The alcohol shown is dehydrated by warming with dilute sulfuric acid. Which structure is the major alkene?

AStructure A
BStructure B
CStructure C
DStructure D

Answer: B

The alcohol is 2-methylbutan-2-ol, which reacts by E1 through a tertiary cation. Loss of a hydrogen from the CH2 group gives the trisubstituted 2-methylbut-2-ene (Saytzeff), more stable than the disubstituted 2-methylbut-1-ene. 3-Methylbut-1-ene would need a rearrangement.

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