More Complex Examples of Splitting

Up to now you have studied examples of spin-spin splitting where the absorbing proton has nearby protons on one adjacent carbon only. What happens when the absorbing proton has nonequivalent protons on two adjacent carbons Two different outcomes are possible, depending on whether the adjacent nonequivalent protons are equivalent to or different from each other. 

The H NMR spectrum of 1-bromopropane (CH3CH2CH2Br) illustrates a different result. 

CH3CH2CH2Br has three different types of protons—Ha, Hb, and He—so it exhibits three NMR 

Hb is split into 12 peaks, labeled as a multiplet. Fewer peaks are seen because some peaks overlap. 

Three Hg protons split the Hb signal into 3 + 1=4 peaks. 

Problem 14.15 Although CI2CHCHCI2 and Br2CHCHCl2 each have only two hydrogens, these compounds have very different NMR spectra. For each compound, give the number of H NMR signals and indicate into how many peaks each signal is split. 

Problem 14.16 For each compound give the number of NMR signals, and then determine how many peaks are present for each NMR signal. 

Problem 14.17 Sketch the NMR spectrum of CH3CH2CI, giving the approximate location of each NMR signal. 

The Ha protons have only one adjacent nonequivalent proton (Hb), so they are split into two peaks, a doublet. 

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More complex examples of splitting Spin-spin splitting in alkenes... 

The examples of such type processes [66] are summarized in Scheme IV.33 (it can be seen from this scheme that examples of splitting C-C bonds between aromatic rings or between an aromatic ring and an alkyl group are investigated in more detail). However, usually reactions with metal complexes give different types of compounds [67] (Scheme IV.34) rather than simple dialkyl (diorganyl) derivatives, R-M-R. 

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