14.2 Acidity of Alkynes

  Hydrocarbons

$ - C \equiv CH$ bond has considerable ionic character due to resonance.

The electronegativity of a carbon atom depends on the number of bonds by which it is attached to its neighbouring carbon. The carbon with electronegativity of an $s{p^2}$ hybridised carobn atoms is greater than that of $s{p^3}$ hybridised carbon atom and the electronegativity of an sp hybridized carbon atom is further greater than that of $s{p^2}$ carbon atom. More the s – character a bond has more electronegative is the carbon atom. Thus the attraction for electrons by hybridized carbon will be

$$sp{\text{ }} > {\text{ }}s{p^2} > {\text{ }}s{p^3}$$

Hence greater the electronegativity of an atom, more readily it accommodates a negative charge.

$\therefore $ Stabilities of the following carbanions follows the order.

$$CH \equiv {C^ - } > {\text{ }}C{H_2} = {\text{ }}C{H^ - }_{} > C{H_3}C{H_2}^ - $$