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Topic: debenzylaton?  (Read 13290 times)

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Offline sw2672

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debenzylaton?
« on: August 27, 2006, 06:41:10 PM »
I am trying to do debenzylation from N-benzyl materials. I used palladium on carbon which I purchased from Aldrich.  However, I did not get anyl desired product. No reaction.. Is there any way to check out the activity of palladium?  or What's wrong with my reaction? please help me.

Offline Beaker10

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Re: debenzylaton?
« Reply #1 on: August 28, 2006, 12:16:16 AM »
What pressure of hydrogen are you using?  You can use PtO2 as a catalyst as well as Pd/C.  Also you can use 10% Pd/C or PtO2 as catalyst and substitute H2 gas with xs ammonium formate (10 equiv) in refluxing EtOH...Hope these suggestions help...

Offline movies

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Re: debenzylaton?
« Reply #2 on: September 05, 2006, 11:16:11 PM »
You could try out you Pd/C on some other compound where debenzylation conditions are known already.  Other methods are out there for cleaving Bn groups as well, but that depends on what else is in your molecule.

Offline bontempo

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Re: debenzylaton?
« Reply #3 on: September 26, 2006, 05:32:32 AM »
A friend of mine had the same problem, sometimes those N-Bn won't come off. He then tried the Na/NH3 procedure - it was waaay less complicated than it seems and the deprotection was finished in no-time (his molecule was rather functionalised and there was an indole ring present). Plus it helped demistify reactions run in liquid nitrogen here in the lab  ;D

Offline sa1chavez

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Re: debenzylaton?
« Reply #4 on: August 06, 2007, 09:02:54 PM »
you can also try adding a little acetic acid to your reaction

Offline Custos

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Re: debenzylaton?
« Reply #5 on: August 08, 2007, 07:55:14 PM »
A friend of mine had the same problem, sometimes those N-Bn won't come off. He then tried the Na/NH3 procedure - it was waaay less complicated than it seems and the deprotection was finished in no-time (his molecule was rather functionalised and there was an indole ring present). Plus it helped demistify reactions run in liquid nitrogen here in the lab  ;D
;D Liquid ammonia, right? I've never thought of using liquid nitrogen as a solvent.  :o

Offline wintermute

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Re: debenzylaton?
« Reply #6 on: September 15, 2007, 03:34:55 AM »
closely related question: how do you clean stirring bar from charcoal?

Offline movies

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Re: debenzylaton?
« Reply #7 on: September 27, 2007, 01:29:37 PM »
Charcoal is a pain.

Try stirring in aqua regia (~1:1 mix of conc HNO3 and conc HCl) for a few hours.  Be careful, it's nasty stuff.

Offline wintermute

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Re: debenzylaton?
« Reply #8 on: October 11, 2007, 12:13:39 PM »
stirring in aqua regia had no effect :)

Offline Sharkie

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Re: debenzylaton?
« Reply #9 on: October 21, 2007, 04:48:02 PM »
Else try stirring with Piranha. Although heavy caution must be taken with this as it's highly corrosive and potentially explosive if it contacts with organic solvents, but it's damn good for cleaning when care is taken (add little at a time with a glass pipette). Not sure if I can post the recipe though as I'm new to these forums and it might violate the forum rules?

Offline stimulusartifact

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Re: debenzylaton?
« Reply #10 on: October 31, 2007, 02:24:46 AM »
I am very new to chemistry, so pardon my candor. 

I noticed that when using a par apparatus, you can see the H2 pressure decrease as your catalyst binds hydrogen.  I guess if the pressure drop for a solution with catalyst is greater than the pressure drop for ~the same volume solution without, then your catalyst is binding hydrogen.  I guess ideally you could see if your solvent bursts into flames (especially if you are using methanol).  My advisor also told me about "Palladium black", which you can purchase from Aldrich..  but use it with argon.

Offline trufalup

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Re: debenzylaton?
« Reply #11 on: December 17, 2007, 02:04:05 AM »
Check into Formic acid (ammonium formate) and Pd.

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