1H NMR (proton NMR) detects hydrogen nuclei. It gives more information than 13C NMR because it shows how many hydrogens are in each environment and what is next to them.Hydrogen atoms in the same chemical environment are equivalent and give one signal. So:
• the number of peaks = the number of different hydrogen environments
• the chemical shift of each peak shows the type of environment (for example, next to O or C=O)
• the relative area of each peak gives the ratio of hydrogens in each environment (integration)
• in a high resolution spectrum, the splitting of each peak shows the number of H on neighbouring carbonsA low resolution spectrum shows one peak per environment; a high resolution spectrum shows these peaks split into groups of lines.Worked example: ethanol, CH3CH2OH, has three hydrogen environments (CH3, CH2 and OH), so it shows 3 peaks with areas in the ratio 3:2:1. The CH2 peak is at about 3.7 because it is bonded to the oxygen atom; the CH3 peak is at about 1.2.Methyl ethanoate, CH3COOCH3, has two CH3 groups in different environments (one next to C=O, one bonded to O), so it shows 2 peaks in a 1:1 ratio, at about 2.0 and 3.7.The position of an OH peak varies with concentration and solvent. Shaking the sample with D2O makes an OH (or NH) peak disappear, because the H is exchanged for D.
• the number of peaks = the number of different hydrogen environments
• the chemical shift of each peak shows the type of environment (for example, next to O or C=O)
• the relative area of each peak gives the ratio of hydrogens in each environment (integration)
• in a high resolution spectrum, the splitting of each peak shows the number of H on neighbouring carbonsA low resolution spectrum shows one peak per environment; a high resolution spectrum shows these peaks split into groups of lines.Worked example: ethanol, CH3CH2OH, has three hydrogen environments (CH3, CH2 and OH), so it shows 3 peaks with areas in the ratio 3:2:1. The CH2 peak is at about 3.7 because it is bonded to the oxygen atom; the CH3 peak is at about 1.2.Methyl ethanoate, CH3COOCH3, has two CH3 groups in different environments (one next to C=O, one bonded to O), so it shows 2 peaks in a 1:1 ratio, at about 2.0 and 3.7.The position of an OH peak varies with concentration and solvent. Shaking the sample with D2O makes an OH (or NH) peak disappear, because the H is exchanged for D.