The alcohol shown is heated with concentrated sulfuric acid. A primary cation is not formed as a stable intermediate; a methyl group migrates as water leaves. Which structure is the major alkene?

The alcohol is 2,2-dimethylpropan-1-ol (neopentyl alcohol), which cannot eliminate directly because C-2 has no hydrogen. Methyl migration with loss of water gives the tertiary 2-methylbut-2-yl cation. Loss of a proton from the CH2 group gives the trisubstituted Saytzeff alkene 2-methylbut-2-ene as the major product. The alcohol is a hydration product, not a dehydration product.