3-Methylbutan-2-ol is heated with conc. $\mathrm{H}{}_2\mathrm{SO}{}_4$. The major alkene is:

Protonation and loss of water give a secondary carbocation at C2, which undergoes a 1,2-hydride shift from C3 to give the tertiary cation $(\mathrm{CH}{}_3){}_2\mathrm{C}{}^{+}-\mathrm{CH}{}_2\mathrm{CH}{}_3$. Loss of a proton from the methylene carbon gives the most substituted alkene, 2-methylbut-2-ene (Saytzeff), as the major product.