When performing thin layer chromatography (TLC) with a silica gel plate developed with dichloromethane as the solvent, the substances will separate based on their polarity and affinity to the stationary phase (silica gel) and the mobile phase (dichloromethane).
Naphthalene butyric acid is a relatively polar compound due to the carboxylic acid functional group, while phenyl acetate is less polar because it contains an ester group instead.
In this case, dichloromethane is a non-polar solvent. Generally, non-polar compounds travel farther up the TLC plate, while polar compounds adhere more strongly to the polar silica gel, resulting in lower movement.
Therefore, we would expect the order from top to bottom on the TLC plate to be:
- Phenyl acetate (farther up, less polar)
- Naphthalene butyric acid (lower, more polar)
This order results from the different polarities of the compounds and their interactions with the stationary and mobile phases during development.