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Author: Subject: First o-toluidine synthesis - running into some issues with the reaction mixture
SuperOxide
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[*] posted on 24-5-2021 at 09:31


Quote: Originally posted by Fery  
see this, in the reduction of aromatic -NO2 to -NH2 using Fe+HCl the HCl seems to be there only as a catalyst which activates Fe
https://sci-hub.st/10.1021/ja01238a049
https://sci-hub.st/10.1002/adsc.200404236

Thanks! I thought about using Fe instead of Sn, but from what I hear it's a nightmare of a cleanup with no better of a yield. Is that not the case? I mean the tin was a bit more expensive than I thought, but I saved everything from the toluidine runs and plan on getting the tin back out of it - someday, lol.

Quote: Originally posted by Amos  
Just now saw your most recent posts, SuperOxide, congrats on a job well-done. There is almost certainly excess DCM in your o-toluidine but I feel as though in many reactions it will simply spectate.
I ended up doing a vacuum short path distillation to get nice pure toluidine, worked like a charm, though I only had a shitty hot plate and a hand pump vacuum thingy but I still lowered the bp from 200 °C to 141 °C, which was pretty good. But for some reason, even though the hot plate was cranked on high and the contents were still boiling, it wasn't enough to get it all up to the still head. I attribute this to the fact that I had to use a 14/20 to 24/40 adapter, which added some distance to the still head (I did this because all my 24/40 RBBF's are too big, so I used a 100mL 14/20 RBBF (and I had to use a round bottom, because a flat bottom may break under vacuum with such heat)), and since it's a hot plate and a round bottom flask I had to use a sand bath, which sucks out a lot of heat.

Regardless, I was able to get a decent amount of crystal clear horse manure smelling toulidine :)

Quote: Originally posted by Amos  
My DCM is precious to me, and this method also has the advantage of not requiring a second distillation where unwanted mechanical losses and coloring of the product can occur.

I also consider my DCM precious, probably more so than any of my other solvents. I actually got 1L ACS grade anhydrous DCM off of Amazon over a year ago...

...and the price of the same listing has gone up over time. I recycle it every chance I get (and keep the recycled stuff in a separate container, so I know which is pure ACS grade and what is just distilled/dried).

Quote: Originally posted by Amos  
But as I said before, nice job on a good-looking product and respectable yield.
Thank you! It was a fun synthesis. I don't think I'll do it again in the near future, especially not with just this hotplate, as I know I'll run into some of the same distillation problems.


Also, I put all the purified, clear, oT in an amber flask and even purged the air out of it by spraying in some N2, then sealed it very well. Here are the containers:

(pure on the right, then what I couldn't get to distill over is on the left, and since I heated it up so much in the distillation it went much darker, but was still usable - Here's a video of it that I can't embed).
But despite being in an amber bottle, very well sealed and over N2... It still slightly degraded, somehow :(:

That was about 2 months or so. I guess maybe I didn't get all the O2 out of it? Very surprising though, I was sure I did.

[Edited on 24-5-2021 by SuperOxide]




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