(a) Reimer-Tiemann Reaction

• Step 1 (Definition): Treatment of phenol with chloroform ($CHCl_3$) in the presence of aqueous sodium hydroxide ($NaOH$) followed by acid hydrolysis leads to the introduction of a formyl group ($-CHO$) at the ortho position of the benzene ring.
• Step 2 (Reaction):
$$C_6H_5OH + CHCl_3 + 3NaOH \xrightarrow{H_3O^+} C_6H_4(OH)CHO + 3NaCl + 2H_2O$$
• Step 3 (Final Answer): The product formed is Salicylaldehyde (2-hydroxybenzaldehyde).

(b) Kolbe's Reaction

• Step 1 (Definition): Phenol reacts with sodium hydroxide to form sodium phenoxide, which then undergoes electrophilic substitution with carbon dioxide ($CO_2$) under pressure, followed by acidification.
• Step 2 (Reaction):
$$C_6H_5ONa + CO_2 \xrightarrow{400K, 4-7 atm} C_6H_4(OH)COONa \xrightarrow{H^+} C_6H_4(OH)COOH$$
• Step 3 (Final Answer): The product formed is Salicylic acid (2-hydroxybenzoic acid).

(c) Friedel-Crafts Acylation of Anisole

• Step 1 (Definition): Anisole reacts with an acyl chloride ($RCOCl$) in the presence of an anhydrous Lewis acid catalyst like anhydrous aluminium chloride ($AlCl_3$).
• Step 2 (Reaction):
$$C_6H_5OCH_3 + CH_3COCl \xrightarrow{Anhyd. AlCl_3} C_6H_4(OCH_3)(COCH_3) + HCl$$
• Step 3 (Final Answer): The major product formed is 4-methoxyacetophenone (p-methoxyacetophenone) due to the ortho/para directing nature of the methoxy group.