Compound A has an R_f of 0.8 on an alumina gel TLC plate. Compound B has an Rf o

Question

Compound A has an R_f of 0.8 on an alumina gel TLC plate. Compound B has an Rf of 0.6 on the same TLC plate. If a mixture of Compound A and Compound B was eluted through an alumina gel column, which compound would elute first? Compound A Compound B They both would elute at the same time Ferrocene is non-polar and acetylferrocene is polar. If an alumina column was eluted with hexanes (non-polar), which compound would elute first? acetylferrocene both would elute at the same time ferrocene A rotary evaporator will evaporate a solvent at a temperature lower than the normal boiling point. Why? The system is at an increased pressure, which reduces the boiling point The rotary evaporator introduces water into the solvent, reducing the boiling point. The rotary evaporator removes water from the solvent, reducing the boiling point. The system is at a reduced pressure, which reduces the boiling point.

Explanation / Answer

Q.4

Retention factor (Rf) = Distance travelled by the compound on the TLC plate / Distance travelled by solvent front

Compound with the larger Rf is less polar because it interacts less strongly with the polar adsorbent on the TLC plate.

Rf of compound A (= 0.8) is higher than Rf of compound B (= 0.6). Hence we can say Compound A is less polar than compound B

Compound A being less polar will elute first through an alumina gel column. More polar compound B binds more tightly to alumina gel therefore elute will later.

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