The example below uses a disubstituted benzaldehyde to yield a nitroalkene. This will work with other benzaldehydes as well but the color may vary at different stages. However, for the most part the rxn runs identical. It can be scaled up or scaled down with few problems, just remember when you quench with IPA if scaling up/down to use a lot more than you think you'll need. at least by ~200ml.
10g 2,5-DMB is pulverized into a powder and added to a 500ml flat-bottom flask, followed by 25ml nitromethane and 1.6g ammonium acetate as a catalyst. Try to make the acetate salt anhydrous as possible. It is very hygroscopic! I used a dessicator for 12-24h. You'll know the crystals are dry when no more puddles are visible. This makes the AmAc easier to weigh. Also having anhydrous conditions is a good thing as well because it won't promote as many H20-related side-reactions but I doubt it affects yields much. My yields always kicked ass.
This is then brought to a gentle reflux while magnetically stirred for ~45-60min. The color should progress from a light yellow to an orange, red, and finally a deep red(somewhat black...almost like black cherry kool-aid!). Heat is then removed and allowed to cool down a bit for about 15-30min. until it is no longer boiling but still hot. Watch out for the IPA/nitroalkene vapors! They will make you cry and cough(guess how I learned?)! The still hot mixture is quenched with ~200ml freezing cold 70% IPA to induce crystallization. Immediately the solution will burst into orange crystals(paste most likely).
This is poured into a buchner and vaccum filtered until no more liquid comes through the funnel. This is then washed with minimal amounts(just enough to cover the filter cake) of freezing cold IPA(70% or greater preferrably) to crystalize even more styrene and wash out any remaining polar junk. The nitroalkene is very soluable in IPA when hot and hardly when cold, making the IPA a great solvent for washing/purifying/re-xstalizing.
The nitroalkene is done washing once the color of the washes are no longer red and remain a light yellow/orange. If you're really anal a clear color is *probably* possible but you'll lose product purifying it(not worth it).(you can get buy with a deep orange color, just not red). Anything not red is absolutely fine. Dry the resulting pumpkin-orange crystals until crisp and anhydrous(ie. air dry, dessicate, buchner, vaccum, ect.). The MSDS says it's a lachrymator but unless it actually gets into your eye or it's piping hot while solvated in IPA you probably won't notice it. I didn't, with the exception of when I dissassembled everything and IT WAS HARSH!
It has light-moderate odor when dry, something similer to IPA with something spicey to it. Perhaps it's possible to purify it even more to remove the odor, however this is not necessary.
Yield ~90%
The resulting nitroalkene will burn like hell if you get it in your eyes(guess how I learned?) and besides that is fairly safe to handle to the touch but wear gloves anyways because it will eventually irritate your skin.
I'll probably be posting a followup sometime soon about performing a reduction via Hg/Al amalgam to yield the corresponding amine. Then I'll probably do a followup on how to brominate a disubstituted aromatic amine.
-PStain
10g 2,5-DMB is pulverized into a powder and added to a 500ml flat-bottom flask, followed by 25ml nitromethane and 1.6g ammonium acetate as a catalyst. Try to make the acetate salt anhydrous as possible. It is very hygroscopic! I used a dessicator for 12-24h. You'll know the crystals are dry when no more puddles are visible. This makes the AmAc easier to weigh. Also having anhydrous conditions is a good thing as well because it won't promote as many H20-related side-reactions but I doubt it affects yields much. My yields always kicked ass.
This is then brought to a gentle reflux while magnetically stirred for ~45-60min. The color should progress from a light yellow to an orange, red, and finally a deep red(somewhat black...almost like black cherry kool-aid!). Heat is then removed and allowed to cool down a bit for about 15-30min. until it is no longer boiling but still hot. Watch out for the IPA/nitroalkene vapors! They will make you cry and cough(guess how I learned?)! The still hot mixture is quenched with ~200ml freezing cold 70% IPA to induce crystallization. Immediately the solution will burst into orange crystals(paste most likely).
This is poured into a buchner and vaccum filtered until no more liquid comes through the funnel. This is then washed with minimal amounts(just enough to cover the filter cake) of freezing cold IPA(70% or greater preferrably) to crystalize even more styrene and wash out any remaining polar junk. The nitroalkene is very soluable in IPA when hot and hardly when cold, making the IPA a great solvent for washing/purifying/re-xstalizing.
The nitroalkene is done washing once the color of the washes are no longer red and remain a light yellow/orange. If you're really anal a clear color is *probably* possible but you'll lose product purifying it(not worth it).(you can get buy with a deep orange color, just not red). Anything not red is absolutely fine. Dry the resulting pumpkin-orange crystals until crisp and anhydrous(ie. air dry, dessicate, buchner, vaccum, ect.). The MSDS says it's a lachrymator but unless it actually gets into your eye or it's piping hot while solvated in IPA you probably won't notice it. I didn't, with the exception of when I dissassembled everything and IT WAS HARSH!
It has light-moderate odor when dry, something similer to IPA with something spicey to it. Perhaps it's possible to purify it even more to remove the odor, however this is not necessary.
Yield ~90%
The resulting nitroalkene will burn like hell if you get it in your eyes(guess how I learned?) and besides that is fairly safe to handle to the touch but wear gloves anyways because it will eventually irritate your skin.
I'll probably be posting a followup sometime soon about performing a reduction via Hg/Al amalgam to yield the corresponding amine. Then I'll probably do a followup on how to brominate a disubstituted aromatic amine.
-PStain
