Ch 15.6... - NMR Spectroscopy

Integration

area under the peak quantifies the # of protons giving rise to a signal

Multiplicity (splitting pattern)

number of peaks in a given signal

Multiplicity results from _____

magnetic affects that protons have on each other. indicated number of neighboring protons

What general can we follow to determine the multiplicity of a signal

n + 1

3 Key rules of Splitting

1. equivalent protons cannot split one another

2. to split each other, protons must be within 2 or 3 bond distance

3. n+1 rule only applies to protons that are all equivalent

Coupling Constant (J value )

degree to which neighboring proton will couple to its neighbor

J Value

the distance b/w peaks of a splitting patter (hertz)

• protons that are splitting each other will have the same constant

What splitting pattern would an isolated ethyl group give?

triplet (3H) and quartet (2H)

What splitting pattern would an isolated isopropyl group give?

doublet (6H) & septet (1H)

What splitting pattern would an tert-butyl group give?

Singlet of 9H integration

Complex splitting

occurs when proton has two kinds of neighboring proton

When does peak overlap occur in complex splitting

when the J_ac & J_ab are about the same value

What structure should you expect if the HDI =4+ ?

aromatic ring