Which type of alcohol is most likely to undergo dehydration reactions readily?

Tertiary alcohols are most likely to undergo dehydration reactions readily due to their molecular structure and the stability of the carbocation intermediates formed during the reaction.

In a dehydration reaction, an alcohol loses a water molecule, typically in the presence of an acid, to form an alkene. The reaction mechanism often involves the formation of a carbocation as an intermediate. Tertiary alcohols, which have three alkyl groups attached to the carbon bearing the -OH group, can stabilize this carbocation effectively through hyperconjugation and inductive effects. This increased stability makes the carbocation more favorable and increases the likelihood of the dehydration proceeding to completion.

In contrast, primary alcohols form less stable primary carbocations, which are much less favorable to form and therefore less likely to undergo dehydration. Secondary alcohols can form secondary carbocations, which are more stable than primary but less stable than tertiary, making them also less favorable for dehydration compared to tertiary alcohols. Quaternary alcohols do not undergo dehydration since they lack a hydrogen atom on the carbon with the -OH group; instead, they are fully substituted with alkyl groups.

Thus, the structural stability of the tertiary carbocation makes tertiary alcohols the most reactive toward dehydration reactions.