Author Topic: 2,5-diMeO-phenylnitropropene - the "cold" way.  (Read 2051 times)

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  • Guest
2,5-diMeO-phenylnitropropene - the "cold" way.
« on: April 26, 2002, 09:02:00 PM »
This is what the ghost of Vitsh's uncle's grandmother's imaginary friend told me:

Based on

"In 35 ml MeOH there is dissolved 2,4 g 2,5-diMeO-BA (made from hydroquinone--->p-MeO-phenol--->R-T formylation ---> methylation w/MeI in MeOH/KOH, recryst from MeOH) and 1,4 g EtNO2 (made from NaEtSO4 and NaNO2) and all is placed into an ice/salt bath with overhead stirring. When the temp. falls down to 0 C, there is added solution of 1 g KOH in 5mls water so that the temp. never rose above 2 C. Yellow solids precipitate. The mixture is further stirred for 1 hr at -2...-4 C.
The mixtr is poured into 100 mls icewater, stirred on icebath until cooled to zero and filtered.

Yield 2,4 g of canary-yellow crystals (74%)"

Unfortunately, Vitsh's ancestor's imaginary friend didn't know about Zn being unsuited for reduciton of nirtopropenes, and when Antoncho told him about that, it was too late :( . The reduction failed, giving 0,9 g of yellow oil, none of which was amine. Well, it was his last aldehyde, but he can always methylate himself some more 8)


Edit: it was shortly noted that the reaction mixture was not acidified, as it should have been - which, of course, irreversibly compromises the performed procedure; specifically in terms of obtained yield. DO NOT use it as it is. The further clarification on the subject is yet to come.


  • Guest
Choose one please
« Reply #1 on: April 26, 2002, 09:29:00 PM »
The ghost of Vitsh's uncle's grandmother's imaginary friend:

A): Forgot to acidify the reaction mixture before filtering

B): Did acidify, but forgot to tell you he did

C): Intended to make the K-salt of 2,5 DiMeoP2NP

D): None of the above, but...............................

Hansje high in proteine and fibre!


  • Guest
Golden yellow sounds wonderful.
« Reply #2 on: April 26, 2002, 11:54:00 PM »
Golden yellow sounds wonderful. Seriously marvelous marvelous oh what glory. The best color for this is a amber but the final yield is a golden yellow with dark overtones if I remember correctly. Still the nitropropene aint really worth a whole lot when you think about it. SWIM squeezed the final bit out from a third recrystalisation and scrapped it coz it looked dark. Yeah but SWIM also remembers being excessive in te amount of solvent used for recrystallisation. Excellent reductions though. Say, are you sure this works? Sounds a bit fishy if you ask me. I mean you're method aint eactly cutting edge..


  • Guest
« Reply #3 on: April 27, 2002, 12:48:00 AM »
I believe that this rxn produces the nitroalcohol that is then dehydrated to the nitropene when adding HCl. If he didn't acidfy he could get that nitroalcohol and try to reduce it, but anyway it should give the aminoalcohol. May be the aminoalcohol remained in the strong NaOH solution, may be not... Is it possible ?


  • Guest
« Reply #4 on: April 27, 2002, 06:33:00 AM »
Damn it, actually i realized the mixture hasn't been acidified as it was supposed to right after i posted it - damn it, but it was too late :-[

I asked Vitsh about that and expect to get his answer shortly after he wakes up - he lives about 5 hours 'earlier' than me, geographically speaking.

So, if it turns that he indeed made a mistake, here are my thoughts:

1) It is possible that nitroalkene forms only after the hydrolysis stage; however - why then in the analogous preps of nitroalkohols the reaction time is always from 1 to 3 minutes, strictly measured by clock?? Obviously, it needs to bee stopped at that stage, no?

2) In any case, w/out acidification the product one arrives at is a sodium salt. NitropropEnes also form salts, don't they?

Decomposing that salt is probably the stage where most of the yield goes down, here's a quote from


"...Primary and secondary nitro paraffins (nitroalkenes - a typo here! -) are acidic in nature and form sodium salts. When mineral acid is added to these sodium salts, the nitro paraffins are regenerated. The action is different, however, when the sodium salts are added to an excess of the acid. In the latter case aldehydes or ketones are formed with the evolution of nitrous oxide."

So, to maximize the yield it might bee beneficial to add the acid very slowly, as well as to use a weaker one - like AcOH, which i also have seen in one of the nitroalcohol procedures.

Again, bees, i'm terribly sorry to post misinformation - i'll edit the above post, so it needs not to bee classified as 'misinforming'; but please, take off the 'excellent' rating from it.



  • Guest
« Reply #5 on: April 27, 2002, 09:01:00 AM »
That Nef-reaction on Rhodium's page has me puzzled. Other nitroalkene-to-carbonyl reductions call for pre-reduced Fe + HCl or Sn + HCl etc. Would just dumping the salt-form in excess acid work as well?

Hansje high in proteine and fibre!


  • Guest
styrene not propene
« Reply #6 on: April 27, 2002, 09:46:00 AM »
Oops sorry, wrong page - too much EtOH  :P


F.G.P. Remery, Soc. 99, 282 (1911)
S.Sugasawa, H. Shigehara, B.74, 459 (1941)

Soc = Journal of the Chemical Society, London
B = Berichte der Deutschen Chemischen Gesellschaft

Unfortunately, I can't find 2,5-X in my book.

2,3-diMeO-phenylnitropropene (79%):

N.Mitsurube, Y.Nakawa, M.Koremura, C.A. 60, 13184 (1964)
C.B.Gairaud, G.R.Lappin, J.Org.Chem. 18,1 (1953)


  • Guest
« Reply #7 on: April 27, 2002, 11:05:00 AM »
Dissolve 1x mol 2,5-diMeO-PhCHO in 1.05x mol EtNO2, add 0.06x mol cHxNH2 (or etc.), leave in a dark place at room temp. for 10 days. Dump the solid yellow mass into cold MeOH and stir, filter and dry. Yield: ~75% 2,5-dimethoxyphenyl-2-nitropropene as bright yellow xtals. Do NOT use boiling MeOH to rextallize.

- Azarius -


  • Guest
« Reply #8 on: April 27, 2002, 11:12:00 AM »
Hansje, the Nef reaction works only on nitropropanes, not nitropropenes - that's why i said there was a typo on Rh's page.

I have no idea what happens to nitropropenes under the same conditions, maybee Rhodium or some other knowledgeable bee can tell us.

As i said, i am not 100% positive where dehydration of nitroalcohol occurs - immediately after condensation or upon acidification, i still think the former. But it seems quite logical that nitropropenes also form salts w/alkali - they should bee even more acidic, no?

So i suggested the same measures to prevent them from turning into somth else than is desired , that can bee used for nitroalkanes. It is purely speculative, of course.



  • Guest
« Reply #9 on: April 27, 2002, 11:51:00 AM »
Excellent, Azarius!

Since you brought it up, may i suggest a somewhat simpler version of the same procedure (submitted to HyperLab by Yura):

J.O.S. Perkin II, 1974, 642

250 g piperonal is dissolved in 900cm3 95% EtOH and there is added 150 mls nitroethane, 10 g CH3NH2*HCl and 8 g sodium carbonate. After a brief stirring the mixture is left in a dark place for 2 weeks. It is then poured into 7 l water, the precipitate filtered, washed w/water and air-dried. Recrystallization from small qtties of EtOH.

Yield 87%



  • Guest
Intersting to see if this one actually works.
« Reply #10 on: April 27, 2002, 03:59:00 PM »
Intersting to see if this one actually works. but need to get some TLC plates first or maybe just try a mp. Now are you sure the product was pure i.e does it give a sharp mp?


  • Guest
« Reply #11 on: April 27, 2002, 04:46:00 PM »
Well i am happy to tell you guys that Vitsh just misdescribed his actions - he says it was ice 2N HCl acid, the color change was also consistent with the known procedure.

He always follows the procedures very strictly, that is for sure.

I can't edit the original post any more.



  • Guest
Zn failed
« Reply #12 on: April 27, 2002, 05:52:00 PM »
So it seems Zn failed really.
I prepared the 2,5 DMP2NP by dissolveing the aldehyde in 1.1 excess of nitroethane and adding 6 % molar cyclohexylamine. Yield was so so, 50+ % and a TLC showed two spots. In rhodium's page there's a entry:

In wich is showed that sometimes the preparation of nitrostyrenes in this way, but using alcohol as solvent gives other byproducts.


  • Guest
« Reply #13 on: March 09, 2003, 10:11:00 AM »
Could hexamine be used as the amine for one of these condensations.???


  • Guest
Something fishy with this method........
« Reply #14 on: March 09, 2003, 10:55:00 AM »
OK, guys! This method doesn't seem to work as promised.

1st of all, Vitsh's product was to a large extent the starting aldehyde - due to unclean EtNO2.

Then, two different Hyperlab bees tried this and both times got the result: a yellow oil that didn't xtallize no matter what. Probably, nitroalcohol.

Both times everything was done as described on Rh's page. For 2,5-diMeO-BA. Using the same reagents in 'classical' synth with AcOH/NH4AcO gave excellent outcome.

I wonder if the proc described by Vibrating_Lights will work better?[doubt]

Anyway, please reset the rating for the 1st post of this thread and leave a notification that there's smth fishy w/this method.



  • Guest
WHen the acid id added properly the product is
« Reply #15 on: March 10, 2003, 07:52:00 PM »
WHen the acid id added properly the product is markably different than when the acid is added slowly.


  • Guest
2C-H and several related intermediates
« Reply #16 on: May 13, 2004, 09:30:00 PM »
This article has been mentioned before in the following posts:

Post 302034

(Natrix: "styrene not propene", Chemistry Discourse)

Post 398546 (missing)

(hypo: "electrolysis", Novel Discourse)

Die Oxydation einiger ?-Phenyläthyl-pyridinium-Salze (II)
S. Sugasawa & H. Shigehara

Chem. Ber. 74, 459-469 (1941)


10g 2,5-dimethoxybenzaldehyde is dissolved in 50 mL absolute ethanol together with 3.8g nitromethane, 200mg anhydrous sodium carbonate and 200mg methylamine hydrochloride is added, and the mixture is allowed to stand for about 100 hours at room temperature, during which time 9.6g crude nitrostyrene formed, pure enough for use in the reduction. Upon recrystallization from alcohol, the nitrostyrene formed yellow-orange needles melting at 119-120.5°C.

9g of 2,5-dimethoxy-?-nitrostyrene was suspended in a mixture of 200 mL ethanol, 100 mL glacial acetic acid and 30 mL conc. hydrochloric acid, and reduced for 4 h at 30-35°C using a (treated?) lead cathode (0.07 A/cm2). The resulting colorless solution was worked up in the usual manner to yield 4g of 2,5-dimethoxy-?-phenethylamine, bp 148°C/8 mmHg. The HCl salt formed colorless needles, mp 139°C.

Also featured in the article: 2,5-dimethoxybenzaldehyde is turned into 2,5-dimethoxyphenylacetonitrile using the Rhodanine procedure, hydrolyzed with ethanolic sulfuric acid to ethyl 2,5-dimethoxyphenylacetate, reduced to 2,5-dimethoxyphenylethanol with sodium in ethanol and finally brominated with phosphorus tribromide. The same procedure is also performed on 6-Methyl-3,4-dimethoxybenzaldehyde. Physical data given for all intermediates.


  • Guest
Re: Yield: ~75% 2,5-dimethoxyphenyl-2-nitroprop...
« Reply #17 on: May 14, 2004, 05:54:00 AM »

Yield: ~75% 2,5-dimethoxyphenyl-2-nitropropene as bright yellow xtals. Do NOT use boiling MeOH to rextallize.

Just curious as to why this particular nitropropene shouldn't be recrystalized in this manner?



  • Guest
« Reply #18 on: May 14, 2004, 09:32:00 AM »
SWIp has tried the above mentioned "cold" method for this nitropropene... 25dmb/1.1x mol EtNO2 + 6mol% cHxNH2, etc. the yellow oil is v.tricky to xtallise, but it is possible... IPA seems to work as a good (re)xtallisation solvent, but you must (pref. vacuum) filter while the IPA is still as cold as possible, otherwise your product will be oily xtals that don't dry. SWIp found that better yields with less xtallisation troubles was got by preparing the "cold" rxn mixture as above, but then heating under reflux for 4hrs or so instead of just leaving @rt for a cpl weeks...