Question

4. Consider the following silica gel TLC plac or compounds A, B, and hexines: developed in Fo-o- og a) Determine the Rr values of compounds A, B, and C run on a silica gel TLC plate using hexanes as the solvent b) Which compound, A, B, or C. is the most polar? values if you used acetone instead c) What would you expect to happen to the of hexanes as the eluting solvent? 5) Consider a sample that is a mixture composed of biphenyl, benzoic acid, and benzyl alcohol. The sample is spotted on a TLC plate and developed in a hexanes/ethyl acetate solvent mixture. Draw a sample TLC plate and predict the relative Rr values for the three compounds in the sample by labeling the spots with the compound names on your sample plate. 6a. Why should care be taken to insure that the top of the adsorbent on a column never dries out? b. Why should a mixture to be separated be introduced onto a column in a minimum amount of solvent?

Answer 1

ABC a) A Rf value = 0.2 BRf velue = 0.6 CRfvelu = o.s. Rf is to betwee o tol.. ided Rf is a 3 tool. - b) most polar is ta leant polar is - B • how a value polar. a high Rf voluet non polar. c) If we use a cetene instead of henang - The Rf values of all compounds AAC is increases, because acetone is more polar solvent han henane. 6 Benzyl alcholol) polarity ordere Benzoic acid> Biphenyl. Rf=0.9 9000006 T Siphenyl I benzoic acid Пm24. RE=0.6 O Aleaha CS Scanner Scanner witho. CamScartner