1. Integration and Splitting

2. Integration • Area under signal is proportional to the number of protons in the set • RELATIVE AREA is calculated by computer

3. Integration • Trace of spectrum is cut into sections above each signal to give integration values Which proton set is this?

4. Integration • You need to “set” the values • Here is a more realistic outcome This is the NMR for a C5H10O compound. What are the integration values? 434.2 72.3 143.5 72.1

5. Product Distribution by Integration • In a mixture, areas are also proportional to number of protons • But they can by fractions A D E 43% 57% B B F F C C G G F B A E D

6. Splitting

7. Splitting • Shielding is also affected by magnetic fields of nearby nuclei

8. N + 1 Rule • The signal for protons b is a quartet • Signal b is “coupled” to the three protons labeled “a” • Four possible affects on signal b • Summarized by this simplification: n+1, where n = number of adjacent, nonequivalent protons

9. Splitting

10. Exchangeable protons • If protons exchange, they are not coupled • If protons are not coupled, they will no show splitting in signal • Typical for alcohols and acids

11. Label splitting for each proton set

12. N+1 is a Simplification • We learn it first because it applies to many molecules • Assumes that all adjacent protons couple to an identical, measureable degree • One exception: Aldehyde • We will learn a more robust treatment after we master first principles Very small coupling between these protons, even though they are adjacent