Group 3 - Double and Triple Bonds

In this section, we will look at alkene, imine, enol ether and alkyne protons. It s convenient to consider the first three at this stage as they usually absorb in the 8-5 delta region and the alkyne is included here for convenience. 

Alkene chemical shifts can be estimated using Table 5.6. Use this table with the same circumspection as you would all other tables of this type. It s a useful guide, not gospel. 

Substitute the additive values in Table 5.6 into the following equation  

Approximate chemical shift of proton (ppm) = 5.25 + Zgem + Zcis + Ztrans 

These couplings are exemplified below with reference to styrene (Spectrum 5.10). 

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