Fundamentals of Organic ChemistryChemistryAlcohols Phenols and Ethers
Identify A and B in the following reactions: ( CH ₃ )₃ COH KMnO ₄ / OH ⁻ A ( CH ₃ )₃ COH KMnO ₄ / H ⁺ B
Options
- ABoth A and B are ( CH ₃ )₃ COH (no reaction)
- BA is ( CH ₃ )₃ COH (no reaction), while B is ( CH ₃ )₂ C = CH ₂ or ( CH ₃ )₂ CO
- CBoth A and B are ( CH ₃ )₂ CO + CH ₂ O
- DBoth A and B are ( CH ₃ )₂ C = CH ₂
Correct answer
B. A is ( CH ₃ )₃ COH (no reaction), while B is ( CH ₃ )₂ C = CH ₂ or ( CH ₃ )₂ CO
Step-by-step solution
Tertiary alcohols are resistant to oxidation in neutral or alkaline media. Therefore, when ( CH ₃ )₃ COH is treated with KMnO ₄ / OH ⁻ , no reaction occurs and the alcohol remains unreacted. Thus, A is ( CH ₃ )₃ COH . In acidic media, tertiary alcohols undergo dehydration to form alkenes. ( CH ₃ )₃ COH in the presence of KMnO ₄ / H ⁺ first dehydrates to give isobutylene, ( CH ₃ )₂ C = CH ₂ . This alkene can further undergo oxidative cleavage by KMnO ₄ to yield acetone, ( CH ₃ )₂ CO , and carbon dioxide. Thus, B is