens.  in the future would probably want to use ice cold alcohols instead of room temp.  am curious to see what (if anything) precipitates out of the beakers.  if nothing precipitates then i'm particularly curious to see what's in the cloudy white IPA and may pour it into a dish and evaporate it to see what's left behind.  i'm pretty sure the MeOH, if evaporated, would leave behind some nasty oily crap

has anyone used alcohols in this manner as part of the work-up yet?  it's too early for me to say anything one way or another just yet but it seems quite effective as long as too much aldoxime isn't dissolved into the alcohols

another idea if this works out ok would be to use hot MeOH to dissolve the aldoxime, impurities and all then freeze precipitate the pure aldoxime and filter.  then perhaps dilute the MeOH with a lot of water and see what happens, if it pushes out more aldoxime or if it just pushes out some impure oil

Quote from: NeilPatrickHarris on May 19, 2010, 12:23:36 AM

not much progress unfortunately, i think i may be dealing with an aldoxime that is slightly more impure than your guys maybe.  i'm really dead set on trying to get this thing to solidify and as white as possible, like madpro's aldoxime.

swirl and scratch the aldoxime with a spoon. It will induce crystallization. Try to put the plate in the freezer for 10-20 mins. Usually my aldoxime solidify after 20-25 minutes after the acidic wash. Be patient.

If theres still no solid, im pretty sure woure reaction was incomplete and you have a fair deal of unreacted carbonyl oil in there. Just a hunch though.

QD

i think you may be right about unreacted oil in there because earlier in my "tinkering around" with this i managed to wash oil out of the aldoxime with IPA leaving a fairly nice off-white solid, that IPA was left undisturbed for a day and a nasty viscus oil fell to the bottom.

thanks for all the tips.  i'm probably going to get it as good as possible with alcohol washes this time around then next time i'll wash the oxime x2 h2o to remove meoh/h2o from the reaction solution, then go immediately to the acetic acid washes, then x2 h2o to remove base salts and residual acetic acid.  then i'll put it in the freezer and see how it goes

Pour it into a pyrex as a thin layer, put in the freezer overnight, come back and scratch the shit out of it with a fork.  Leave it in the freezer for a week, checking every day to see when it crystallized.  Even if it solidifies after 4 days it should still be pure enough for the next step.  Just use it while its a liquid, makes charging flasks easier.  I would really make sure the next step works even if you can't get it to solidify.  pm me for troubleshooting