H NMR Intensity of Signals

The relative intensity of H NMR signals also provides information about a compound s stracture. 

Integrals can be manually measured, but modem NMR spectrometers automatically calculate and plot the value of each integral in arbitraiy units. If the heights of two integrals are 20 units and 60 units, the ratio of absorbing protons is 20 60, or 1 3, or 2 6, or 3 9, and so forth. This tells the ratio, not the absolute number of protons. Integration ratios are approximate, and often values must be rounded to the nearest whole number. 

Problem 14.12 Which compounds give a NMR spectrum with two signals in a ratio of 2 3  

Knowing the molecular formula of a compound and integration values from its H NMR spectrum gives the actual number of protons responsible for a particular signal. 

Determine the Number of Protons Giving Rise to an NMR Signal 

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