Chemistry - Halogen Derivative Question with Solution | TestHub
The alcohol among following which show dehydration reaction faster than 2-methyl propan-2-ol
Answer:
Solution:
Question Explanation: The question asks which alcohol undergoes dehydration faster than 2-methylpropan-2-ol (tert-butyl alcohol).
Concept: Dehydration of alcohols under acidic conditions follows E1 mechanism , and the rate depends on 3° > 2° > 1° alcohols carbocation stability : Additional stabilization occurs due to resonance (conjugation or aromaticity) .
Solution:
2-methylpropan-2-ol forms a stable tertiary carbocation .
Only those alcohols that form an even more stabilized carbocation will dehydrate faster.
(ii) Benzyl alcohol derivative:
On dehydration, it forms a benzylic carbocation , which is resonance-stabilized .
This makes dehydration faster than tert-butyl alcohol.
(viii) Cyclohexadienyl alcohol:
Dehydration leads to aromatic product , making the reaction extremely fast.
All other alcohols form less stable carbocations, so their dehydration is slower. Final Answer: 2
