| Pages:
1
2 |
Happyer
Harmless
Posts: 8
Registered: 23-12-2009
Member Is Offline
Mood: No Mood
|
|
Sorry i must have misread that. any other extraction solvents? DCM, Pet. Ether?
|
|
|
Picric-A
National Hazard
Posts: 796
Registered: 1-5-2008
Location: England
Member Is Offline
Mood: Fuming
|
|
Anybody got a simple method of converting piperzine phosphate to piperazine monohydrochloride?
I had an idea, dissolve piperazine phosphate powder an alcoholic NaOH, causing sodium phosphate to precipitate and leaving piperazine in alcoholic
solution. feasable?
Thanks
[Edited on 17-3-2010 by Picric-A]
|
|
|
Picric-A
National Hazard
Posts: 796
Registered: 1-5-2008
Location: England
Member Is Offline
Mood: Fuming
|
|
I have left over benzyl chloride form my local anasthetic prep and i thought i could make some 1-benzyl chloride.
Looking at org syn the prep:
| Quote: |
A solution of 24.3 g. (0.125 mole) of piperazine hexahydrate in 50 ml. of absolute ethanol,
contained in a 250-ml. Erlenmeyer flask, is warmed in a bath at 65° as there is dissolved in the solution,
by swirling, 22.1 g. (0.125 mole) of piperazine dihydrochloride monohydrate (Note 1). As warming in
the bath at 65° is continued, there is added during 5 minutes, with vigorous swirling or stirring, 15.8 g.
(14.3 ml., 0.125 mole) of recently distilled benzyl chloride. The separation of white needles commences
almost immediately. After the solution has been stirred for an additional 25 minutes at 65°, it is cooled,
and the unstirred solution is kept in an ice bath for about 30 minutes. The crystals of piperazine
dihydrochloride monohydrate are collected by suction filtration, washed with three 10-ml. portions of
ice-cold absolute ethanol, and then dried. Recovery of the dihydrochloride is 21.5–22.0 g. (97–99%)
(Note 2).
The combined filtrate and washings from the piperazine dihydrochloride are cooled in an ice bath
and treated with 25 ml. of absolute ethanol saturated at 0° with dry hydrogen chloride (Note 3). After
the solution has been well mixed, it is cooled for 10–15 minutes in an ice bath. The precipitated white
plates of 1-benzylpiperazine dihydrochloride are collected by suction filtration, washed with dry
benzene, and dried. The product, which melts at about 280° with decomposition, after sintering at about
254° (Note 4), amounts to 29.0–29.5 g. (93–95%). A solution of this salt in 50 ml. of water is made
alkaline (pH > 12) with about 60 ml. of 5N sodium hydroxide, then extracted twelve times with 20-ml.
portions (Note 5) of chloroform. The combined extracts are dried over anhydrous sodium sulfate, and
the pale-brown oil (Note 6) remaining after removal of solvent is distilled at reduced pressure in a
Claisen flask. The yield of pure 1-benzylpiperazine, b.p. 122–124°/2.5 mm., nD 1.5440–1.5450, is
14.3–16.5 g. (65–75%).
|
This is realy confusing as it says add 22.1g of piperazine dihydrochloride but then later on it says filter it out! :O is it a catalyst or something?
if not can i just miss this out?
So my question is why cant you just add piperazine and benzyl chloride, what the point of the piperazine dihydrochloride and transforming the
piperazine to the monohdrochloride? Surly if you use piperazine base you are left only with 1-benzylpiperazine monohydrochloride?
This is a lot more simple, why over-complicate it?
|
|
|
DJF90
International Hazard
Posts: 2266
Registered: 15-12-2007
Location: At the bench
Member Is Offline
Mood: No Mood
|
|
Making 1-benzyl chloride from benzyl chloride?! What kind of jibberish is that? Now, if I'm thinking correctly, the piperazine reacts with the
piperazine dihydrochloride to form piperazine monohydrochloride (which is a mono-protected piperazine), half of which reacts with the benzyl chloride
making your benzylated piperazine (I am assuming this is what you want...) and piperazine dihydrochloride.
If you use piperazine itself, you can get dibenzylation as a strongly competing reaction. Forming the monohydrochloride by addition of acid to
piperazine does not work well; hence why they make it the way they do in situ.
For future reference, if something is added to the reaction mixture, its generally for a reason... Omitting it wouldn't be a wise move.
[Edited on 18-3-2010 by DJF90]
|
|
|
Picric-A
National Hazard
Posts: 796
Registered: 1-5-2008
Location: England
Member Is Offline
Mood: Fuming
|
|
If piperazine does not work why does the monohydrochloride not work on its own, surly this leaves one NH group open to attack, the other being
protected.
ie, start with the monohydrochloride
[Edited on 18-3-2010 by Picric-A]
|
|
|
Satan
Hazard to Others
Posts: 126
Registered: 1-5-2009
Member Is Offline
Mood: No Mood
|
|
It works, that synthesis you pasted is all about it. Maybe you should read it, and don`t trash topic about useful reagent, useful for other things
than drugs with questionable value.
|
|
|
turd
National Hazard
Posts: 800
Registered: 5-3-2006
Member Is Offline
Mood: No Mood
|
|
Well, there is HCl generated during the reaction and the dihydrochloride is insoluble in the reaction mix. That's why you need two molar equivalents
of the monohydrochloride. At least that's what I read out of this page:
http://www.erowid.org/archive/rhodium/chemistry/bzp.html
|
|
|
DJF90
International Hazard
Posts: 2266
Registered: 15-12-2007
Location: At the bench
Member Is Offline
Mood: No Mood
|
|
What I remember reading was that piperazine, when titrated with one equivalent of hydrochloric acid, forms a product of questionable composition. By
forming the dihydrochloride, and mixing this with stoichiometric piperazine, then the monohydrochloride is formed as expected.
|
|
|
Picric-A
National Hazard
Posts: 796
Registered: 1-5-2008
Location: England
Member Is Offline
Mood: Fuming
|
|
What about alkylating piperazine hydrogen phosphate (available as Pripsen pipereazine phosphate powder)
Surely this will yield 1-benzylpiperazine hydrochloride and phosphoric acid?
|
|
|
DJF90
International Hazard
Posts: 2266
Registered: 15-12-2007
Location: At the bench
Member Is Offline
Mood: No Mood
|
|
I doubt so, as the hydrogen phosphate would require both nitrogens to be protonated, by definition. Therefore they would both be protected. An
additional issue with polyprotic acids is that the salts change constitution depending on pH...
|
|
|
| Pages:
1
2 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
