Imine

What is Imine?

An imine is a functional group or chemical compound containing a carbon–nitrogen double bond.

Imines are chemical molecules with a double bond between carbon and nitrogen (C=N). They are made by substituting the oxygen atom in aldehydes and ketones with the (N-R) group. Imines are compounds with a C=N double bond. Their general formula is R₂C=NR.

Table of Contents

• Imine Formation
• Imine Functional Group
• Imine Reduction
• Imine vs Enamine
• Frequently Asked Questions – FAQs

Imine Formation

The nitrogen counterparts of aldehydes and ketones are imines, which have a C=N bond instead of a C=O link. They’re made when an aldehyde or ketone reacts with an amine to dehydrate it. Aldimines and ketimines are terms used to describe imines generated from aldehydes and ketones, respectively. Enamines are enols’ nitrogen analogues.

Imines are produced in high yields from a mild three-component reaction involving aromatic aldehydes, alkyl bromides, and aqueous ammonia as the nitrogen source. A wide range of functional groups are compatible with the reaction conditions. Regioselectively, aldehydes and aqueous ammonia react with epoxides to produce imines with a vicinal hydroxyl group.

The formation of an imine is a two-step process from a chemical aspect. In the first stage step, 1 is the amine nitrogen attacks the carbonyl carbon in a nucleophilic addition reaction that is similar to hemiacetal and hemiketal synthesis. Based on the understanding of the acetal and ketal creation mechanisms, we could predict the next step to be an assault by a second amine, resulting in a molecule with a carbon bonded to two amine groups the nitrogen equivalent of a ketal or acetal. Instead, the nitrogen lone pair electrons ‘push’ the oxygen off of the carbon, generating a C=N double bond (an iminium) and a displaced water molecule.

Imine Functional Group

A functional group or chemical molecule having a carbon–nitrogen double bond is known as an imine. Hydrogen (H) or an organic group can be added to the nitrogen atom (R). If this group does not contain a hydrogen atom, the chemical is known as a Schiff base.

Imine Reduction

Reductive amination is used to decrease imines. For example, in the production of m-tolyl benzylamine, an imine can be converted to an amine by hydrogenation.

Other reducing agents are lithium aluminium hydride and sodium borohydride.

Imine vs Enamine

Imine and enamine are chemical molecules that include nitrogen. Enamines are organic compounds with an amine group adjacent to a C=C double bond. Imines are organic compounds with a C=N functional group, while enamines are organic compounds with an amine group adjacent to a C=C double bond. The main distinction between imine and enamine is that imine has a C=N bond while enamine has a C-N bond.

Imines resemble carbonyls and are generated when a primary amine (or ammonia) reacts with a carbonyl-containing acid (H⁺, H₃O⁺). In its most basic form, it resembles a carbonyl with a double bond to nitrogen rather than oxygen. We’ll notice that when the reaction is finished, we’ll be left with a structure similar to this (above in green). The R group that was bonded to the initial primary amine before it reacted is what the three-carbon chain is.

Enamines, on the other hand, are formed when carbonyls react with a secondary amine and have a double bond to carbon rather than nitrogen.