Question

What will be formed after oxidation of secondary alcohol with chromic anhydride (CrO3)?

• A. Aldehyde
• B. Ketone
• C. Carboxylic acid
• D. Ester

Hint:

Chromic anhydride is a strong oxidizing agent that selectively oxidizes secondary alcohols to ketones without affecting aldehydes or carboxylic acids.

Answer 1

The Correct Option is B

To address the problem, we must identify the product resulting from the oxidation of a secondary alcohol using chromic anhydride (CrO\(_3\)).

1. Defining Secondary Alcohols:
A secondary alcohol possesses the general configuration R\(_1\)R\(_2\)CHOH, where R\(_1\) and R\(_2\) represent alkyl groups. This structure indicates that the carbon atom bonded to the -OH group is also attached to two other carbon atoms.

2. Identifying the Oxidizing Agent:
Chromic anhydride (CrO\(_3\)) functions as a potent oxidizing agent. It is frequently employed under acidic conditions (e.g., in the presence of H\(_2\)SO\(_4\)) to generate chromic acid, a standard reagent for alcohol oxidation. Alternative formulations exist, such as its use in Jones oxidation (CrO\(_3\) dissolved in aqueous sulfuric acid and acetone).

3. Oxidation Mechanism for Secondary Alcohols:
Upon oxidation of a secondary alcohol by a strong oxidizing agent like CrO\(_3\), the -OH group undergoes conversion into a carbonyl group (C=O). Given that the carbon atom is linked to two other carbon atoms, the resultant product is classified as a ketone (R\(_1\)R\(_2\)C=O). For illustrative purposes, the oxidation of 2-propanol (CH\(_3\)CH(OH)CH\(_3\)) with CrO\(_3\) yields acetone (CH\(_3\)COCH\(_3\)), which is a ketone.

4. Consideration of Reaction Conditions:
The use of CrO\(_3\) in an acidic medium ensures the complete oxidation of the alcohol. Unlike primary alcohols, secondary alcohols do not undergo further oxidation to carboxylic acids because the carbonyl carbon lacks a hydrogen atom, which would be necessary for subsequent oxidation to a carboxyl group.

Conclusion:
The oxidation of a secondary alcohol by chromic anhydride (CrO\(_3\)) produces a ketone.