IB CHEMISTRY

Structure 3.2.10

Proton NMR: The Basics

Analyzing the magnetic resonance of Hydrogen nuclei to determine the skeleton of the molecule.

1. Number of Signals

Each signal represents a unique Chemical Environment. Protons in equivalent positions (symmetry) show up as the same signal.

Ethanol (CH3CH2OHCH_3CH_2OH)

3 Signals: CH3CH_3, CH2CH_2, OHOH

Propane (CH3CH2CH3CH_3CH_2CH_3)

2 Signals: The two CH3CH_3 groups are symmetrical (equivalent).

2. Integration Traces

The area under the peak (integration) is proportional to the number of protons in that environment.

A ratio of 3:2 suggests an Ethyl Group (CH3āˆ’CH2āˆ’CH_3-CH_2-).