Example of nuclear - Overhauser - Effect

 

For DMF:

 

·     both methyl groups are not  equivalent : d = 2,79 and 2,94

·     Formyl group at d = 8,0

 

If irradiated at:

 

n   2.94 the intensity of the formyl protons increases by 18%

n   2.79 the intensity of the formyl protons decreases by 2%