Q1 I want to run a TLC on my 3 purified compounds 1 14dibrom

Q#1: I want to run a TLC on my 3 purified compounds: (1) 1,4-dibromobenzene (2) methyl 4-amnobenzoate (3) 2-chlorobenzoic acid. Which would be a better mobile phase (solvent) to run my Thin layer chromatography (NOT column chromatography). Also I\'d like to say that the reagants given in the lab are strictly: methanol, ethanol, methylene chloride, hexane, 1M NaOH, 6M NaOH, 1M HCl, 6M HCl, Anhydrous sodium sulfate, saturated sodium chloride, acetone, sodium bicarbonate, diethyl ether. I do not have access to other reagants to use.

a) Using methylene chloride + methanol (and if yes, what % ratios?) or…

b) 70% hexane + 30% acetone

c) or do you have another better suggested pairing of solvents?

Q#2: Because I have solid compounds, I know that I need to dissolve my solid sample for spotting on my TLC plate. Which would be a good volatile solvent to do so (a) acetone? Or (b) methylene chloride? Both were suggested in the back of my lab manual. I was wondering if there was one better than the other.

Solution

a) For your TLC solvents, you can better use Hexane and Dichloromethane solvents. secondly, the ratio depends on the Rf value of the compounds. Start with 10% dichloromethane and 90% hexane and check if this solvent ratio is giving better separation of the compounds. If this does not work out, try increasing the polarity to 15% dichloromethane and 85% hexane. you can gradually increase the polarity of the dichloromethane depending on the extent of separation of your compounds.

b) use dichloromethane for dissolving your solid samples.