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Multiple Choice
Which of the following alcohols will undergo acid-catalyzed dehydration the fastest and which one the slowest?
A
1 and 2
B
3 and 2
C
2 and 3
D
3 and 4
Verified step by step guidance
1
Identify the type of alcohols: Primary, secondary, or tertiary. Tertiary alcohols generally dehydrate faster than secondary, which dehydrate faster than primary alcohols.
Examine the structures: Alcohol 1 is a secondary alcohol, Alcohol 2 is a secondary alcohol, Alcohol 3 is a tertiary alcohol, and Alcohol 4 is a primary alcohol.
Consider the stability of the carbocation formed during dehydration: Tertiary carbocations are more stable than secondary, which are more stable than primary.
Analyze the substituents: Electron-donating groups like methoxy (-OCH3) can stabilize carbocations through resonance, enhancing the rate of dehydration.
Determine the fastest and slowest: Alcohol 3, being tertiary and having a methoxy group, will dehydrate the fastest. Alcohol 4, being primary, will dehydrate the slowest.