Alcohol Dehydration Producing Positional Alkene Isomers Steps:

• Dehydration of alcohols occurs via E1 mechanism for secondary/tertiary, forming a carbocation that loses a β-hydrogen to yield alkenes.
• Structural isomers result if the carbocation has non-equivalent β-carbons, allowing different double-bond positions.
• Analyze each option's structure to identify possible alkenes.
• Select the alcohol yielding exactly two distinct alkene structural isomers.

Why C is correct:

• CH₃CH₂CH(OH)CH₃ (butan-2-ol) forms CH₃CH₂CH⁺CH₃ carbocation; β-deprotonation from C₂ gives but-2-ene (CH₃CH=CHCH₃), from C₄ gives but-1-ene (CH₂=CHCH₂CH₃), positional isomers per Zaitsev's rule.

Why the others are wrong:

• A: CH₃CH₂CH₂OH (propan-1-ol) yields only propene (CH₃CH=CH₂) via concerted E2 or rearranged carbocation.
• B: CH₃CH(OH)CH₃ (propan-2-ol) forms symmetric (CH₃)₂CH⁺ carbocation, yielding only propene from equivalent β-hydrogens.
• D: CH₃CH₂CH₂CH₂OH (butan-1-ol) primarily yields but-1-ene (CH₂=CHCH₂CH₃); but-2-ene is minor, not two comparable structural isomers.

Final answer: C