possible, but should be your goal when running a TLC.(For column chromatography the correct solvent system should give an Rf between 0.2 and 0.3. Now, which solvents to pick? Here is a list of some standard solvents and their relative polarity (from LLP) Very polar additives Methanol >Ethanol>Isopropanol Moderately polar additives: Acetonitrile Ethyl Acetate >Chloroform> Dichloromethane > Diethyl Ether> Toluene Non-polar additives: lohexane. Petroleum Ether. Hexane. Pentane Common solvent combinations Ethyl Acetate/Hexane: 0-30%0 most popular combination, sometimes tough to remove solvents completely on rotary evaporator Ether/Pentane: 0-40% very popular, easy to remove on the rotary evaporator Ethanol/Hexane or Pentane: 5-30% useful for very polar compound Dichloromethane/ Hexane or pentane:5-30% sometimes useful when other mixtures fail 3)Fill tLC chamber with 1-2 mL of the desired solvent system. Place a large piece of cut filter paper in the chamber as well 4)Spot the compound on the baseline of the tlc plate We will use commercial spotters, but spotters can be pulled from hot Pasteur pipets (you may see this in your UROP). If you are monitoring a reaction, make sure to spot the starting material, the reaction mixture, and a co-spot of both 5)Run the TLC. Let the solvent go about 90% of the way up the plate 6)Remove the plate from the chamber and mark the solvent front immediately with a pencil. You will use this to calculate the rf 7) Let the solvent dry off of the plate. 8)Visualize the tlC using non-destructive technique(s). The best non-destructive method is the UV lamp. Place your plate under the UV lamp and circle any UV active spots with your pencil. Although we won't do this in 5.301, another popular non-destructive method is staining with iodine. (You might see this in your UROP)possible, but should be your goal when running a TLC. (For column chromatography the correct solvent system should give an Rf between 0.2 and 0.3.) Now, which solvents to pick? Here is a list of some standard solvents and their relative polarity (from LLP): Very polar additives: Methanol > Ethanol > Isopropanol Moderately polar additives: Acetonitrile > Ethyl Acetate > Chloroform > Dichloromethane > Diethyl Ether > Toluene Non-polar additives: Cyclohexane, Petroleum Ether, Hexane, Pentane Common solvent combinations: Ethyl Acetate/Hexane : 0–30% most popular combination, sometimes tough to remove solvents completely on rotary evaporator Ether/Pentane: 0–40% very popular, easy to remove on the rotary evaporator Ethanol/Hexane or Pentane: 5–30% useful for very polar compounds Dichloromethane/Hexane or Pentane : 5–30% sometimes useful when other mixtures fail 3) Fill TLC chamber with 1–2 mL of the desired solvent system. Place a large piece of cut filter paper in the chamber as well. 4) Spot the compound on the baseline of the TLC plate. We will use commercial spotters, but spotters can be pulled from hot Pasteur pipets (you may see this in your UROP). If you are monitoring a reaction, make sure to spot the starting material, the reaction mixture, and a co-spot of both. 5) Run the TLC. Let the solvent go about 90% of the way up the plate. 6) Remove the plate from the chamber and mark the solvent front immediately with a pencil. You will use this to calculate the Rf. 7) Let the solvent dry off of the plate. 8) Visualize the TLC using non-destructive technique(s). The best non-destructive method is the UV lamp. Place your plate under the UV lamp and circle any UV active spots with your pencil. Although we won't do this in 5.301, another popular non-destructive method is staining with iodine. (You might see this in your UROP.) 48