Author Topic: After gassing, solution turned...blue.  (Read 778 times)

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Daphuk_up

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After gassing, solution turned...blue.
« on: February 11, 2004, 06:09:00 AM »
SWID was playing around again (he never seems to stop), this time with nitropropenes.  He apparently synthed the psuedonitrosite from undistilled calamus oil using Bruckners method.  In the past he had attempted several times the same reaction but using iron wool and nitric acid, ala pugsley, but out of the two times only succeeded once with a whopping 11% molar yield.

Using Bruckners method, and not quite all the sulfuric dripped in, he was able to achieve 55% yield after treatment with HCl and filtering.  Probably would have gotten a lot better, as he was tired, filtered only once and disposed of the mother liquor.

Anyways, SWID was ecstatic, and proceeded once again to look into Urushibara catalysts as a means of both reducing the double bond and changing the nitro to an amine.

SWID went with UNi-ZnB(s) due to ease of prep, and the process seemed to proceeded as planned over a 36 hour peroid wherein the voraciously stirred mixture absorbed ~3-4L of H2 gas (produced by the action of HCl(aq) on Al foil in a seperate flask and piped in).

Subsequent work-up showed quite a bit of unreacted material, but a fair bit ended up in the water layer after acidification.  Unfortunately, SWID (as he is so prone to do) did something stupid, and used chloroform as his non-polar solvent.  Wasn't a problem for the acidification, but when basifying, chloroform is no good.  He titrated his water solution with the intent of causing the TMA to oil out, but instead he got a bizarre brown precipitate.

(SWID also got this precipitate from basifying the first non-polar wash, an exceptionally stupid thing to do.  He still has them, although no idea with what to do with them.)

So, he filtered the precipitate, extracted the water with hexane (giving a light yellow color to the hexane), dried it over CaCl2 for 5 hours, and gassed with dry HCl.  At which time the liquid very rapidly turned a dark more-blue-than-green color.

SWID threw this in the freezer and got a beer to catch his tears in.

SWID isn't sure what went wrong, there are too many variables.  He DOES know, apparently, that the psuedonitrosite is good to go...color, reactions (particularly regarding acid-base) are all positive.

After that he is unsure.  Any expieranced bees opinion would be greatly appreciated.

SWID is tempted to use the Urushibara Al-Ni(A) catalyst write-up on rhodiums page, but several things seem off.  For one Asarone is supposed to be acid sensitive, but aliquats of acid are added at regular intervals.  This would be fine if the acid were being used up, but SWID was under the impression that the reaction proceeds thusly between aluminum and HCl:

2Al + 6HCl -> 3H2 + 2AlCl3
AlCl3 + 3H20 -> 3HCl + Al(OH)3

So that the HCl is actually acting as a catalyst in the reaction.

Would any expierenced bees have good suggestions regarding the use of Zn-Ni Urushibara catalyts?  Does one suppose that a similiar proceedure, in which Zinc and aliquats of HCl were added would be successful?  What about copious amounts of ZnCl2?  Also, a lot of zinc would be needed to make anywhere near the amount of H2(g) that a mole of aluminum produces.  (26.98g Al => 3 mol (67.2L H2) or 98.09g Zn to produce same).

Lastly, although SWID has never tried it, what about using the old Al-Hg amalgum?  Will it reduce both the the double bond and the nitro group?

Post-lastly, why in the hell did it turn BLUE when he gassed with HCl?  Of all the wierd shit...

SWID was smart enough to not use all his nitropropene however, and still has enough for another 10g run.  So, the question REALLY is, what is the most recommended method by those who have actually gotten success from said method.

Thanks so much.


hest

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Lowtec
« Reply #1 on: February 11, 2004, 10:34:00 AM »
I have littel geto eksp. but I would reduce the nitropropene to the ketone and then turn the propen int the amine by red.ammination. (ala the leucard rex. from p2p to amph.)
I don't understand your chlorofor problems. but one or two A/B's usual makes wonder.

Daphuk_up

  • Guest
Ok, so... The solution that SWID gassed has...
« Reply #2 on: February 12, 2004, 12:05:00 AM »
Ok, so...

The solution that SWID gassed has settled, with some dark seemingly polymerized gunk on the bottom of the flask, and the remaining liquid a light green color.

SWID considered that maybe the double bonds hadnt been reduced but the nitro group had been, thus resulting rapid reaction and polymerization in the presence of HCl.

A particular annoyance is that the first time he ran an U-Al-A reduction, he managed to isolate an extremely small yield of freebase (or so he thought), and upon gassing in Toulol the solution turned green then too.  SWID chalked this up to the fact that the PVC braided hose he had used to boil off excess Toulene had melted a bit and probably ended up in the solvent.  Perhaps that was not necessarily the case...

SWID still wants the U-Catalyst method to work, and has not quite given up hope yet.  However, he will likely follow the write-up using U-Al-A on rhodiums page, and see what it produces this time.

If it becomes clear that this method is not working, then the propanone route will be followed, but rather than using a leuckart, and amalgum will almost certainly be employed with ammonia gas solvated in methanol.  SWID doesn't prefer this route immeadiatly, simply because he has never done either reaction before.

The Leuckart probably wont be pursued due to several conflicting reports regarding yield, and also to the fact that SWID isn't in the mood to synth both Formic and Formamide (although he has done the exceptionally easy Formic Acid synth before).

As usual any suggestion, even a passing one, is appreciated.


hest

  • Guest
A/B
« Reply #3 on: February 12, 2004, 04:18:00 PM »
The point off the acid base extraction is to get rig of all the nasty stuff, only amines will 'survive'. Do this two times and see wath you end up with. Iff you get's nothing it's time to a new aproach.

Daphuk_up

  • Guest
Ok, SWID is going to try this: U-Zn-B(s), 5g...
« Reply #4 on: February 16, 2004, 03:19:00 AM »
Ok, SWID is going to try this:

U-Zn-B(s), 5g of TMPNP, and aluminum + HCl for IN solution hydrogen generation.  Worth a shot...

Also, in one of the U-Catalyst docs, there is a comment that nickel is ferromagnetic.  A quick check with Merck confirms this.  However, upon checking the catalyst itself as well as a US nickel with a powerful neodymium magnet, there appears to be no attraction whatsoever.  Indeed, SWID has used magnetic stirbars/stirring in U-catalyst reactions before without a hitch.

Last, could someone find this ref?  It seems like it might be interesting.

New type of Urshibara Nickel catalyst (U-Nic-N).  Activation of the precipitated nickel (precursor of Urushibara nickel catalysts) by refluxing with alcohols.     Kajitani, Masatsugu; Okada, Junko; Ueda, Tetsuya; Sugimori, Akira; Urushibara, Yoshiyuki.    Fac. Sci. Technol.,  Sophia Univ.,  Tokyo,  Japan.    Chemistry Letters  (1973),   (8),  777-80.  CODEN: CMLTAG  ISSN: 0366-7022.  Journal  written in English.    CAN 79:108478    AN 1973:508478    CAPLUS 

Abstract

A new method is described for activating pptd. Ni by refluxing with alcs.  The pptd. Ni activated in this manner exhibits a catalytic activity corresponding to acid-activated pptd. Ni.  The catalyst is useful for the selective hydrogenation of 1-octene (low isomerization) and cycloolefins. 

It's in English fortunately, so a translation won't be needed.