Chapter 14, Problem 14.79P

Cyclohex- $2$-enone has two protons on its carbon–carbon double bond (labeled ${\text{H}}_{\text{a}}$ and ${\text{H}}_{\text{b}}$) and two protons on the carbon adjacent to the double bond (labeled ${\text{H}}_{\text{c}}$). (a) If $J_{\text{ab}}=11\text{Hz}$ and $J_{\text{bc}}=4\text{Hz}$, sketch the splitting pattern observed for each proton on the $s{p}^2$ hybridized carbons. (b) Despite the fact that ${\text{H}}_{\text{a}}$ is located adjacent to an electron-withdrawing $\text{C}=\text{O}$, its absorption occurs upfield from the signal due to ${\text{H}}_{\text{b}}$ ( $\text{6}\text{.0}$ vs. $\text{7}\text{.0 ppm}$). Offer an explanation.

cyclohex- $2$-enone