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Phenyl-2-nitropropene crystallization

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Antoncho:
i've read of more than half a dozen tries of the 'cold method' on both straight BA and 2,5-diMeO-BA and NITROETHANE and neither of them has ended in a success.

With nitromethane it seems to work OK every time.

So i suggest we put a small question mark beeside that doc on Rh's site - obviously it needs to bee at the very least optimized.

Stralight - you report seems to bee quite interesting. Could you give us more details, please? (the yield, time, temp, solvt ratio etc.) Curiously, there hasn't been, i beelieve, a published/posted success w/straight BA and NH4AcO - at the very best yields achieved ~50%. IMHO/AFAIK.



Antoncho

Bandil:
SWIM has had some problems with BA's in the past. Especially nitropropene's made from 2,5-DMBA. It was even worse(of course) when the starting materials was less pure. SWIM is using the following method which has worked for ALL compounds tried so far, no matter how pure/impure the materials have been:

The benzaldehyde and nitro(m)ethane are reacted ala barium with methylamine as catalyst. When the reaction is over the product rarely crystallizes if the starting materials have been less pure. When the whole lot has cooled, the GAA is added and the whole thing is dissolved in small amounts of DCM. This is washed 2-3 times with water and then stripped of solvent. With some following cooling and maybe a little scratching followed by recrystallization if the crsytals aren't nice enough, this provides SWIM with yellow-beautifull crystalls every time!

Good luck.

Regards
Bandil

Rhodium:
Wash the whole post-reaction mixture with vigorous shaking with 1/3 its volume of water, followed by 1/3 its volume of conc. sodium chloride, and if it doesn't crystallize already in the sepfunnel, drain it into a beaker, scratch the inside of the beaker with a glass rod, and then recrystallize it from methanol or isopropanol.

If all else fails, make a seed crystal of phenyl-2-nitropropene using this method: https://www.thevespiary.org/rhodium/Rhodium/chemistry/edda.html

Then add such a crystal to your liquid phenyl-2-nitropropene - it will crystallize immediately. Always save a seed crystal for future use of all hard-to-crystallize compounds, you will never regret it!

starlight:
Antoncho:

Time ~6hrs
Temperature: reflux
Solvent: None, just equimolar BA and Nitroethane
Yield:

hest:
This is an ongoin storry.
Reflux in accetic acid for 2-3houer usual gives 70-80%
Reflux in nitroethane usual gives 75-80%
MW is a bit trickey, iff you stop before the polimerisation begins(lot's of TLC), then yeald is in 75-80%, else in the 50%
3,4,5-trimethoxybenzaldehyde and bnitromethane is notorius hard to work with (yeald 30-60%), rhodium have posted a synth with KF ect. haven't trye't yet.
2,5-dimethoxybensaldehyde works alwayes greath, yeald in th 80-90%
Mu personal eksp. with differen catalysators is that it dosen't matter much.

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