When tertiary butyl alcohol t-butanol undergoes dehydration in the presence of concentrated sulfuric acid, it forms isobutylene also known as 2-methylpropene as the major product. The reaction proceeds via an E1 mechanism, where the alcohol is protonated by the sulfuric acid to form a tertiary carbocation, which then loses a proton to form the alkene. The overall reaction can be represented as:t-butanol 2-methyl-2-propanol isobutylene 2-methylpropene + H2O