Question

Select the correct order of basicity.

• A. $C{H}_{3}C{H}_2^{-}>C{H}_2=C{H}^{-}>HC\equiv C^{-}>O{H}^{-}$
• B. $C{H}_{3}C{H}_2^{-}>HC\equiv C^{-}>C{H}_2=C{H}^{-}>O{H}^{-}$
• C. $C{H}_{3}C{H}_2^{-}>O{H}^{-}>HC\equiv C^{-}>C{H}_2=C{H}^{-}$
• D. $O{H}^{-}>HC\equiv C^{-}>C{H}_2=C{H}^{-}>C{H}_{3}C{H}_2^{-}$

Answer 1

The correct option is A $C{H}_{3}C{H}_2^{-}>C{H}_2=C{H}^{-}>HC\equiv C^{-}>O{H}^{-}$

A carbanion is the conjugate base of a carbon acid.

$Basicstrengthofconjugatebase\propto$ $\frac{1}{acidicstrengthofconjugateacid}$

A hydrogen tends to be more acidic when attached to a more electronegative atom. Alkynes are more acidic than alkenes, which are in turn more acidic than alkanes, is that $sp$ carbon atoms are more electronegative than $s{p}^2$ carbon atoms, which are in turn more electronegative than $s{p}^3$ carbon atoms.

Acidic strength of conjugate acids $C{H}_{3}C{H}_3<C{H}_2=C{H}_2<HC\equiv CH<HOH$

The base strength would be:

$C{H}_{3}C{H}_2^{-}>C{H}_2=C{H}^{-}>HC\equiv C^{-}>O{H}^{-}$