Splitting The Vinyl Group

When a hydrogen atom has more than one type of neighboring hydrogen atom, it is split into multiple peaks. The vinyl group is an example. 

There is no doubt about the assignment of the doublet of doublets centered at 7.28 5 because the oxygen atom causes a substantial deshielding of this hydrogen atom. 

The methylene protons of C-1 and C-3 are equivalent and appear in the 3—4 5 region with a total intensity of 4H. The methylene protons of the C-2 atom appear at higher field with intensity 2H. The low-field resonance is a triplet because the protons at either C-1 or C-3 are coupled with the two protons at C-2. The high-field resonance is a pentet because the C-2 methylene protons are coupled to a total of four equivalent protons at C-1 and C-3. 

The coupling of two nuclei results from an interaction passed through the network of bonding elec-cerT nC TRUPTURE Hteraction is not like theflowofelectricity though a wire. Instead, a conformational effect 

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