Chapter 14, Problem 39P

Given the following information, predict the appearance of the ${}^{1}H$ NMR spectrum arising from the vinyl hydrogen atoms of p-chlorostyrene. Deshielding by the induced magnetic field of the ring is greatest at proton $c\left(\delta 6.7\right)$ and is least at proton $b\left(\delta 5.3\right)$. The chemical shift of a is about $\delta$ 5.7. The coupling constants have the following approximate magnitudes: ${\text{J}}_{ac}\cong 18Hz,{\text{ J}}_{bc}\cong 11Hz$, and ${\text{J}}_{ab}\cong 2Hz$. (These coupling constants are typical of those given by vinylic systems: coupling constants for trans hydrogen atoms are larger than those for cis hydrogen atoms, and coupling constants for geminal vinylic hydrogen atoms are very small.)