Question
Question: ...

The final product is Cyclohexane-1,2-dione.
Solution
The reaction proceeds in two main steps:
Step 1: Nitrosation of Cyclohexanone
-
Generation of Nitrous Acid: Sodium nitrite (NaNO2) reacts with hydrochloric acid (HCl) to generate nitrous acid (HNO2). NaNO2+HCl→HNO2+NaCl
-
Formation of Nitrosonium Ion: Nitrous acid is protonated and then loses water to form the nitrosonium ion (NO+), which is a strong electrophile. HNO2+H+⇌H2O+−N=O⇌H2O+NO+
-
Enolization of Ketone: Cyclohexanone, being a ketone with alpha-hydrogens, exists in equilibrium with its enol form.
-
Electrophilic Attack: The nucleophilic alpha-carbon of the enol form attacks the electrophilic nitrosonium ion (NO+), forming an alpha-nitroso ketone.
-
Tautomerization: The alpha-nitroso ketone is generally unstable and rapidly tautomerizes to the more stable alpha-oxime ketone (2-(hydroxyimino)cyclohexan-1-one).
Step 2: Hydrolysis of the Oxime
-
Acid-catalyzed Hydrolysis: The alpha-oxime ketone (2-(hydroxyimino)cyclohexan-1-one) is subjected to acidic hydrolysis (H3O+). Under these conditions, the oxime group (=NOH) is hydrolyzed to a carbonyl group (=O), similar to the hydrolysis of an imine. This reaction releases hydroxylamine (NH2OH).
The final product is cyclohexane-1,2-dione.