What type of intermediate is formed during the reaction of alcohol with HBr?

When an alcohol reacts with HBr, it undergoes a substitution reaction to form an alkyl bromide. In this process, the alcohol is protonated by the acid (HBr), which results in the formation of a more reactive species. This protonation enhances the leaving ability of the hydroxyl group, which then departs as water, creating a positively charged intermediate known as a carbocation.

Carbocations are intermediates that contain a positively charged carbon atom, formed when a leaving group exits and leaves behind a vacant p-orbital. These intermediates are critical in determining the reaction pathway, for instance, influencing the rearrangement of the structure or the stability of the formed compound. The stability of the carbocation can further influence the mechanisms and products formed after this intermediate state.

In contrast to the other types of intermediates mentioned, such as radicals, carbanions, and enolates, a carbocation specifically pertains to a positively charged carbon, matching the nature of the intermediate formed when alcohols react with strong acids like HBr. This distinct behavior aligns well with the underlying chemistry involved in alcohol conversion to haloalkanes.