Q#1: I want to run a TLC on my 3 purified compounds: (1) 1,4-dibromobenzene (2)
ID: 229064 • Letter: Q
Question
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.
Explanation / Answer
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.
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