[Mocook]

Hello all,

This will be my first time attempting to run a dry packing column.

Can anyone with prior experience confirm the general procedure in prepping the column?

Does the dry silica(containing the sample) go directly over the moist silica and than sand is added?

After a reaction that yields several products, should i run it quickly through a mini-column to "clean it up" (what does that mean?) and than do a full column, or just go ahead and purify directly with a full column after the reaction?


Regards

[Dan]

Does the dry silica(containing the sample) go directly over the moist silica and than sand is added?

I usually pack the dry loaded silica with a bit of the weak solvent (normally hexane) before adding sand.

After a reaction that yields several products, should i run it quickly through a mini-column to "clean it up" (what does that mean?) and than do a full column, or just go ahead and purify directly with a full column after the reaction?

"Clean it up" is just lab slang for "purify it".
Normally would just aim to get everything out clean in a single column. The only reason I have planned to do two columns in series is on the rare occasion that I have a mixture of 3 things that I cannot separate using only one solvent combination.

e.g. a mixture of A, B and C showed this TLC behavior:

In EtOAc/hexane: R_f 0.40, 0.39, 0.30
In acetone/heaxane: R_f 0.50, 0.31, 0.30

In this case I chose to separate out A first with acetone/hexane and then separate B from C in a second column using EtOAc/hexane.