Answer to Question #230613 in Organic Chemistry for Kay

Question

Which of the alkyne addition reactions below involve(s) an enol intermediate?

(1) hydroboration/oxidation

(2) hydrogenation in the presence of a metal catalyst

(3) halogenation

(4) none of the above

Answer 1

The correct answer is (1): hydroboration/oxidation.

Hydroboration/oxidation of alkynes involve an enol intermediate.

An intermediate is a specie that occurs along the steps of a non-elementary reaction but does not appear among the products.

Hydroboration refers to the reaction of borane (BH3) with alkyne. The addition of borane to an alkyne passes through an enol intermediae and the same also goes for oxidation of an alkyne.