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Author: Subject: How to get rid of last nitromethane in methanol
Σldritch
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[*] posted on 9-6-2019 at 10:15
How to get rid of last nitromethane in methanol


My methanol has a slight nitromethane contamination, how can i get rid of it?
I have already tried distilling it from hydrochloric acid and Sodium Hydroxide but it still turns yellow on standing.
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SWIM
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Mood: feeling a little stiff after that 2,4,5 trioxin exposure.

[*] posted on 9-6-2019 at 10:56


I wonder if the Nitromethane could be reduced before distillation, like with HCl and zinc or tin or even iron, or with ferrous sulfate.

Or perhaps adsorbed on activated carbon?





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unionised
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[*] posted on 9-6-2019 at 11:32


Isn't the azeotropic distillation good enough to get rid of it?
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Σldritch
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[*] posted on 10-6-2019 at 02:01


SWIM: Reducing it is a good idea but the problem finding a cheap enough reducing agent since i really do not want to waste nice ones on methanol. Metal/HCl seems like the best option since it should trap all the formed methylamine reducing the number of required distillations.

unionised: Assuming you mean fractional distillation; it does not work since it forms a 9% nitromethane azeotrope. Its a lot of lost nitromethane, i tried getting a use out of it by converting it to Hydroxylammonium Chloride and formic acid but i did not get any product.
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monolithic
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[*] posted on 10-6-2019 at 03:35


Be careful with NaOH and nitromethane.

http://www.sciencemadness.org/talk/viewthread.php?tid=5026&a...

http://reag.paperplane.io/00002099.htm

[Edited on 10-6-2019 by monolithic]
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lordcookies24
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[*] posted on 10-6-2019 at 07:35


Methanol has a boiling point 40*C lower than nitromethane. Can’t you just distill it?
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[*] posted on 10-6-2019 at 10:54


Quote: Originally posted by Σldritch  
S

unionised: Assuming you mean fractional distillation; it does not work since it forms a 9% nitromethane azeotrope. Its a lot of lost nitromethane, .

I mean azeotropic distillation.
You can distill out the azeotrope which, as you say contains 9% nitromethane.
You said at the outset that "My methanol has a slight nitromethane contamination,"
If the quantity of nitromethane is small then you only lose about 11 times as much methanol as nitromethane.

Even if there's enough nitromethane for that to be a significant loss, it's still worth a try for two reasons.
You should be able to get some clean methanol and it's more efficient to try to destroy the nitromethane if there's less methanol "in the way".

Reduction with something like steel wool and HCl seems a cheap option.
I'd not recommend the use of alkali- especially not with distillation.
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Σldritch
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[*] posted on 14-6-2019 at 05:29


I see, problem is i do not actually know how much nitromethane is in the methanol but judging from how yellow it is compared to my nitromethane that has stood next to it in storage it is several percent and separating out the azeotrope would probably lead to a great loss of methanol. I think i will try the iron/HCl sometime.
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