(Hive Addict)
08-05-04 20:28
No 523841
(Rated as: excellent)
Heterogeneous catalysts in the preparation of 2-aryl-1,3-dinitropropanes from beta-nitrostyrenes or benzaldehydes
Angélica Fierro, Marcos Caroli Rezende, Silvia Sepúlveda-Boza, Miguel Reyes-Parada and Bruce K. Cassels
J. Chem. Research (S), 2001, 294–296
Abstract
The use of heterogeneous basic catalysts (KF, NaHCO3) in the preparation of 2-Aryl-1,3-dinitropropanes from beta-nitrostyrenes or benzaldehydes is described, with one example followed kinetically by HPLC analysis of aliquots of the reaction.
.pdf made available by Kinetic in record time - thanks 
General preparation of 1-aryl-2-nitroethenes:
A solution of the corresponding benzaldehyde (10 mmol), nitromethane (20 mmol) and n-butylamine (1 mL) in glacial acetic acid (10 mL) was refluxed for 1 hour. The 1-aryl-2-nitroethene which separated upon cooling, was filtered and recrystallized in methanol. In this way the following nitroethenes were prepared:
1-(3,4-methylenedioxyphenyl)-2-nitroethene 87%
1-(3,4,5-trimethoxyphenyl)-2-nitroethene84%
1-(2,5-dimethoxyphenyl)-2-nitroethene 88%
...some other nitrostyrenes are reported in the original article.
--psyloxy--
(Hive Bee)
08-06-04 02:59
No 523902
Look, look - another Knoevenagel/Henry reference...
Well I don't know about 3,4,5-trimethoxy-BA, but with 2,5-diMeO-BA and nitromethane, results are even better with EDDA than with n-BuAm...
2,5-Dimethoxybenzaldehyde (83.1g, 500 mmol) and ethylenediammonium diacetate (9.0g, 50 mmol) was dissolved with stirring in 400ml isopropanol with gentle heating until a clear solution was obtained. Nitromethane (36.6g, 600 mmol) was then added, and during the next hour the solution turned a deep orange, and stirring was discontinued. The solution was then allowed to stand at room temp for 36h, and the orange crystalline mass was broken up with a large spatula and was filtered with suction until no more liquid came through. The crystals was then washed with 100ml cold isopropanol in the buchner funnel, and sucked as dry as possible. After air drying overnight, the crispy and intensely orange 2,5-dimethoxynitrostyrene weighed 100.5g (480 mmol, 96%).
BTW what would you want to do with 3,4-methylenedioxy-phenyl-2-nitroethene? Something like 3,4-MD-phenetylamine - is this active at all?
With EDDA, it seems impossible to make anything from 3,4-methylenedioxy stuff - so it's nice to have a reference for using n-BuAm...
(and the yields for 3,4,5 look pretty good BTW - dunno if this could be done with EDDA..)
...Now the question: would it be of advantage to prepare n-butylammonium acetate prior to using it in said condensation (or maybe it isn't possible at all)? Or is the acidic environment needed (why then)?
Greetz A
Pleased to meet you hope you get my name.
But whats puzzlin you is the nature of my game!
(Hive Addict)
08-06-04 06:56
No 523950
Hi armageddon, surely looks nice, haven't seen this one before. Where is it from ?
The MD compound was just included 'cause everybody likes MD around here, I *suppose* the reaction won't work much different with nitroethane. MDO-PEA is inactive. The advantage surely is that you get your nitrostyrene in ~2h worth of work.
--psyloxy--
(Hive Bee)
08-06-04 09:49
No 523973
It's from Rhodium's... (there should be a markup button for these words, too!)
"Ethylenediammonium diacetate - a novel nitrostyrene synthesis catalyst"
../rhodium /edda.ht
Also very interesting due to exceptionally high yields with certain substrates: The use of plain ethylenediamine w/o any GAA...
Post 508451 (azole: "ethylenediamine as a catalyst", Methods Discourse)
...but 2h rxn time seems pretty unbeatable! Except with methanolic, anhydrous methylamine maybe...
And I really wonder if there would be any advantage in making the acetic salt of butylamine and use that as catalyst - just like is done with ethylenediamine...
Greetz A
Pleased to meet you hope you get my name.
But whats puzzlin you is the nature of my game!
(Newbee)
08-06-04 21:54
No 524031
Would all agree that this looks like the most promising method as far as ease (“fool proofness”) and yield for 3,4,5? Was thinking bout cyclohexamine but this has changed my mind.
Very limited starting material (and TLC experience) so yield is of great concern.
Thanks!
(Hive Adickt)
08-07-04 15:55
No 524056
I dont think the matter is that simple. The henrykondensation is a trickey one. Personal I think that the barium way is the best one (Nitro:aldehyde:MeAm 1:1:cat in just enough alkohol).
Especial the 345 condensation with nitromethane is trickey so make a test or two before you throw all your lovlie tmba into the reacton.
(Hive Bee)
08-25-04 21:04
No 527303
Methylamine is indeed better in terms of avoiding polymerization, which can be a serious problem with TMBA. But availability is bad for some bees - and butylamine is the "standard alkylamine catalyst" in jornal articles, you should be able to find information about its use together with TMBA if you search thoroughly. (Maybe ask PolytheneSam?
)Greetz A
Pleased to meet you hope you get my name.
But whats puzzlin you is the nature of my game!