This carbocation is a delocalized one and can be captured at either end of the allylic system bywater acting as a nucleophile.(c)Hydrogen bromide converts the alcohol to an allylic carbocation. Bromide ion captures thiscarbocation at either end of the delocalized allylic system.(d)The same delocalized carbocation is formed from 3-buten-2-ol as from 2-buten-1-ol.Since this carbocation is the same as the one formed in part (c), it gives the same mixture ofproducts when it reacts with bromide.(e)We are told that the major product is 1-bromo-2-butene, not 3-bromo-1-butene.The major product is the more stable one. It is a primary rather than a secondary halide andcontains a more substituted double bond. The reaction is therefore governed by thermody-namic (equilibrium) control.
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