[sambasivarao]

i wnat do reduction with palladium catalyst what is the procedure for that? is it have to do in autoclave?

[Dan]

Do you mean catalytic hydrogenation with a Pd on charcoal catalyst?

There are tons of papers with preps for this reaction.

I have done this reaction several times to convert R-I --> R-H

I tend to use 10-15% by mass (of substrate) of 10%Pd on C (ie. 1-1.5% Pd by mass).
Degas your solution under Ar.
Stir under hydrogen.
Do not let oxygen (ie. air) into your reaction vessel if hydrogen is present, it's dangerous.
Solvent: Ethanol

[movies]

This reaction works in lots of other solvents too, but alcohol solvents are usually the fastest.  I've always thought that EtOAc is a good starting point for solvent.

Be careful when you filter your reaction when it is finished.  Pd/C can sometimes ignite when exposed to oxygen, so try to avoid letting it dry out completely.

[Dan]

yes, and use a deep celite pad, the Pd/C will go straight through a sinter.

[Custos]

Do you mean catalytic hydrogenation with a Pd on charcoal catalyst?

There are tons of papers with preps for this reaction.

I have done this reaction several times to convert R-I --> R-H

(pedantic alert!) The reaction you describe is strictly a hydrogenolysis, not hydrogenation. Hydrogenation is addition of hydrogen across, for example, a carbon-carbon double bond.

I'll never forget this because a colleague of mine had used "hydrogenation" instead of "hydrogenolysis" throughout a PhD thesis and one of his examiners picked him up on it. This was in the 1970's so pre-wordprocessors, and he had to have the entire thesis retyped correcting the word hundreds of times.

[Dan]

Ha, thanks for the heads up, I'm going to start writing my masters thesis soon.
Makes sense, since you have hydrogenolysis of Bn groups etc.

[pantone159]

P.S.  What is the proper disposal method for pyrophoric metal catalysts like Pd, Raney Ni, etc.
My books say to always keep them covered in water, but that seems hard to do forever (unless you dump them in the ocean!)

[DaveD]

I would imagine proper disposal of precious metal catalysts would be handled by hazardous waste technicians at your institution.  These catalysts are usually recycled (since they are precious).  And you are correct, they should be stored under water.

One other suggestion - water wet palladium on carbon catalysts are usually much less prone to the ingition risk mentioned by movies.  (I've had a number of small fires on the filter when filtering of dry palladium on carbon catalyst from organic solvent, but not when using water wet palladium on carbon catalyst).

[movies]

(pedantic alert!) The reaction you describe is strictly a hydrogenolysis, not hydrogenation. Hydrogenation is addition of hydrogen across, for example, a carbon-carbon double bond.

Ohh!  Nice catch!