Which, 9-fluorenol or 9-fluorenone, would have higher Rf value on a silica gel plate with 30% acetone/70% hexane at the eluent? Explain.
i think it is 9-fluorenol
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 consider their chemical properties and interactions with the solvent and stationary phase.
Rf (retention factor) is a measure of how far a compound moved on a chromatography plate relative to the solvent front. It is calculated by dividing the distance traveled by the compound by the distance traveled by the solvent front.
In this case, the eluent is a mixture of acetone and hexane, with acetone being more polar than hexane. Silica gel is a polar stationary phase. To predict the Rf values, we need to consider the relative polarities of the compounds and the solvent.
9-fluorenol is an alcohol compound, which contains the -OH functional group. Alcohols are generally more polar than ketones like 9-fluorenone. The presence of the hydroxyl group in 9-fluorenol enhances its polarity, making it more soluble in the polar solvent (acetone) and interact more with the polar stationary phase (silica gel). Therefore, 9-fluorenol would likely have a lower Rf value because it would travel a shorter distance on the chromatography plate compared to the solvent front.
On the other hand, 9-fluorenone lacks the hydroxyl group, making it less polar than 9-fluorenol. Due to its reduced polarity, 9-fluorenone is expected to be less soluble in the polar solvent (acetone) and interact less with the polar stationary phase (silica gel). As a result, 9-fluorenone would likely have a higher Rf value and move further along the chromatography plate compared to the solvent front.
In summary, based on the relative polarities of the compounds and the polarity of the eluent and stationary phase, 9-fluorenol would have a lower Rf value, while 9-fluorenone would have a higher Rf value on a silica gel plate with 30% acetone/70% hexane as the eluent.