Carboxylic Acids: 5-Bullet Rapid Recall

Acidity: RCOO– is resonance-stabilized (bond order 1.5); pKa ladder: RCOOH (4–5) > ArOH (10) > H2O (15.7) > ROH (16–18) > RC≡CH (25); –I groups increase acidity, +I decrease; Cl3CCOOH (0.65) >> HCOOH (3.75) > CH3COOH (4.76).
Reduction trap: LiAlH4 reduces RCOOH → RCH2OH. NaBH4 gives NO reaction with RCOOH. (The single most tested NEET point in this chapter.)
HVZ: X2/Red P → alpha-halo acid. Requires alpha-H. HCOOH and ArCOOH cannot undergo HVZ.
Esterification vs Saponification: Fischer (RCOOH + R'OH/H2SO4) = reversible. Saponification (RCOOR' + NaOH) = irreversible → gives RCOONa (salt), not free acid.
Named Reactions: Kolbe electrolysis → R–R at anode; Soda lime → (n–1)-C alkane; Grignard + CO2 → RCOOH (n+1 C); SOCl2 → RCOCl + SO2↑ + HCl↑ (cleanest).