[Messi]

how long does a column chromatography take?

[discodermolide]

Depends upon the separation you are seeing on TLC.
When you are good at it it takes about 30-60 minutes, as I said though if you have a lousy separation on TLC it can take longer.
The longest time it took me was 12 hours but that was with 40kg of silica reverse phase.

[PhDoc]

Funny. I remember having a column go past 2 hours once. The stuff still didn't elute, so I called it a night. When I came back the next morning, I collected more fractions and realized the next step of my synthetic sequence had been completed overnight!

Are you using isocratic or gradient elution methods? I've always used gradient elution, and for the most part never had chromatography go beyond 1 hour (with the exception noted).

As already pointed out, you can expect the time to increase with increasing scale.

[Messi]

I only have a small scale with 0.23mL of product.

[discodermolide]

You need to make sure your solvent system is OK by checking TLCs of the material. Try and get the maximum separation of all the components. With such a small amount of sample the chromatography should not take very long.

[Messi]

You need to make sure your solvent system is OK by checking TLCs of the material. Try and get the maximum separation of all the components. With such a small amount of sample the chromatography should not take very long.

Excellent, will do!

[orgopete]

how long does a column chromatography take?

Look up flash chromatography.

[fledarmus]

It depends on the R_f of your spot, the volume of silica gel in your column, and the speed at which you are pumping the solvent through. Very roughly, if the characteristics of your TLC plate and your column silica match pretty well, you can assume that each column volume pumped through the column will elute your spot by the R_f you see on the TLC plate. So if your R_f is 0.1, you will need to pump through 10 column volumes of the same solvent to elute the spot. If your column volume is 50 mL, and your pump speed is 20 mL/min, you will pump one column volume of solvent in 2.5 minutes. (Another helpful rule of thumb is that 2 mL of silica gel is about 1 gm).

It never works out quite that nicely and you will probably be using gradients anyway (if you have an automated system), but it does give you a starting point to work with.