Question

$(C{H}_3{)}_{3}CC{H}_{2}COOH$ is more acidic than $(C{H}_3{)}_{3}SiC{H}_{2}COOH$ because

• A. Size of Si is more than that of carbon
• B. Electronegativity of carbon is less than that of silicon
• C. Silicon is more electropositive than carbon due to which $(C{H}_3{)}_{3}SiC{H}_{2}CO{O}^{-}$ becomes less stable
• D. None of the above

Answer 1

The correct option is C Silicon is more electropositive than carbon due to which $(C{H}_3{)}_{3}SiC{H}_{2}CO{O}^{-}$ becomes less stable

The conjugate base of both acid are $C{H}_3-\stackrel{\stackrel{C{H}_3}{|}}{\underset{\underset{C{H}_3}{|}}{C}}-C{H}_2-\underset{\underset{O}{||}}{C}-O^{-}$

$C{H}_3-\stackrel{\stackrel{C{H}_3}{|}}{\underset{\underset{C{H}_3}{|}}{Si}}-C{H}_2-\underset{\underset{O}{||}}{C}-O^{-}$
Silicon is more electropositive than carbon due to which conjugate base $\left(\right(C{H}_3{)}_{3}SiC{H}_{2}CO{O}^{-})$ becomes less stable and hence less acidic.