Question

The correct order of increasing basicity of the given conjugate bases (R = $C{H}_3$) is:

• A. $RCO\overline{O}<HC\equiv \overline{C}<\overline{R}<\overline{N}{H}_2$
• B. $\overline{R}<HC\equiv \overline{C}<RCO\overline{O}<\overline{N}{H}_2$
• C. $RCO\overline{O}<N{H}_2<HC\equiv \overline{C}<\overline{R}$
• D. $RCO\overline{O}<HC\equiv \overline{C}<\overline{N}{H}_2<\overline{R}$

Answer 1

The correct option is D $RCO\overline{O}<HC\equiv \overline{C}<\overline{N}{H}_2<\overline{R}$

The order of acidity can be explained on the basis of the acids of the given conjugate base$.$ Stronger is the acid$,$ weaker is the conjugate base$.$ Since$,$ $RCOO$ is the stronger acid amongst all$,$ $RCO{O}^{-}$ is the weakest base$.$ Due to $sp$ hybridised carbon$,$ acetylene is also acidic and hence a weak base but stronger than $RCO{O}^{-}.$ As ${sp}^3$ carbon is less electronegetive than ${sp}^3$ nitrogen$,$ $R^{-}$ is more basic than $N{H}_2.$