Author Topic: High-yielding nitrostyrene catalyst  (Read 45719 times)

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  • Guest
« Reply #40 on: July 09, 2003, 07:59:00 AM »
Could the amorph substance be an imine?

I have used MeNH as a 5-20% aqueous solution in several cases of which some have and some have not been confirmed by analytical testing. Those which have been confirmed are:


I have tried other substances as well, but I took their identify "for granted". I'll see if I can find some space in my schedule to elucidate the amorphous solid's identity, if it appears not to be 3,4,5-trimethoxyphenyl-2-nitroethene.


  • Guest
« Reply #41 on: July 09, 2003, 09:30:00 AM »
I just found the chromatogram and MS of a recent experiment, viz anisaldehyde + nitroethane with 10% aqueous MeNH2 catalyst. The obtained 4-methoxyphenyl-2-nitropropene has not been analyzed, but has been subjected to Ba's toluene/PTC/NaBH4 reduction procedure. The resulting pale yellow oil has been analyzed and gave the following MS:

Since the M+ is 195 (which is the MW of 4-methoxyphenyl-2-nitropropene +2), I accept this to be 4-methoxyphenyl-2-nitropropane. This also means that the MeNH2 catalyzed reaction did work for this specific compound.


  • Guest
« Reply #42 on: July 09, 2003, 02:31:00 PM »
I'm not saying the methylamine procedure doesn't work. Just that it doesn't work in this specific case. Anyway I can repeat it, but I'm sure it is not the imine, the imine will be soluble, an in any case it will be less than a 20 % of the initial product (methylamine content), while I got a lot more of that thing. Furthermore we know that this particular aldehyde doesn't work well with EDDA and nitromethane, while 2,5 DMB works fantastically.
I think that doubts should be solve with a corporative work, so someone should try to repeat the procedure with a samll amount, fridge filter and try to solve the product in acetone.
I made the respective nitropropene with cyclohexylamine too (with no solvent) time ago, and I still have the product, that was good. May be that like with the NaBH4 reductions, the nitropropenes are easier to work with.


  • Guest
nitroethane problem
« Reply #43 on: April 20, 2004, 05:31:00 PM »
Hi bees!

Deemtermined: I once thought GAA just served as a solvent in Henry condensations, but I heard from my buddy SWIA that he recently tried using ammonium acetate catalyst with GAA/iPrOH solvent system, and got VERY ugly, red tar-like nitrostyrene (went down the toilet..). And then the question: why is the acetate made when ethylene diamine is used as catalyst (ED+2GAA=EDDA)? Perhaps the thought behind it is to avoid evaporating the catalyst (methylamine is even more volatile than ethylenediamine). Adding GAA to nitrostyrene crystals makes no sense to me. But as you got nice nitrostyrene w/o GAA, may I suggest you simply don't add any...  ;D  :P
(seriously, I suggest using EDDA)

Perhaps the following is a bit off-topic (I apologize) but the FSE is down at the moment, so I can't find the appropriate thread an have to ask here: SWIA has an OTC source for nitroethane, but the product in question contains ~40-60% NE, the rest being ethyl formate, ethyl acetate and butylalcohol. Although fractionally distilling several times, he hasn't managed to get high purity (at least all knoevenagel rxns gave him constantly 50-60% of the expected yield, with aldehydes, solvents and catalysts being lab-grade, and SWIA thinks the reason is his nitroethane) Since I wanted to help the poor guy, I suggested to make the nitronate salt by adding NE to aequ. KOH, then heating to remove EtOAc etc. (perhaps wash with nonpolar) and finally acidify and salt out the NE again.
Do you think my advice was right?  :P  Or is there a simpler method for removing said impurities?

THX for your help!



  • Guest
Solubility reasons
« Reply #44 on: April 20, 2004, 05:42:00 PM »
And then the question: why is the acetate made when ethylene diamine is used as catalyst (ED+2GAA=EDDA)?

Solubility reasons. Other salts like the hydrochloride and the nitrate are a lot less soluble in IPA.


  • Guest
re: solubility reasons
« Reply #45 on: April 20, 2004, 05:54:00 PM »

Rhodium: Perhaps I should have said "Why is a salt made at all?"  ;D

I would like to know what is the reason behind the fact that isopropylamine, butylamine and methylamine are used as free bases, whereas ethylenediamine is not?

(BTW ethylenediamine diacetate is also used without any solvent, luckily someone at the hyperlab decided to post in english  :)  

Post 412716 (missing)

(Hellowin: "Condensation of benzaldehyde and nitroethane", Russian HyperLab)
I wonder why acetate is used here.. is the free amine not soluble in aldehyde/nitroalkane??)

Greetz A  :)


  • Guest
Nef reaction
« Reply #46 on: April 20, 2004, 05:55:00 PM »
If you acidify a nitronate salt with an excess of mineral acid, the Nef reaction occurs, making a carbonyl compound.

To regenerate the original nitro compound it is necessary to acidify very slowly by dripping weak acid (e.g. 50% acetic) into the nitronate solution whilst stirring vigorously.


  • Guest
I get it, now.
« Reply #47 on: April 21, 2004, 07:03:00 AM »
Oh.  Oh crap, thats where SWID's nitroethane went.  Nef reaction, huh? :-[  :(  ::)   A good fifty mL of nitroethane wasted. >:(  

Hmm, does that mean that ethylnitronate forms acetaldehyde on decompisition with strong HCl?


  • Guest
« Reply #48 on: April 21, 2004, 11:47:00 AM »
does that mean that ethylnitronate forms acetaldehyde on decompisition with strong HCl

Yes. The yeild and purity of the acetaldehyde will probably depend on the temperature. Best results for the Nef are often achieved with quite concentrated acids and freezing temperatures. Some substances form a lot of blue/green by-products if the temperature is too high.


  • Guest
EDDA preparation
« Reply #49 on: May 15, 2004, 03:59:00 AM »
Hi bees!

Recently, I wondered why the acetate of ethylenediamine is made in nonpolar solvent...

As EDDA should be recrystallized from alcohol (MeOH, iPrOH) anyway, my idea was to mix GAA with alcohol, cool to below 0°C, slowly add (precooled) alcoholic solution of 0.5x molar amount ethylenediamine, chill to below 0°C, suction filter the formed crystals, and perhaps concentrate mother liquor with vac and cool again to get 2nd precipitation.

My experience is that it works fine as long as addition of the diamine solution is done slowly, with cooling to avoid evaporating the diamine, the so obtained EDDA is very pure and ready to use (after being dried) - and again one step less to perform! 8)

(and it avoids using nonpolar solvents)

But still I wonder why this alkylamine needs to be converted to its salt when being used as knoevenagel catalyst? BuNH2, iPrNH2, MeNH2 - all are used pure or in solution, but not as salts!! Does any bee know the reason?

Greetz A


  • Guest
lower yields with the freebase?
« Reply #50 on: May 15, 2004, 04:03:00 AM »
I believe it is the ethylenediamine which isn't stable, it turns dark and yucky upon storage.

Are you getting much lower yields with the freebase?


  • Guest
« Reply #51 on: May 15, 2004, 01:40:00 PM »
Hi vertus. This has been an ongoing discusion here at the hive. It's my impesion that the ammine is not so important, there are no 'golden' way to make the nitrostyrenes. Som aldehyde are har to work with, like 3,4,5-tmba and p-flurbenzaldehyde, and others work like a charm, lik 2,5-DMB.
My personal favorite is nitroethae/aldehyde 1:1 and methylamine in methanol(just enough to make a solution) at 25-50°C for some houers.
Barium ahve som exelent's post's abouth the subject.


  • Guest
not tried yet
« Reply #52 on: May 17, 2004, 07:56:00 AM »

Rhodium, I never tried ethylenediamine freebase as catalyst in condensations, but I don't think it'll give lower yields than if EDDA is used. Contrary, maybe yields could be raised in some cases: Barium references to Zh. Prikl. Khim., 31, 663 (1958) (a paper which I don't have acess to  :( ). But with interesting yields:

- Benzaldehyde/Nitroethane/Ethylenediamine, 50°C; 76% yield

- p-MeO-BA/NE/ED, 80°C; 100% yield(QUANTITATIVE!?)

- m-MeO-p-OH-BA/NE/ED, 20°C; 95%

And yields with simple benzaldehyde and paramethoxybenzaldehyde are both lower if EDDA is used!

Experiments to be done...

Greetz A


  • Guest
« Reply #53 on: May 21, 2004, 03:53:00 AM »
Thanks a lot for translating it!

I could kiss you for that!

(and I thought that putting the nitrostyrene solution under high vac over silica gel to get higher yield was MY idea!  :) )

And they REALLY distill their b-methyl-nitrostyrene!?! Twice?!

BTW (now that I read it again) I think the thermostat temperature for P2NP would bee somewhere between 60-80°C, like they mention it for 4MeOP2NP (example VII), but it's just a guess...

And to check if the diamine or its benzoate is the catalyst - well, distill your aldehyde (maybe over some carbonate salt) prior to use, use clear, non-coloured diamine (it sucks CO2 from the air and forms carbonates, becoming yellowish) and you'll see if the benzoic/carboxylic salt or the freebase is the "real" catalyst... ;)



  • Guest
Ethylenediammonium diacetate (EDDA) (lit. prep.)
« Reply #54 on: October 02, 2004, 08:08:00 AM »
Ethylenediammonium diacetate (EDDA) is prepared as follows:

A 250-mL, round-bottomed flask with a stirring bar and a pressure-equalizing addition funnel with a calcium-sulfate-filled drying tube is charged with dry ethylenediamine (12.0 g. 0.20 mol) and dry ether (100 mL). Acetic acid (24.0 g, 0.40 mol) in dry ether (20 mL) is added through the dropping funnel to the stirred solution. The reaction mixture is left at 4°C for 14 hr and the crystals are collected by filtration and washed with ether. Recrystallization from methanol provides 19.8 g (83%) of pure EDDA, mp 114°C, as white needles;

IR (KBr) cm?1: 3500–2000 (NH), 2180 (MH3+), 1650 (C=O), 1600–1400 (CO2-);
1H NMR (CDCl3) ?: 1.90 (s, 6 H, CH3), 3.20 (s, 4 H, CH2), 5.75 (s, 6 H, NH3+).

L. F. Tietze, G. v. Kiedrowski, K.-G. Fahlbusch, and E. Voss,

Organic Syntheses, CV 8, 353

Which in turn references the procedure to:
Tietze, L. F.; Eicher, T.; "Reaktionen und Synthesen im Org. Chem. Praktikum"; Thieme: Stuttgart, New York, 1981, p. 387;
Tietze, L. F.; Eicher, T.; "Reactions and Syntheses in the Organic Chemistry Laboratory"; University Science Books: Mill Valley, CA, 1989, p. 403.

Can anyone find any of the latter publications to see if there's any related information of value?


  • Guest
« Reply #55 on: October 02, 2004, 03:00:00 PM »
Do you think it is necessary to synthesize EDDA in advance? Maybe it is sufficient to use ethylenediamine as catalyst and using acetic acid as co-solvent.

From azole's post in this thread: 4-Methoxy-?-nitrostyrene (I). A solution of  anisaldehyde (5 g, 0.0368 mol), nitromethane (2.9 g, 0.0368 mol), ethanol (5 ml), and ethylenediamine (2 drops) was allowed to stand in a closed vessel in the dark at 8-10 °C. After 10 days the nitroolefin I was filtered off and washed with small portions of alcohol. Yield 6.4 g (97.3%), m. p. 86 °C.

So maybe you could add 2 drops of ethylenediamine to a solvent mixture of ethanol and GAA, or add the corresponding quantity of GAA to ethanol?