Author Topic: Phenyl-2-nitropropene crystallization  (Read 4946 times)

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armageddon

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RE: Starlight: not sure if its optimal...
« Reply #20 on: February 16, 2004, 12:47:00 PM »
I think you are absolutely right about that, starlight!
From SWIMs experience, 1.1 grams ammonium acetate works perfectly with 6ml (about 6.5 grams) benzaldehyde and an excess of 18 ml nitroethane. Refluxing this for 6 hours yields a dark cherry-red, viscous oil, distilling off the excess nitroethane and EXCESSIVE washing (up to 4 or 5 times!) with plain tap water will almost surely produce loads of crude orange crystals at some point of the procedure (even in the separatory funnel, while being drained! watch out..) The weight of this raw nitropropene amounts to 6.4 grams, recrystallisation would probably reduce the yield, but I don't know as SWIM usually keeps his raw P2NP in the freezer until needed for further investigations (they are reXtalized from boiling iPrOH as needed ;)

(yes, some of you will think that using that much nitroethane is a bad idea cuz its too precious to them, but hey, I found a source for it right around the corner in my home depot - sorry but I won't tell you! For you poor bees who don't share my knowledge, supposedly isopropyl alcohol as solvent will work as well (as long as its anhydrous)I asked SWIM 'bout that too, but he said that he never tried it... :P  ;)

L42L

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nitro TLC
« Reply #21 on: February 18, 2004, 10:43:00 AM »
After some thought (not to much) and Hest’s suggestion, TLC is looking more and more indispensable, as starting material (3,4,5-BA) is severely limited. Any bee have some thoughts concerning suitable solvents for a TLC (commercial, on plastic) of a 3,4,5-p2np synth (cyclohexane in GAA). She doesn’t really have the option of experimenting as this is a one time event. Iodine will be used for visualization.

Is there some magic table (library/WWW)of different chromatography (TLC, column, high pressure) solvents/rates for different compounds (or “like” compounds or functional groups…) that she’s oblivious too?

Sorry if this off topic.

thanks

hest

  • Guest
TLC
« Reply #22 on: February 18, 2004, 11:27:00 AM »
1: Get some UV-light/Blacklight.

2: Read the Paragraph "Chromatography" at Rhodium page (ner to the bottom.

3: When you have read it all ask some more, wee will still bee here

Grignard

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Try propylamine, much faster than n-butylamine
« Reply #23 on: February 19, 2004, 02:45:00 AM »
Try propylamine, much faster than n-butylamine and boil it with the benzaldehyde and the nitroethane without solvent.. when the reaction turns deep orange (1/2 h) this crystallise easily when the temperature is lovered, after the water is seperated out with a sep funnel!! the sep funnel induce crystalls from the drop drying in on the opening, just scrape this into your beaker.. this also work with ammoniumacetate and i have also did several mix with both propylamine and ammoniumacetate.. But dont put in solvent because this have to be removed before crystallisation..

armageddon

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Re: Propylamine catalyst
« Reply #24 on: February 24, 2004, 10:32:00 AM »
Grignard: could you please post some reaction details for the condensation of benzaldehyde w/nitroethane using Propylamine/NH4OAc as catalyst, especially ratio/amount of reactants, time/temperature (reflux?)? I would greatly appreciate it...

THX :)

(Doh, just overread, seems you already answered my 2nd question, 30 minutes at reflux... sorry!)

armageddon

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Nitropropene crystallisation
« Reply #25 on: February 24, 2004, 10:51:00 AM »
Oh, and since this is the "probs w/Xtalisation"-thread about nitropropenes:

If your post-reaction mixture doesn't behave like it should in terms of producing crystals, try to pour it over crushed ice, let that melt and filter to recover P2NP crystals...

I think it's the combined effects of sudden cooling, giving impurities a possibility to be "washed out" (perhaps they even "creep" into the ice? dunno..) and exposing the P2NP oil to a surface of solid crystal working as seeding crystals that makes Xtalisation happen here...

For SWIM this always works as a last effort before thinking he's fucked up and throwing away the whole shit; 'cuz workup is a bit hard due to the crystal size being very small, clogging filters, but it's always worth a try before discarding what you prepared in hours of lab work, breathing toxic fumes... :(  ::)  :)  ;D

Offline futurealchemist

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Re: Phenyl-2-nitropropene crystallization
« Reply #26 on: January 28, 2017, 04:30:55 AM »
nitro compound and aldehyde into IPA with ethylenediamine diacetate as a catalyst. allow to react at room temp for a few days and set into fridge to crystallize. voila.

Offline Tsathoggua

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Re: Phenyl-2-nitropropene crystallization
« Reply #27 on: January 28, 2017, 02:15:00 PM »
One could try TETA (triethylenetetramine) as amine catalyst, using GAA, and once the reaction is complete.

This was done with 2,5-dimethoxy-4-methylnitrostyrene, and when complete, the entirety of the reaction fluid was poured onto ice. The result, crystallized near instantly, after which, filtration at the Buchner, and then washing with H2O cleaned it up nicely. Did a final recrystallization from ice-cold MeOH, and that removed the very last traces of pumpkin-orange, which in any case formed only a slight halo around the exterior of the mass of crystals, which were filtered off from the ice/traces of ice water from its melting, in this case, whilst Tsath' has never done it with a nitropropene, formation of crystalline product was immediate.
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