Dehydration of an primary alcohol gives?

Here's a breakdown:

* Dehydration: This refers to the removal of water (H₂O) from a molecule.

* Primary Alcohol: An alcohol where the hydroxyl group (OH) is attached to a carbon that is only bonded to one other carbon.

* Alkene: A hydrocarbon containing a carbon-carbon double bond.

The Process:

1. Protonation: The alcohol is protonated by an acid catalyst, making the hydroxyl group a better leaving group.

2. Loss of Water: The protonated alcohol loses a molecule of water, leaving behind a carbocation.

3. Elimination: A base removes a proton from a carbon adjacent to the carbocation, leading to the formation of a double bond and an alkene.

Example:

The dehydration of ethanol (CH₃CH₂OH) gives ethene (CH₂=CH₂):

CH₃CH₂OH → CH₂=CH₂ + H₂O

Important Note:

The dehydration of primary alcohols requires a strong acid catalyst and high temperatures to proceed efficiently. The reaction often produces a mixture of alkenes, especially if the starting alcohol is branched.