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Imines contain a carbon-nitrogen double bond. Imines are made by reacting a primary amine with a carbonyl compound - an aldehyde or ketone. The reaction is reversible and forms water. If water is removed from the reaction as it forms, the reaction favors the products. If excess water is present, the reaction favors the amine and carbonyl starting materials. Imine formations often include an acid catalyst, but the reaction generally works with or without the catalyst. The solvent is typically an alcohol. The reaction occurs through five steps. Step one, the amine attacks the carbonyl. Step two, the alcohol solvent protonates the alkoxide in the tetrahedral intermediate. Step three, the deprotonated alcohol solvent, now an alkoxide, deprotonates the positively charged nitrogen. Step four, the nitrogen lone pair ejects the hydroxide group to form an iminium ion. Step five, the hydroxide deprotonates the iminium ion to form the imine. All steps are reversible.

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