Thin‑Layer Chromatography

1. Take a few crystals of the 4-nitrobromobenzene isomer, place in a 5 ml beaker, and add 10 drops of chloroform  to the beaker to dissolve the crystals.

2.  Take a 2.5 x 7.5 cm strip of silica gel, mark the origin 1 cm from bottom and make 2 pencil marks lightly on the origin.

3.  Apply one drop of the solution containing the 4-nitro isomer on one spot & one drop of oil containing the 2-nitro isomer on the other spot.  Be sure that neither application results in a spot more than 2 mm in diameter.  Allow the strip to dry at your hood workstation .

4. Place dried strip in jar containing the solvent solution Hexane: Chloroform 9:1.

5.  When the solvent system reaches  within 1 cm of the top of the strip, remove the strip, allow to dry at your hood workstation & view under ultraviolet light in the U.V. box.  Outline the spots with a pencil by stippling around each spot while the chromatogram is still in the U.V. box.

6.  Put the rest of the oil,  in the beaker, into the jar provided in the hood & place your 4-nitro solid jar on the tray provided.

Again, before you leave, wash down your benchtop with 95% ethanol in the same fashion as yesterday.