Arrange benzene, n -hexane, and ethyne in decreasing order of acidic behaviour. Also, give a reason for this behaviour.

Question

Philoid · Accepted Answer

The acidic character of a species is defined as the ease with which it can lose its H^- atoms.

The hybridization state of carbon in the given compounds is as shown below:-

Now, as the s–character increases, the electronegativity of carbon increases and the electrons of C–H bond pair lies closer to the carbon atom. As a result, the partial positive charge of H^- atom increases and H⁺ ions are set free.

The s–character increases in the order:

sp³ < sp² < sp

Hence, the decreasing order of acidic behaviour is: -

Ethyne > Benzene > Hexane.

Arrange benzene, n-hexane, and ethyne in decreasing order of acidic behaviour. Also, give a reason for this behaviour.