Explain the mechanism of the following reaction: 2CH3CH2OH + H+ → CH3CH2OCH2CH3 + H2O

The reaction shown is an acid-catalyzed dehydration of ethanol to diethyl ether. The mechanism proceeds as follows:

Step 1: Protonation of the alcohol

A proton from the acid catalyst (H+) adds to the oxygen atom of ethanol, making it a better leaving group.

CH3CH2OH + H+ ⇌ CH3CH2OH2+

Step 2: Formation of a carbocation

The protonated alcohol loses a water molecule, forming a carbocation.

CH3CH2OH2+ → CH3CH2+ + H2O

Step 3: Nucleophilic attack

A second ethanol molecule acts as a nucleophile, attacking the carbocation.

CH3CH2+ + CH3CH2OH → CH3CH2-O+HCH2CH3

Step 4: Deprotonation

A base (water or another ethanol molecule) removes a proton from the oxygen atom, forming the diethyl ether and regenerating the acid catalyst.

CH3CH2-O+HCH2CH3 + H2O → CH3CH2OCH2CH3 + H3O+

Overall, the reaction is:

2CH3CH2OH + H+ → CH3CH2OCH2CH3 + H3O+

The reaction is a condensation reaction, where two molecules combine to form a larger molecule with the loss of a small molecule (water in this case). The acid catalyst is crucial, as it activates the alcohol molecule for the nucleophilic attack by protonating the hydroxyl group.