Synthesis of Alkenes by Dehydration of Alcohols - E1 Mechanism in Organic Chemistry

In the unimolecular elimination mechanism for the dehydration of an alcohol an alkene is the product. To understand how this happens in acidic media with sulfuric acid we consider acid-base reactions, ionization and proton transfers using the curved arrow formalism. In the first step, the hydroxyl group of the alcohol acts as a base to abstract a proton from sulfuric acid. The protonated oxygen can now ionize to leave as water resulting in the formation of a carbocation intermediate. Because we are starting with a secondary alcohol, a secondary carbocation results. There is no possibility for rearrangement as both beta carbons only have hydrogens and degenerate carbocation formation is not allowed. Once the carbocation is formed, the conjugate base of our starting acid or water will abstract a beta hydrogen to to the elimination and form the alkene.