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Author: Subject: Piperazine workup
njl
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[*] posted on 17-5-2020 at 10:50
Piperazine workup


Hi all. After doing some reading on the use of amines as proton sponges, I thought I'd try a typical reaction using one. I happen to have a bunch of vanillin, so I went ahead and used the erowid demethylation procedure with pyridine as a scavenger. To be brief, I began to wonder if piperidine or piperazine would work better as scavengers due to both being saturated rings and piperazine having a second nitrogen. I got a good deal for piperazine-based deworming medication on ebay. I later received two bottles of piperazine citrate in water with a bunch of sugars and preservatives which I obviously don't want. The plan was to freebase the piperazine and then distill, but unfortunately my condenser just died. Is there any other way to separate the freebase from the aqueous solution (i.e. an insoluble adduct or alternative solvent)?
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mackolol
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[*] posted on 18-5-2020 at 00:11


It's very hard to separate such mixtures without distillation. All I can suggest you is to buy new condenser and try to distill it, You'll need the condenser anyways.
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draculic acid69
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[*] posted on 18-5-2020 at 00:42


You can extract the alkaline mixture with a non polar and then dry it and gas it if u r after the HCL salt
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karlos³
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[*] posted on 18-5-2020 at 04:02


Pyridine is more than just acid scavenger in that reaction.
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unionised
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[*] posted on 18-5-2020 at 09:27


The aldehyde group will react with the secondary amines.
If you had dimethyl piperazine it would be interesting.
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G-Coupled
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[*] posted on 18-5-2020 at 10:10


Quote: Originally posted by karlos³  
Pyridine is more than just acid scavenger in that reaction.


How so? Catalyst?

Quote: Originally posted by unionised  
If you had dimethyl piperazine it would be interesting.


Why's that, as a matter of interest?
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arkoma
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[*] posted on 22-5-2020 at 09:49


so does anyone have a definite answer on pulling the base from wormer?


*edit* Arkoma is gonna get off his lazy ass and do some experimental.

[Edited on 5-22-2020 by arkoma]




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karlos³
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[*] posted on 22-5-2020 at 10:19


Quote: Originally posted by G-Coupled  
Quote: Originally posted by karlos³  
Pyridine is more than just acid scavenger in that reaction.


How so? Catalyst?

Pyridine, but only as it forms one of its hydrohalogenide salts by reaction with the dry aluminium salt, is the active demethylating reagent, as far as I understood it.
We all know how pyridine HCl is used for that purpose, I understand it like that it will form in-situ, and thus be the responsible reagent to result in that reaction.

I doubt it can be replaced with either piperazine or piperidine.
As far as I know, it has something to do with pyridine being a tertiary amine and won't work with those two secondary ones.
On the other hand, it will work with triethylamine instead, but just worse.

Good luck with the piperazine isolation!
I read it is quite annoying and not easy.
But as soon as you have the dihydrochloride salt, treat it carefully.
When you prepare the monohydrochloride for a monoalky-/acylation, you should really take care to get the other molar half that acts as acid scavenger during that process out afterwards.
It will precipitate as diprotonated salt after the reaction under cooling, so filter that and keep it for later reactions on hand.
Without using any other base as acid scavenger, the piperazine itself will fill in that purpose.
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