Question

Identify the correct reagents that would bring about the following transformation.

• A. (i) H₂O/H⁺
  (ii) CrO₃
• B. (i) BH₃
  (ii) \(H_2O_2/O^\ominus H\)
  (iii) PCC
• C. (i) BH₃
  (ii) \(H_2O_2/O^\ominus H\)
  (iii) alk. KMnO₄
• D. (iv)\(H_3O^\oplus\)
  (i) H₂O/H⁺
  (ii) PCC

Answer 1

The Correct Option is B

Step 1: Determine the Transformation Type

The transformation likely involves oxidation or hydroboration-oxidation, contingent on the existing functional groups.

Step 2: Analyze Reagent Functions

• \( BH_3 \) followed by \( H_2O_2/OH^- \): This sequence executes hydroboration-oxidation, resulting in the conversion of an alkene to an anti-Markovnikov alcohol.
• PCC (Pyridinium Chlorochromate): Functions as a mild oxidizing agent, transforming primary alcohols into aldehydes and secondary alcohols into ketones.
• Chromic acid (\( CrO_3 \)) in acidic medium: A potent oxidizing agent that oxidizes alcohols to carboxylic acids.
• Acidic water (\( H_2O/H^+ \)): Utilized for the hydration of alkenes, producing Markovnikov alcohols.

Step 3: Select the Appropriate Reagent Combination

Given that the transformation entails hydration followed by oxidation, the correct reagent sequence is:

1. \( BH_3 \) (for hydroboration).
2. \( H_2O_2/OH^- \) (for oxidation to alcohol).
3. \( PCC \) (for mild oxidation to aldehyde).

Step 4: Final Determination

The correct designation is:

Option (2): (i) \( BH_3 \), (ii) \( H_2O_2/OH^- \), (iii) PCC.