The quaternary ammonium hydroxide shown is heated strongly (Hofmann elimination). Which structure is the major alkene?

AStructure A
BStructure B
CStructure C
DStructure D

Answer: B

The salt is sec-butyltrimethylammonium hydroxide. The bulky, positively charged leaving group makes the E2 transition state carbanion-like, so the most acidic, least hindered beta-hydrogen (on the methyl group) is removed. This gives the Hofmann product but-1-ene rather than but-2-ene.

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