Chemistry - GOC Question with Solution | TestHub

Conjugate bases : (a) isopropoxide, localised on O; (b) ClO⁻, charge on O bonded to electronegative chlorine, which stabilises it inductively (pKa of HOCl ≈ 7.5); (c) acetate, resonance-stabilised over two oxygens (pKa ≈ 4.8); (d) acetaldehyde enolate, resonance-stabilised but with much of the charge on carbon (pKa ≈ 17). So acetic acid $>$ HOCl $>$ isopropanol $>$ acetaldehyde α-H, i.e. c $>$ b $>$ a $>$ d. (The alcohol and the aldehyde α-H are very close, pKa ≈ 17; the enolate's charge resting partly on carbon makes it slightly weaker.)