Predicting NMR Signals with the Replacement Test

Proton chemical equivalence in ¹H NMR helps predict how many signals a molecule will show. Protons in the same electronic environment have the same chemical shift. The replacement test is a simple way to check whether protons are equivalent.

In the replacement test, a substituent is used to repla...

In a molecule, protons in identical electronic environments have the same chemical shift and are chemically equivalent.

Equivalence is determined by the replacement test, where each of the protons being examined is replaced by a substituent. If identical molecules are obtained, the protons are equivalent or homotopic.

In ethane, re...