2,5-Dimethoxynitrostyrene in 96% yield

[Rhodium]

A well-known bee sent me the following success story about his application of EDDA as the catalyst for the condensation of 2,5-Dimethoxybenzaldehyde with nitromethane:

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%).

See

http://rhodium.lycaeum.org/chemistry/henryrxn.txt

for the preparation of the catalyst.

http://rhodium.lycaeum.org

[blue]

tres    Rhod! any thoughts on how myristicinaldhyde might stand up in this proceedure?

as in cobalt

[hest]

Sounds great, for mee it' goes in the 80's. But why is 2,5-dmba so reactive, vhen i try the same on 3,4,5-TMBA the yeald is app. 30%.
I can't see why the Neff on 3,4,5-TMBA is going so bad. Annyone with more luck ?

[Lilienthal]

Maybe the low yields of the fluoro compounds and of 3,4,5-MeO-nitrostyrene are caused by incomplete crystallization. What does TLC say about that?
Could the white byproduct be the intermediate R_x-Ph-CH(OH)-CH₂-NO₂?

[Rhodium]

Checking with the list of yields of other nitropropenes, myristicinaldehyde might work all right, if it doesn't run into the same problems as with piperonal.

The reports on the fluorinated substrates only report isolated yields, and nothing about TLC, so it is fully possible that the problem is due to incomplete crystallization.

My guess why the yield is so high with 2,5-dimethoxynitrostyrene is that it is only very sparingly soluble in isopropanol, so that any formed nitrostyrene is precipitated, and thus the equilibrium is shifted to the right much more than with other substrates.

http://rhodium.lycaeum.org

[lostboys]

try cyclohaxamine instead for a complete yeild with 345
and so easy, when you add water to the rxn bang lots of yellow orange needles .