The standard aqueous hydrolysis of 2-bromo-3-methylbutane under moderate heating predominantly yield — Haloalkanes and Haloarenes Chemistry Question
Question
The standard aqueous hydrolysis of 2-bromo-3-methylbutane under moderate heating predominantly yields 2-methyl-2-butanol as the major organic product. What highly specific mechanistic transformation robustly explains this seemingly anomalous skeletal result?
💡 Solution & Explanation
When 2-bromo-3-methylbutane [$CH_3-CH(CH_3)-CH(Br)-CH_3$] undergoes ionization in a polar solvent, the bromide leaving group departs to form a secondary ($2^\circ$) carbocation: [$CH_3-CH(CH_3)-C^+H-CH_3$]. Because this carbon is directly adjacent to a tertiary carbon possessing a hydrogen atom, a 1,2-hydride shift enthusiastically occurs. The small hydrogen atom migrates with its bonding electrons to the positive center, shifting the positive charge to the tertiary carbon to form a highly stable $3^\circ$ carbocation: [$CH_3-C^+(CH_3)-CH_2-CH_3$]. Water nucleophilically attacks this new center, ultimately yielding 2-methyl-2-butanol.