Question

After performing a TLC experiment, a student was surprised to find that the plate appear blank under a UV light. The instructor suggested dipping the plate in chemical reagent, and samples suddenly appeared as bright pink spots.

A) what might account for this result?

B) What does this suggest about the reliability of using only one visualization method ( such as exposure of UV light) to interpret the results of a TLC experiment.

Explain detailed please.

Ps Chromatography

Answer 1

compounds which are having conjugated double bond system only can appear in the UV light

suppose you are doing the reactions with aliphatic saturtaed system here there is no any conjugated system

that time you cant see spots in TLC plate

that is the time you have to start use staining agents (chemical reagent)

let me take one exaple

i am oxidizing butyl alcohol in to butanaldehyde

CH3CH2CH2Ch2-OH ----> CH3CH2CH2CHo

here there is no any chromophore to show in UV light how you decide whether reaction finished

raise the TLC plate and then dip in KmNO4 solution

in KMnO4 both butanol and butaraldehyde will show spots