Question

TLC Experiment

Discuss the reason behind different Rf values of dyes by considerng chemical structures and possible interactions (like dipole-dipole, H bond, london forces etc.)

Rhodamine B - water Rf=0.039

Rhodamine B- ethanol Rf=0.3955

Rhodamine B- silica gel (discuss only interactions between them)

Amaranth O- water Rf=0.9555

Amaranth O- ethanol Rf=0.6455

Amaranth O- silica gel (discuss only interactions between them)

Answer 1

Interaction sof yes with solvent in tlc

Rhodamine B-water form strong H-bonding and this would lower tne Rf value.

Rhodamine B-Ethanol again forms hH-bonding that would reduce the Rf value

RhodmanineB-Silica gel : polar=polar iteractions, H-bonding between due asnd -OH of silica.

Amaranth O-water : Amaranth is non-polar and does not form H-bonding, shows lodon forces of attraction and thus Rf is high.

Amaranth O-ethanol : again shows weak london force of attraction slightly strognger then wht we found in water which is why Rf value is lower as less polar solvent ethanol than water.

Amaranth O-silica gel : would show, london disperson force of attraction and no strong other forces which would increase the Rf value.