Question

Why are tertiary alcohols resistant to oxidation ?

Hint:

Primary alcohols contain two \(\alpha\)-hydrogens, secondary alcohols contain one \(\alpha\)-hydrogen, whereas tertiary alcohols contain no \(\alpha\)-hydrogen and therefore resist oxidation.

Answer 1

Concept: The oxidation of alcohols generally involves the removal of hydrogen atoms from two locations:

• The hydroxyl group (\(-OH\)).

• The carbon atom directly attached to the hydroxyl group (called the \(\alpha\)-carbon).
For oxidation to proceed normally, at least one hydrogen atom must be present on the \(\alpha\)-carbon.

Step 1: Examine the structure of a tertiary alcohol The general structure of a tertiary alcohol is: \[ R_3C-OH \] The carbon atom attached to the hydroxyl group is bonded to three alkyl groups. Therefore, it possesses no hydrogen atom.

Step 2: Requirement for oxidation During oxidation, removal of the \(\alpha\)-hydrogen is essential for the formation of a carbonyl compound. Since tertiary alcohols do not contain any \(\alpha\)-hydrogen atom, this process cannot occur.

Step 3: Consequence To oxidize a tertiary alcohol, carbon-carbon bond cleavage would be required. Breaking carbon-carbon bonds requires a large amount of energy and therefore does not occur under ordinary oxidation conditions. As a result, tertiary alcohols remain unaffected by common oxidizing agents.

Conclusion \[ \boxed{ \text{Tertiary alcohols are resistant to oxidation because the carbon atom} \\ \text{bearing the hydroxyl group does not contain any }\alpha\text{-hydrogen.} } \] Hence normal oxidation cannot take place without cleavage of carbon-carbon bonds.