2-Bromo-2-methylbutane is warmed in ethanol with no strong base present. The major alkene formed is

A3-methylbut-1-ene
Bpent-2-ene
C2-methylbut-1-ene
D2-methylbut-2-ene

Answer: D

Under these conditions the reaction goes by E1 (with competing SN1). The tertiary cation loses a beta-proton to give mainly the more substituted alkene (Saytzeff rule), i.e. the trisubstituted 2-methylbut-2-ene.

Practice Organic Reaction Mechanisms IV: Elimination More on E1 mechanism and carbocation rearrangement

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