The major product formed in the acid-catalyzed rearrangement reaction of 2-methyl-1,5-hexadiene is 3,3-dimethyl-1-butene.Here's the step-by-step process of the reaction:1. Protonation of the alkene: The acid catalyst donates a proton H+ to the alkene, forming a carbocation on the more substituted carbon Markovnikov's rule . In this case, the carbocation is formed at the tertiary carbon C3 adjacent to the methyl group.2. 1,2-hydride shift: A hydride H- from the adjacent carbon C2 shifts to the carbocation, forming a more stable secondary carbocation at C2.3. Deprotonation: A base usually the conjugate base of the acid catalyst abstracts a proton from the carbocation, forming the double bond and yielding the final product, 3,3-dimethyl-1-butene.