3,3-Dimethylbutan-2-ol, (CH3)3C-CH(OH)-CH3, is heated with conc. H2SO4. The major alkene is

JEE Advanced levelSingle correct optionDifficulty 3 of 3ap197

3,3-Dimethylbutan-2-ol, $(CH X_{3}) X_{3} C - CH (OH) - CH X_{3}$ , is heated with conc. $H X_{2} SO X_{4}$ . The major alkene is

Loss of water gives a secondary cation next to a quaternary carbon. A methyl shift gives the tertiary cation

(CH X_{3}) X_{2} C X^{+} - CH (CH X_{3}) X_{2}

, and loss of

H X^{+}

to the carbon bearing two methyls gives the tetrasubstituted alkene (Saytzeff), 2,3-dimethylbut-2-ene.