phenyl-2-nitropropene recrystallization issues

joe_aldehyde · huxleys associate

as nobody seems to pay any attention to my ultrasound thread, i'll have to ask this here: my product out of that reaction is an egg-yellow oil (probably diluted with some nitroethane and benzaldehyde) which i can't get to crystallize. i put another batch in the rotavap and aspirator vacuum attached, but additional to the solvent getting sucked off, my product apparently polymerized and has now a dark red colour (i guess i can throw this away, can i?)

i previously washed all my current batches with water and separated the oil layer, then stored it in the freezer. i kept scratching the beaker walls, but crystallization wouldn't set in.

what do i do to achieve crystallization? i have about every solvent at my disposal, but i'm rather unsure which one to use (i actually had some trouble getting p2np out of my beakers using acetone...strange enough).

brain · Linguist Extraordinaire

my friend was wery nerwous, when he afer heathing it for 6-8 hours get red oil whih dont want to crystalize eawen when freezed owernight in -10 C !! he accedenly dropped some Fe powder in mixture, and he obserwed quick crystalization... the Fe powder was remoowed when P2NP was recrystalized wit magnet (electromagnes).

but in your case there mabey is to low yeld, and you will hawe to destill nitroethane+benzaldehyde? [steam?]

Bumblebee · Tue May 24, 2005 11:59 pm

Add to the liquid reaction mixture, equal amount of warm water, decant. then add cold water, decant also (not necessary to get all water out). this will remove some benzaldehyde too because it floats oily on top of the water.

Use distilled H₂ O...

finally add some more water to your liquid and set it aside in the freezer. If there are no crystals in 5 or 6 hours or so, you can:
- shake a bit,
- scratch the walls of the RBF or whatever with a glass rod
- add a seed crystal of nitropropene...
- set it back to freezer
- speak a prayer to the almighty god of chemistry... Wink

if it does not crystallize at all, you may have some solvents in your fluid, maybee any kind of alcohol... EtOAc... or did you use toluene?

some oily liquids are inhibiting the formation of P2NP-crystals, maybee your aldehyde was not clean enough..

got an red oily mixture too when i tried to do a Butylamine condensation to MD-benzaldehyde wich was dissolved in 40%Phenylpropylalcohol... mixture became red dark, and the nitroalkene did crystallize very hardly...
yield: never over 25% Crying or Very sad

will have to clean that fuckin´aldhyde

joe_aldehyde · huxleys associate

i already washed the shit out of my previous batches, no luck so far. the product must be somewhat contaminated and i'm pretty anxious about trying to strip possibly remaining solvent off on the rotavap as one batch turned red Sad

i didn't use any solvent, just plain benz + nitroeth in an ultrasound reaction (see the respective post for details). i followed the instructions from rhodiums page.
my aldehyde was food grade so i guess it must be quite pure.

how did you manage to get ahold of MD-benzaldehyde? did you synth it yourself? i have been investigating a while into demethylation and methylenation procedures but well...it's all a bit vague in terms of practicability (besides the pyridine*HCl microwave demethylation but i can't be tricked into using stuff that affects my bolloks).
you cold try to do a darzens condensation (to yield MDP2P) to your MD-benzaldehyde (which is also called piperonal if i get you right), look up any rhodium mirror and search for darzen.

IndoleAmine · Dreamreader Deluxe

if you ask me, the only successful condensation you did get is the one which turned red upon solvent removal.

Reason: p2np IS red when liquid.

Try adding some grains of clean sand, some naCl or even some Fe powder, and yes washing with mucho d.H2O removes everthing but the poduct very nicely.

Vigorous prolonged stirring of 40g red p2np oil with ca. 800ml d.H2O for 20 minutes once produced a huge solid lump of yellow massive nitropropene crystals when the chemist returned from a break, long ago....

(but scratching while ice-cold usually works very well too, preferably with something made from steel = harder than glass, cause it fucks up your beaker pretty nicely Wink

and thus generates a lot of tiny glass nucleation points....)

i_a

joe_aldehyde · huxleys associate

is p2np supposed to be heavier than water? the red stuff floats on top. but then again, if the red stuff is p2np, i got quite a nice stock to experiment with now Smile

IndoleAmine · Dreamreader Deluxe

Sorry, heavier than H2O.. Sad

(sounds like heavy nitroethane overload)

joe_aldehyde · huxleys associate

has anybody ever even attempted said ultrasound-catalyzed reaction?
how heat-sensitive is p2np? 100deg.c enough to make it polymerize?

plus i thought that nitroethane would be separated from the oil when stirring with water (nitroethane is miscible with water to a certain degree).

Bumblebee · Wed May 25, 2005 7:06 pm

The liqiud is heavier i think, because it is almost on the bottom....
the crystals settle mostly to the bottom too... but some is always floating around.

I don´t know the Ultrasound rxn... What did you use as US-source?
but there should be something crystallizing at all, just a very liitle something...

The reaction was done cold (at roomtemperature) too, and there were needles of P2nP forming straight away in the solution without cooling or anything (needles up to 3cm long an 2mm in diameter that where really light yellow to canary in color)

My MD-Benzaldehyde? No, sythezising it by myself was not successfull, until yet.
I just bought a something that is containig much of it (around 65%) and that is cheap.
I metioned it a time ago but nobody did care really about! I was asking for seperation of the to containing compounds...

I do not manage with the seperation very well. I never got crystalline Piperonal, since i didnt get rid of all the Phenylpropylalcohol (hydrocinnamic alcohol) in there. Crying or Very sad

But i am a optimist bee, i tried just the Butylamine condensation with the liquid i got, and Bingo: 25% of expected aldehyde got conversed to MD-P2nP. Mr. Green

and 25% means that you can get around 20g of it for ~10$ of material cost (incl Nitroethane etc.) and that´s good enough for me just for fun.
I don´t know what happens to that alcohol while the condensation, but there might be anyone out there who can say me?

@joealehyde: try do to a normal knoevenagel condensatin with your precursors you already have! reflux for 4 hours, wash w/H2O, cool, and there should appear some crystals.
if it fails there is something wrong with your precursors, i think.

but i would love to hear you scream *success*.
you can then go on and refine your ultrasound technique...

joe_aldehyde · huxleys associate

my ultrasound source was a professional lab US cleaner bath with adjustable frequency and amplitude. 250W powered.
sadly, i don't have any n-butylamine, but i've seen a few references to methylamine as a knoevenagel catalyst, too.
i've already tried out using methylamine in the ultrasound reaction but since i don't know what it should look like, i dropped a few grams of NH4OAc in as i thought that the mixture should have become much darker, which it did upon NH4OAc addition and subsequent irradiation for a few hours.

if anybody has some references (apart from what i found at the hive) concerning the condensation with methylamine as catalyst, please pm me or post it here. i'd be happy to do a few trials and writeups.

Sandmeyer · Thu May 26, 2005 3:45 am

IndoleAmine · Dreamreader Deluxe

Star-light · Blacklight bulb

joe_aldehyde · huxleys associate

yes i can do TLC, what solvent system do you suggest?
can i also drop methylamine aq.40% and GAA together with MeOH in the flask? i wonder if the water already present is likely to pose problems. or can i just neutralize aq. methylamine with GAA or plain 98% AA and then evaporate the water?

IndoleAmine · Dreamreader Deluxe

98% AA IS GAA...

And yes you can simply neutralize aequ. 40% MeAm soln. with excess GAA and use whatever lower alipathic alcohol you have....

(if you'd looked around a bit, you would've found a thread by Barium in the old Hive threads dealing with -guess what- using aequous methylamine...)

i_a