Which, 9-fluorenol or 9-fluorenone, would have higher Rf value on a silica gel
place with 30% acetone/70% hexane as the eluent? Explain.
I would think the more polar molecule would be kept behind by the silica gel.
which one is more polar?????
What makes a molecule more polar?
A molecule iz made more polar due to the presence of hydrogen bonds; d more d bonds d more polar d molecule. Also, d more electrones available for desociation, d more polar d molecule.
To determine which compound, 9-fluorenol or 9-fluorenone, would have a higher Rf value on a silica gel plate with 30% acetone/70% hexane as the eluent, we need to understand the factors that influence the Rf value.
The Rf value is a measure of the compound's migration distance relative to the migration distance of the solvent. It is calculated as the ratio of the distance traveled by the compound spot to the distance traveled by the solvent front.
In this case, the eluent is a mixture of 30% acetone and 70% hexane. The polar acetone component will have a stronger affinity for the polar silica gel compared to the nonpolar hexane component.
9-fluorenol is a polar compound due to the presence of the hydroxyl group (OH) which can form hydrogen bonds. On the other hand, 9-fluorenone does not have any polar functional groups and is relatively nonpolar.
Since the eluent contains a significant amount of nonpolar hexane, which has a weaker affinity for silica gel, 9-fluorenone, being less polar, will have a higher tendency to dissolve in the eluent and migrate more effectively up the plate.
On the other hand, the polar 9-fluorenol will have a stronger affinity for the silica gel and will be less soluble in the nonpolar eluent, resulting in slower migration up the plate.
Taking these factors into consideration, 9-fluorenone is expected to have a higher Rf value compared to 9-fluorenol on a silica gel plate with 30% acetone/70% hexane as the eluent.