Question

Dehydration of alcohol is an example of which type of reaction?

• A. Substitution
• B. Elimination
• C. Addition
• D. Rearrangement

Answer 1

Answer: (B)

Dehydration of alcohol involves the loss of two atoms or groups from the adjacent carbon atoms, hence it is an example of $\beta$-elimination reaction.
$\underset{\text{ ethanol}}{\stackrel{\beta }{C}{H}_3\stackrel{\alpha }{C}{H}_{2}OH}\stackrel{+H^{+}}{⟶}\stackrel{\beta }{C}{H}_3\stackrel{\alpha }{C}{H}_2\stackrel{+}{O}{H}_2\underset{-H_{2}O}{\to }$
$\stackrel{\beta }{C}{H}_3\stackrel{\alpha }{C}{H}_2^{+}\underset{-H^{+}}{\to }\underset{\text{ethanol}}{\stackrel{\beta }{C}{H}_2}=\stackrel{\alpha }{C}{H}_2$