column chromatography

Question

I recently did a column chromatography lab for organic chemistry and I wanted some help to see why I got weird results. My column had a alumina stationary phase and we were separating fluorene and fluorenone. After some research I found out that fluorene is supposed to elute first but when I did my experiment, fluorenone eluted first (the yellow color was obvious). and I also got very little of the fluorene. what may have happened? just human error?

Answer 1

Human error is always possible but there are possible reasons for the results. If you separating a fluorine/fluorenone mixture that was mixed in the academic lab, it is possible the solution was not prepared properly and ended up with little fluorene.

Another issue is to make sure you used the correct mobile phases. If you used 30% acetone in hexane instead of just hexane, you would see the fluorenone.