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  Ethylenediammonium diacetate - a mild and effective Henry reaction catalyst
 				by <rhodium@privacyx.com>
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This procedure, to use ethylenediammonium diacetate as a Henry reaction catalyst
was originally suggested by Osmium, and the following success rates was gathered
from various researchers who wishes to remain anonymous. 

Preparation of the catalyst:

A 150 ml beaker, containing 100 ml dry ether and 12.0 g (0.2 mol) of ethylene-
diamine, is placed in an ice-bath and a solution of 24.0 g (0.4 mol) glacial 
acetic acid in 20 ml ether is added with stirring at such a rate as to prevent 
boiling of the ether. The solution is left to crystallize overnight, then
filtered with suction, the crystals washed with ether and recrystallized from 
approximately 50 ml MeOH. Yield after drying in a vacuum desiccator is around 
27.5g (75%) of colorless needles, mp 114°C.

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Preparation of substituted nitrostyrenes, general procedure:

50 mmol of the substituted benzaldehyde, 60 mmol of nitroalkane and 5 mmol of 
ethylenediammonium diacetate is dissolved in 25-50 ml of iPrOH with stirring 
(with gentle heating if required to dissolve all solids) and the solution is 
left to stir at room temp for ~24 hours, whereafter the formed nitrostyrene is 
allowed to crystallize in the freezer for ~12 hours. The precipitate is then 
filtered off, washed with a small amount of iPrOH, sucked as dry as possible 
at the pump and air dried. The yields are typically 60-70%, with the exception
of the fluorinated substrates, as well as for piperonal, the latter due to the
formation of a large amount of a byproduct of unknown composition.

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Product                                           Yield
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Phenyl-2-nitropropene                           - 60%
4-Fluorophenyl-2-nitropropene                   -  5%	
4-(Trifluoromethyl)-phenyl-2-nitropropene       -  3% (4)
4-Methoxyphenyl-2-nitropropene                  - 71% 
4-Methylthiophenyl-2-nitropropene               - 57% (1)
2,5-Dimethoxyphenyl-2-nitropropene              - 50%
2,5-Dimethoxy-4-Methyl-phenyl-2-nitropropene    - 61%
3,4-Methylenedioxyphenyl-2-nitropropene         - 14% (1,2)
2,4,6-Trimethoxyphenyl-2-nitropropene           - 67%
2,4,5-Trimethoxyphenyl-2-nitropropene           - 58%
1-(3-Indolyl)-2-nitropropene                    - 37% (3)
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Notes:

(1) This nitrostyrene is unstable, and should thus be stored in the fridge.
(2) A large amount of a voluminous white precipitate of unknown composition 
    was also formed in the solution. A batch which used 10 grams of piperonal
    gave approx 4.5 g of this material. Further investigation is warranted. 
(3) The aldehyde is pretty insoluble in iPrOH, perhaps the use of a co-solvent
    (THF?) or much more of iPrOH would increase the yield somewhat.
(4) Allowing the mixture to stand in the freezer for two weeks gave 3% yield, 
    standard reaction times have given a maximum yield of 1.5%.

The procedure has been optimized for the preparation of 2,5-Dimethoxynitrostyrene, 
and the yield is typically very high for this product, usually exceeding 95%. 

2,5-Dimethoxynitrostyrene
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2,5-Dimethoxybenzaldehyde (83.1g, 0.5 mol) and ethylenediammonium diacetate 
(9.0g, 0.05 mol) was dissolved with stirring in 400ml isopropanol with gentle 
heating until a clear solution was obtained. Nitromethane (36.6g, 0.6 mol) 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 (0.48 mol, 96%). 

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