Q.Explain Kolbe's reaction.

Step 1. Phenol is first converted to sodium phenoxide by treatment with NaOH -- the phenoxide ion is considerably more electron-rich, and so more reactive toward electrophiles, than neutral phenol.

Step 2. Sodium phenoxide is then reacted with carbon dioxide at 400 K and 4-7 bar pressure; CO2 acts as a (comparatively weak) electrophile, attacking the highly activated ortho position of the phenoxide ring, and the reaction proceeds through a six-membered cyclic transition state that favours ortho- over para-carboxylation.

Step 3. This gives sodium salicylate directly; subsequent acid hydrolysis (H+/H2O) protonates both the carboxylate and the phenoxide, releasing free salicylic acid (2-hydroxybenzoic acid). …

Write the two stages separately: forming the more nucleophilic phenoxide ion first, then its pressurised reaction with CO …

• Trying to carboxylate PHENOL directly with CO2 -- phenol itself is not nucleophilic enough; the phenoxide …