Write a short note on oxidation of alcohols. What are the different reactions involved, with suitable examples?

Question

Isaac Aronson · Accepted Answer

Oxidation reactions of alcohols

Some fundamental guidelines on this matter are as follows: i. Alcohol oxidation reactions' products depend on the substituents on the carbinol carbon; ii. Hydrogen (H) must be available on the carbinol carbon for each oxidation step to take place; iii. Primary alcohols can be oxidized to aldehydes or, ultimately, to carboxylic acids. In an aqueous environment, the main product is typically carboxylic acid. When dichloro-methane is used, PCC or PDC enable the oxidation to be stopped at the intermediate aldehyde. Ketones can be produced by oxidizing secondary alcohols (no additional oxidation reaction is required). Alcohols that are tertiary cannot be oxidized. Permanganate, chromate salts, dichromate salts, and chromatic acid are frequently used reagents in these oxidation reactions.

Ava Andrews · Answer

undefined The oxidation of alcohols involves the conversion of an alcohol molecule into a carbonyl compound, such as an aldehyde or ketone, through the loss of hydrogen atoms. There are several different reactions involved in the oxidation of alcohols, including:

1. Oxidation of primary alcohols to aldehydes: Primary alcohols can be oxidized to form aldehydes using mild oxidizing agents, such as pyridinium chlorochromate (PCC) or the Collins reagent (CrO3/pyridine). For example, ethanol can be oxidized to acetaldehyde:
   CH3CH2OH → CH3CHO

2. Further oxidation of primary alcohols to carboxylic acids: Primary alcohols can undergo further oxidation to form carboxylic acids using stronger oxidizing agents, such as potassium permanganate (KMnO4) or chromium trioxide (CrO3). For example, ethanol can be further oxidized to acetic acid:
   CH3CH2OH → CH3COOH

3. Oxidation of secondary alcohols to ketones: Secondary alcohols can be oxidized to form ketones using mild oxidizing agents, such as PCC or the Swern oxidation reagent (dimethyl sulfoxide (DMSO) and oxalyl chloride (COCl)2). For example, isopropanol can be oxidized to acetone:
   (CH3)2CHOH → (CH3)2CO

Overall, the oxidation of alcohols is an important reaction in organic chemistry and is used in various synthetic processes to produce carbonyl compounds.