Calculate the Rf values for the following compounds. (a) Spot, ...

[Haya94]

Calculate the Rf values for the following compounds.
  (a) Spot, 5.0 cm; solvent front, 20.0 cm
  (b) Spot, 3.0 cm; solvent front, 12.0 cm
  (c) Spot, 9.8 cm; solvent front, 12.0 cm

Question 2

The Rf values determined on silica gel TLC plates for Compounds A, B, and C are tabulated in
  Table 11.5.
  (a) In order to purify Compound A, which of the solvent systems should be used to develop
  the column in a flash chromatography procedure?
  (b) Could 90 mg of a mixture of Compound A and Compound B be separated by macroscale
  flash column chromatography using 20 ethyl acetate80 hexanes as the eluting sol
  vent?
  (c) Could 90 mg of a mixture of Compound A and Compound C be separated by macroscale
  flash column chromatography using 20 ethyl acetate80 hexanes as the eluting sol
  vent?

[chinwesucks]

Answer to Question 1

(a) Rf = 5.0 cm/20.0 cm = 0.25
(b) 0.25
(c) 0.82

Answer to Question 2

(a) 20 ethyl acetate80 hexanes
(b) Only if a column greater than 10 mm is used, because the difference in their Rf values is
0.05, and must be >.20 to be separated in a flash chromatography procedure if 90 mg is
applied to the column.
(c) Only if a column greater than 10 mm is used, although if only 40 mg is applied to the col
umn, they could be separated.

[Haya94]

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[chinwesucks]

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