Question

When 2-heptyne was treated with aqueous sulfuric acid containing mercury(II) sulfate, two products, each having the molecular formula C7H14O, were obtained in approximately equal amounts. What are these two compounds?

Answer 1

Answer:

See explanation below

Explanation:

This is a reaction of alkyne hydration. We have aqueous sulfuric acid in HgSO4. This reagent is used to convert a alkyne into a ketone. The mechanism of reaction is taking place in 4 steps.

The first step is an electrophilic adition where the atom of Hydrogen that the acid provides, is added to the alkyne in the triple bond.

In this step, as Carbon 2 and Carbon 3, do not have any atom of hydrogen, the adition of this hydrogen could take place in either carbon 2 or carbon 3, that's why at the end you can have two products in equal amounts.

The second step is the adition of one molecule of water in the carbocation that appears in the previous step.

The third step, is an acid base equilibrium, where the hydrogen atom from the water that added to the heptene, is substracted (In this case by the conjugate base of the acid).

In this way, we will have an alcohol with a double bond. This is the enolic form of the molecule.

The final step is a tautomeric equilibrium, where the double bond of the C = C will pass to a double bond C = O forming a carbonile and therefore, a ketone.

If this was done in carbon 2 from step 1, you'll have the 2-heptanone. If it were on carbon 3, it will be the 3 - Heptanone.

Picture attached has the mechanism and products.