The Question is from neet-chemistry organic-chemistry-basics attacking-regents, and it was created by the author Mr. S M HUSSAIN

Question

Which of the following reagents would be MOST effective in selectively oxidizing a secondary alcohol to a ketone in the presence of a primary alcohol?

Mr. S M HUSSAIN · Accepted Answer

## CORE INFORMATION
✓ **Answer**: A
## CONCEPT FRAMEWORK
 **Primary Concept**: Selective Oxidation of Alcohols
 **Related Topics**: Organic Chemistry, Oxidation-Reduction Reactions, Functional Group Transformations
 **Prerequisites**: Understanding of oxidation states, functional groups (alcohols, ketones, aldehydes, carboxylic acids), and the reactivity of different oxidizing agents.
## SOLUTION PATHWAY
**Given Information**:
We need to selectively oxidize a secondary alcohol to a ketone without oxidizing a primary alcohol present in the same molecule.
**Method & Steps**:
1. Analyze the oxidizing agents:
  Reasoning: Different oxidizing agents have different reactivities and selectivities.  Some will oxidize primary alcohols to aldehydes and then further to carboxylic acids, while others might stop at the aldehyde stage.  Secondary alcohols are typically oxidized to ketones.
  Formula/Rule: None specific formula, but understanding the oxidation power of each reagent is crucial.
2. Evaluate each reagent's selectivity:
  Working:
  * Dess-Martin periodinane ($C_{13}H_{14}IO_6$) is a mild oxidizing agent that selectively oxidizes primary alcohols to aldehydes and secondary alcohols to ketones. It's particularly useful for selective oxidation in the presence of other functional groups.
  * Jones reagent ($CrO_3$ in aqueous sulfuric acid) is a strong oxidizing agent that oxidizes primary alcohols to carboxylic acids and secondary alcohols to ketones. It lacks the selectivity needed for this question.
  * Potassium permanganate ($KMnO_4$) is a strong oxidizing agent that can oxidize primary alcohols to carboxylic acids and secondary alcohols to ketones.  Similar to Jones reagent, it lacks selectivity.
  * Sodium borohydride ($NaBH_4$) is a reducing agent, not an oxidizing agent. It would reduce ketones and aldehydes to alcohols.
  Key Point: Mild oxidizing agents are key to selective oxidation.
3. Identify the most selective reagent:
  Result: Dess-Martin periodinane is the most effective reagent for selectively oxidizing a secondary alcohol to a ketone in the presence of a primary alcohol.
  Verification: The mild nature of Dess-Martin periodinane prevents over-oxidation of the primary alcohol.
## OPTION ANALYSIS
A ✓: Dess-Martin periodinane is a mild and selective oxidizing agent that effectively oxidizes secondary alcohols to ketones without affecting primary alcohols significantly.
B :x: Jones reagent is a strong oxidizing agent and will over-oxidize the primary alcohol to a carboxylic acid.
C :x: Potassium permanganate is also a strong oxidizing agent and will over-oxidize the primary alcohol.
D :x: Sodium borohydride is a reducing agent; it would reduce any ketones or aldehydes present.
## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing oxidizing and reducing agents:  Remember that oxidizing agents increase the oxidation state of a molecule, while reducing agents decrease it.
  2.Overlooking the selectivity of reagents:  Strong oxidizing agents are not suitable for selective oxidations.
 **Quick Tips**:
  1.Remember the relative oxidizing strengths of common reagents.  Dess-Martin periodinane is a mild and selective choice.
  2.When dealing with selective oxidation, consider the reactivity and steric hindrance of the alcohol groups.

Mr. S M HUSSAIN · Answer

The correct Option is "Dess-Martin periodinane"

Mr. S M HUSSAIN · Answer

Jones reagent (chromic acid)

Mr. S M HUSSAIN · Answer

Potassium permanganate

Mr. S M HUSSAIN · Answer

Sodium borohydride

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