The correct answer is 271 Why is this Does the H in the OH n

The correct answer is 2,7,1. Why is this? Does the H in the OH not count? and what constiutes a neighboring hydrogen? I thought it was ones thats were directly adjacent but now im not sure.

Solution

The H of -OH and -NH2 does not couple with the adjacent C-H protons, due to the rapid exchange of these.

Due to this rapid exchange , their presence is not felt by the C-H protons and thus they appear as singlet only.

However , if we can reduce this exchange either by reducing the temperature or using a solvent like DMSO, the coupling with adjacent protons can be noticed and thesplitting is seen.