Q.68. - Organic Chemistry

Question

Question: Isophorone is formed from three molecules of acetone $[{\left(C{H}_3\right)}_2=\mathrm{CO}]$ in the presence of base. Draw a mechanism for this process.

Step-by-Step Solution

Answer

Answer

Mechanism of formation of Isophorone

Step 1: Isophorone

Isophorone is an $\mathit{\alpha }\mathbf{,}\mathit{\beta }\mathbf{ }\mathit{u}\mathit{n}\mathit{s}\mathit{a}\mathit{t}\mathit{u}\mathit{r}\mathit{a}\mathit{t}\mathit{e}\mathit{d}\mathbf{ }\mathit{k}\mathit{e}\mathit{t}\mathit{o}\mathit{n}\mathit{e}$. The chemical formula for the compound is ${\mathit{C}}_{\mathbf{9}}{\mathit{H}}_{\mathbf{14}}\mathit{O}$  .

It is an industrial chemical used as a solvent in many adhesives, paints, and inks. It is also an intermediate in many organic syntheses.

It is also a monomer for many heteropolymers.

Step 2: Synthesis of Isophorone

Isophorone is synthesized from acetone in the presence of a base.

The reaction is an aldol condensation. Industrially, the base used is potassium hydroxide.

Many intermediates are formed in the reaction like mesityl oxide, diacetone alcohol, and other aldol products.

The side product of the reaction is beta isophorone.

Step 3: Mechanism of isophorone synthesis

The reaction is initiated by a base that produces the enol of acetone which reacts with another acetone molecule to form an unsaturated ketone.

The aldol reaction is repeated with another molecule of acetone.

The product undergoes internal cyclization followed by hydrolysis to form isophorone.

Mechanism of isophorone synthesis