How can you prove that a signal in a 1H NMR spectrum is from -OH or -NH2 group?

Question

How can you prove that a signal in a 1H NMR spectrum is from -OH or -NH2 group?

Answer 1

By performing the test again, with D2O present rather than H2O.

This cause the protons (these are called "labile protons") on OH and NH2 to be replaced by the heavier deuterium atoms which are not detected by the NMR.

If the peak in the H2O test disappears during the D2O test, you can confirm that the peak was indeed due to a labile proton.

Hope that helps...