Question

Draw a mechanism for this reaction. 5-hydroxypentanoic acid forms 2-oxanone in the presence of acid. draw all missing reactants and/or products in the appropriate boxes by placing atoms on the canvas and connecting them with bonds. add charges where needed. electron flow arrows should start on an atom or a bond and should end on an atom, bond, or location where a new bond should be created.

Answer 1

Answer: -

The first step involves protonation of the carbonyl oxygen.

After protonation, the Alcohol oxygen now attacks the carbon of the carbonyl.

Thus a six membered ring is formed with 5 carbon atoms and 1 oxygen atom. The 1st position carbon atom has 2 OH groups.

One of these gets again protonated.

This leaves as water. With the loss of the H+, there results a carbonyl at 1 position.

Thus 5-hydroxypentanoic acid forms a lactone or 2-oxanone in presence of acid.