Question

Do diastereoisomers have the same `R_f` values?

Answer 1

Absolutely not.

Explanation:

The `R_f` values may be similar, they may even be the same; however, there is no a priori reason that they should be equal. Diastereomers are different compounds with different chemical and physical properties. If we were to use a non chiral chromatographic column we would expect to get some degree of separation. The actual process of separating diastereomers is tedious in the extreme. Drug analyses and pharmacology demand these separations.