Is phenol more acidic than acetylene?

1 Answer
Nov 23, 2017

Phenol is more acidic than acetylene ( ethyne ) due to its hydroxyl group.

Phenol can lose a hydrogen ion because the phenoxide ion formed is stabilised. The negative charge on the oxygen atom is delocalised around the Benzylic ring. The more stable the ion is, the more likely the phenoxide ion is to form. The -OH group becomes more polar and hydrogen atom is released as a proton (H+). Hence, phenol is considered an organic Brønsted acid.

Furthermore, as @anor277 said, the #"pK_a# of phenol is #9.99# whereas, the #pK_a# of acetylene is #25.0#, thus, making phenol the stronger acid.