Chapter 12, Problem 12P

Interpretation Introduction

Interpretation:

The oxidizing or reducing agents that would be used to carry out each of the given transformation is to be determined.

Concept introduction:

Swern oxidation reaction converts primary and secondary alcohols into aldehydes and ketones respectfully. The catalyst is a mixture of DMSO (dimethyl sulfoxide), oxalyl chloride in an organic base like triethylamine.

Reduction of carbonyl compounds to hydrocarbons is achieved by treating carbonyl compounds with lithium aluminum hydride $\left({\text{LiAlH}}_{\text{4}}\right)$.

Sodium borohydride $\left({\text{NaBH}}_{\text{4}}\right)$ can be also used to reduce carbonyl groups to alcohols but it can reduce only aldehydes or ketones.

Chromic acid oxidation: Oxidation of primary alcohols to aldehydes and use of hydronium (aqueous medium) to further oxidize the aldehydes to carboxylic acids is achieved by using chromic acid and water. Secondary alcohols are oxidized into ketones and no further reaction is involved since there are no hydrogen atoms attached to oxygen to be removed.

Pyridinium Chlorochromate (PPC): PPC is formed from pyridine, hydrochloric acid, and chromium oxide. This allows for controlled oxidation since this reaction takes place in anhydrous conditions.

Potassium permanganate: It is a strong oxidation agent that converts the primary alcohols and aldehydes to their corresponding carboxylic acids. It converts secondary alcohols to ketones. This is not a controlled reaction since the reaction occurs in aqueous medium.

When oxidation takes place, the hydrogen atom attached to the oxygen atom is removed to form aldehydes from alcohols or form carboxylic acids from aldehydes. Compounds with no hydrogen atom attached to oxygen cannot be oxidized using Swern oxidation. Examples of such compounds are tertiary alcohols and ethers.