Question

The compound which gives the most stable carbocation in elimination reaction is

• A. (CH$_3$)$_3$COH
• B. CH$_3$CH$_2$CH$_2$CH$_2$OH
• C. CH$_3$CH(CH$_3$)CH$_2$OH
• D. CH$_3$CH(OH)CH$_2$CH$_3$
• E. CH$_3$CH$_2$OH

Hint:

Chemistry Tip: In alcohol dehydration, tertiary alcohols react fastest because tertiary carbocations are most stable.

Answer 1

The Correct Option is A

Concept:
During dehydration/elimination of alcohols (especially in acidic medium), water may leave first and form a carbocation intermediate. More stable carbocation forms more easily. General carbocation stability: $$3^\circ>2^\circ>1^\circ>CH_3^+$$ Reason:

• +I effect of alkyl groups
• Hyperconjugation
• Electron donation stabilizes positive charge

Step 1: Analyse each alcohol.
(A) (CH$_3$)$_3$COH
tert-Butyl alcohol On loss of water: $$(CH_3)_3COH \rightarrow (CH_3)_3C^+$$ This gives a tertiary carbocation. \vspace{0.5em} (B) CH$_3$CH$_2$CH$_2$CH$_2$OH
1-butanol gives primary carbocation. \vspace{0.5em} (C) CH$_3$CH(CH$_3$)CH$_2$OH
Isobutyl alcohol gives primary carbocation initially. \vspace{0.5em} (D) CH$_3$CH(OH)CH$_2$CH$_3$
2-butanol gives secondary carbocation. \vspace{0.5em} (E) CH$_3$CH$_2$OH
Ethanol gives primary carbocation.
Step 2: Compare carbocation stability.
Among all formed cations: $$3^\circ>2^\circ>1^\circ$$ So tert-butyl cation is most stable.
Step 3: Final answer.
Thus compound giving most stable carbocation is: $$\boxed{(CH_3)_3COH}$$ Hence correct option is (A). :contentReference[oaicite:0]{index=0}