[democanarchis]

Having a bit of a hard time scaling an experiment down. My substrate is reasonably difficult to make, so I don't want to commit more than a few hundred mgs to the trial run, which equates to a 0.5 mmol scale. The reaction is done in aqueous methanol, so that aspect isn't an issue. However, I can't get my head around weighing out 0.6 mmols of raney nickel. It's in a 50% aqueous slurry, but has mostly settled. Any procedures I've found mention weighing it by eye or in a graduated cylinder and estimating, but that won't work with 70mg of slurry. I was thinking properly agitate the solution and pipette it directly into the reaction vessel on a balance, but I don't want a pipette blowing air with raney nickel adhered inside. Ideas?

[OC pro]

I have used hundreds of mL´s of it. As long as it is in aqueous slurry it will not burn. You can simply take a 1ml syringe, take out about ~0.1ml and put it into a flask containing a stirring bar (magnetic). Then you add lets say 1ml methanol and for 10sec. The nickel will add to the stirring bar. Take most of the solvent out with the syringe, refill with fresh methanol. Stir for 10s and take it out again. Repeat this ca 5 times. This will remove the water which is actually a bit basic. Now you can add your aqueous methanol and proceed with the reaction.

You really need it in equimolar stoichiometry not catalytic?

[democanarchis]

Yeah, the paper has 1.2eq, its used with conc sulphuric acid to reduce a very stubborn N-benzyl (3 days at >20 bar H2 and 30% Pd(OH)2 didn't shift it)

Thanks for the suggestion, i'll give that a shot.

[Biorix]

Hi just a quick question regarding use of Raney Nickel Catalyst...What amount is effective for a reaction volume of say 1000ml and is this form of catalyst easily recoverable after reaction. I've read a number of articles regarding washing of the catalyst after use, is there a particular procedure for this.

[OC pro]

Depends on the scale and on the type of reaction. I can dissolve 100mg or 100g compound in 1000ml.
Removal of Raney-Ni afterwards is done by simple filtration over Celite and washing with methanol or ethyl acetate. Be aware of burning! Dry Raney-Ni ignites very nice.