Q9-4P - Organic Chemistry (Mcmurry)

Question

What products would you obtain by hydration of the following alkynes?

Step-by-Step Solution

Answer

Answer:

a.

b.

Step1: Hydration of alkynes

Alkyne undergoes hydration in the presence of mercury(II) sulfate. The reaction occurs with Markovnikov regiochemistry, so the OH group adds to the more highly substituted carbon and the H attaches to the less highly substituted one.

Enol is an intermediate in the reaction, which rearranges into a ketone by a process called keto-enol tautomerism. The individual keto and enol forms are said to be tautomers.

Step2: Hydration of   CH 3 CH 2 CH 2 C ≡ CCH 2 CH 2 CH 3

The reaction occurs with Markovnikov regiochemistry. Enol is an intermediate in the reaction, which rearranges into a ketone by a process called keto-enol tautomerism

The symmetrical alkyne leads to the formation of the single product as shown:

Step 3: Hydration of   CH 3 CH ( CH 3 ) CH 2 C ≡ CCH 2 CH 2 CH 3

The reaction occurs with Markovnikov regiochemistry. Enol is an intermediate in the reaction, which rearranges into a ketone by a process called keto-enol tautomerism

The unsymmetrical alkyne leads to the formation of the two products as shown: