The relative order of basicity of conjugate bases is

The relative order of basicity of conjugate bases is
  1. $\mathrm{O} \mathrm{H}^{-} < \mathrm{O} \mathrm{R}^{-} < \mathrm{H} \mathrm{C} \equiv \mathrm{C}^{-}$
  2. $\mathrm{O} \mathrm{H}^{-} < \mathrm{H} \mathrm{C} \equiv \mathrm{C}^{-} < \mathrm{O} \mathrm{R}^{-}$
  3. $\mathrm{HC} \equiv \mathrm{C}^{-} < \mathrm{OH}^{-} < \mathrm{OR}^{-}$
  4. $\mathrm{HC} \equiv \mathrm{C}^{-} < \mathrm{OR}^{-} < \mathrm{OH}^{-}$

Solution

Hence, Weaker the acid, stronger is the conjugate base. \(\mathrm{H}_2 \mathrm{O} > \mathrm{R}-\mathrm{OH} > \mathrm{CH} \equiv \mathrm{CH}\) Water is more acidic than alcohols and alcohols are more acidic than alkynes. Alkynes are very weak acids hence their basicity will be highest. So the order of basicity of conjugate base is : \(\mathrm{OH}^{-} < \mathrm{OR}^{-} < \mathrm{HC} \equiv \mathrm{C}^{-}\) Option A is correct.

Asked in: JEE-TOPICTESTS-CHEMISTRY

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