SweetHomeSunscreen - 8-8-2014 at 03:40
Greetings. Apologies if this type of thread isn't welcome here, but I did see similar discussions.
I attempted to make 2,5-dimethoxynitrostyrene by condensing 20g 2,5-dimethoxybenzaldehyde with 12g nitromethane and 2g cyclohexylamine. The aldehyde
was dissolved in the nitro then catalyst added, stoppered and left for 48h at RT. Way too much amine was used I think and should have used a solvent
but...
I expected an orange crystalline mass, I got a dark red ball of putty. From repeated ethanol crystallizations I got around 10g orange powder. This was
re-x a further 4 times and now the solvent is pretty clean but I still have no 'orange needles'. I do however, have very very small needle like
crystals, no more than 1mm long and around the width of a thick human hair. Aside from the shitty yield, have I got a clean product?
I was expecting large crystals, from other aldehydes I've always received 0.25-1inch long needles so I think this is still impure. Any other solvent
suggestions or procedures?
Or if anyone has a picture of the compound I'd be most grateful, google won't show me anything.
Thank you very much.
Is it possible I have just reclaimed unreacted aldehyde dyed orange?
[Edited on 8-8-2014 by SweetHomeSunscreen]
solo - 8-8-2014 at 05:44
....here is a sample of similar reaction with pictures.....solo
https://www.erowid.org/archive/rhodium/chemistry/345-meo-ns....
Scr0t - 8-8-2014 at 16:02
I have observed that with this reaction the time given by Shulgin is too long (4hrs).
I have run this with an ammonium acetate catalyst (home made) with the same proportions as described by Shulgin but was concerned with the degree of
darkening at the 1hr 10min point which made me abort the reaction and work-up at this time.
In-spite of this, greater than 80% yields was obtained of the nitroethene after recrystallization from IPA.
A similar short time was needed for the 5-Ethoxy homologue.
The corresponding 'nitropropenes' can prepared in high yield at room temperature with a cyclohexylamine catalyst with no AcOH present.
Attempts to use nitromethane and cyclohexylamine for 4-(n)-propylthio-2,5-dimethoxybenzaldehyde and 4-ethyl-2,5-dimethoxybenzaldehyde at room
temperature gave gunk.
I think you have "over-cooked" this one.
--
The ammonium acetate used was prepared from bubbling NH3 gas into a AcOH/IPA solution and had some residual AcOH present.
The MeNO2 was distilled from "glow fuel" brand name "cool power".
These reagents have given similar results when used on other substrates compared to their counterparts obtained from laboratory suppliers.
[Edited on 9-8-2014 by Scr0t]
SweetHomeSunscreen - 8-8-2014 at 21:16
Many thanks, yes I believe I 'overcooked' it too. I dissolved the orange microcrystals in DCM and left it to evaporate in a tall container. I was left
with a gradient of impurities, with the fluorescent orange needles I had imagined at the bottom. Brown gunk at the top. I too noticed the reaction
colour reaching a dark orange very quickly (only an hour or so at RT!), should have pulled it shortly after!
Sadly these crystals only weighed 2g. The middle layer should be salvageable.
Solo, it's a pleasure to see you! Read many, many of your posts over the years! 