Secondary alcohols rearrangements during

Some primary and secondary alcohols also undergo rearrangements of their carbon skeleton during dehydration. 

Some primary and secondary alcohols also undergo rearrangements of their carbon skeletons during dehydration. Such a rearrangement occurs in the dehydration of 3,3-dimethyl-2-butanol ... 

Many secondary alcohols give at least some rearranged product, evidence for the formation of carbocation intermediates during their reaction. For example, treating 3-pentanol with HBr gives 3-bromopentane as the major product, along with some 2-bromopentane. 

Silylation of Alcohols, pyridiniump-toluenesulfonate can be used as the catalyst in the silylation of primary and secondary alcohols and phenols (eq 3). Even alcohols sensitive to acid-catalyzed rearrangements can be successfully silylated under these conditions. Continuous removal of the water generated during the reaction is necessary and is achieved via the use of a Soxhlet extractor filled with 4A molecular sieves. 

An oxidative rearrangement took place during the MCPBA epoxidation of the secondary allylic alcohol auraptenol, leading to the enal shown in equation (20). This reaction has been used in an approach to casegravol and in a synthesis of amottinin. The reason why the intermediate epoxy alcohol undergoes rearrangement in this case is not known beyond the possibility that the m-chlorobenzoic acid by-product could act as an acidic catalyst. 

Dehydration of aicohois (Sections 5.9-5.13) Dehydration requires an acid catalyst the order of reactivity of alcohols is tertiary > secondary > primary. Elimination is regioselective and proceeds in the direction that produces the most highly substituted double bond. When stereoisomeric alkenes are possible, the more stable one is formed in greater amounts. A car-bocation intermediate is involved, and sometimes rearrangements take place during elimination. 

---