Q.Discuss the aromatic nucleophilic substitution reaction of chlorobenzene.

Step 1. Chlorobenzene resists ordinary nucleophilic substitution for two combined reasons: its C-Cl bond has partial double-bond character (short and strong, from resonance with the ring), and the aromatic ring is itself electron-rich, repelling rather than attracting an incoming nucleophile.

Step 2. Even so, sufficiently forcing conditions (very high temperature and pressure) can still displace the chlorine. With NaOH at 623 K and 300 atm, chlorobenzene gives phenol + NaCl -- this specific industrial process is called Dow's process.

Step 3. With excess ammonia at 523 K and 50 atm, chlorobenzene gives aniline (C6H5NH2) + NH4Cl.

Step 4. With cuprous cyanide (CuCN) in pyridine at 523 K, chlorobenzene gives phenyl cyanide (benzonitrile, C6H5CN) + CuCl. …

State why haloarenes resist nucleophilic substitution (strong C-X bond + electron-rich ring), then give the three named high-temperatu …

• Presenting these reactions as though they proceed as easily as a haloalkane's nucleophilic substitution -- the whole point of the topic is that they need dramatically more forcing conditions (high T and P) precisely b …