Arrange the following 4 compounds in the order of their elution from a silica pl

Question

Arrange the following 4 compounds in the order of their elution from a silica plate using benzene as eluent.

(a) CH3CH2CH2CH2CH2CH3 (b) CH3CO2H (c) CH3CH2OH (d) CH3COCH2CH3

A compound (caffeine) is applied to the silica TLC plate and developed using dichloromethane as a solvent. The anaylsis of the results suggest that the compound didn't move from the origin and has zero Rf.

Which of the following 4 solvents would you try to increase the Rf? May have multiple answers.

(a) hexane (b)toluene (c) CH3CH2OH (d) CH3COCH2CH3

Explanation / Answer

caffeine is a polar compound so non polar solvents like hexane or toluene will not work. It is necessary to use more polar solvent like MeOH or EtOH, best possibility to use combination of MeOH or EtOH with dicholoromethane. Since silica gel can dissolve in MeOH or EtOH alone. Best combination is MeOH/dicholoromethane.

I saying from my practical experience

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