[studytogether]

Why can't we use acetone as mobole phase when stationary phase is alumina?

I means what reaction in organic chemistry will happen so that can't we conbine as that?

thx for teaching

[JGK]

Alumina stationary phase is primarily used in Normal Phase Chromatography where the stationary phase is polar and the mobile phase is primarily non-polar.

Using acetone, a polar solvent with a polar stationary phase will negate the stationary phase retention capability you are trying to exploit.

[studytogether]

our textbook says that the alumina will have aldol condensation with acetone?

is it? I am not sure I have wrong memory or not..

[Rabn]

I think aldol condensation is just one reason. I am pretty sure the alumina would dissolve in the acetone. The alpha carbons on the acetone would lose H to the alumina...follow the dancing electrons and you'd aluminum hydroxide, alcohols, aldehydes.....and then you'd get the aldol condensation. The main reason though is that they don't want you to ruin the equipment. I don't think they care that much about the aldol condensation, it's the time it would take to replace and then season the equipment.

[JGK]

I couldn't find any references to Aldol Condensation on alumina columns in texts or web searches. I also failed to find much on acetone as a mobile phase component, probably due to its high UV absorbance at UV wavelengths.

As I said previousley, Alumina columns are primarily utilized in normal phase chromatography where the use of polar solvents would negate the separation effect.