These questions are in the 4th edition of the Handbook for Organic Chemistry Lab. Once you've tried them on your own, click on the link at the bottom of the page to view the answers.
1) You want to separate compound A from compound B by flash chromatography. The following are the results of running these two compounds in different hexanes/ethyl acetate systems. Which is the best solvent system to elute compound A? Compound B?
2) The following two solvent systems were found to separate compounds X and Y by flash chromatography:
Which is the more polar compound, X or Y?
3) In order to separate a mixture of X and Y as in problem (2) by column chromatography:
4) A student loaded a mixture onto a small flash chromatography column in 1 mL of methylene chloride, then proceeded to elute with hexanes/ethyl acetate 10:1. He/she found that all of the mixture came off in the first 4 fractions, with no separation. What technical mistake did the student make?
5) You only see one compound coming off the column when you suspect two. Where might the other compound be? How can you recover this compound?
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