Difference Between Amine and Amide

Main Difference – Amine vs Amide

Amines and amides are two types of compounds found in the field of organic chemistry. Although both types are composed of nitrogen atoms along with other atoms, there are distinct characteristics and properties present in amines and amides. The main difference between amine and amide is the presence of a carbonyl group in their structure; amines have no carbonyl groups attached to the nitrogen atom whereas amides have a carbonyl group attached to a nitrogen atom.

Key Areas Covered

1. What is an Amine
      – Definition, Structure, Properties, Classification
2. What is an Amide
      – Definition, Structure, Properties, Classification
3. What are the similarities between Amine and Amide
      – Common Properties
4. What is the difference between Amine and Amide
      – Comparison of Key Differences

Key Terms: Amine, Amide, Aliphatic Amide, Aliphatic Amine, Aromatic Amide, Aromatic Amine, Primary Amide, Primary Amine, Secodary Amide, Secodary Amine, Tertiary Amide, Tertiary Amine,

What is an Amine?

An amine is a derivative of ammonia. It is composed of one or more alkyl groups which replace the hydrogen atoms in ammonia (NH₃) molecule. Therefore, the alkyl group is directly bonded to the nitrogen atom. According to the number of alkyl groups that have been attached to the nitrogen atom, amines are categorized into three broad groups.

Classification of Amine

Primary Amines – One alkyl group is attached to the nitrogen atom.

Secondary Amines – Two alkyl groups are attached to the nitrogen atom.

Tertiary Amines – Three alkyl groups are attached to the nitrogen atom.

Figure 1: Primary amine (left), Secondary amine (right), Tertiary amine (bottom) Note that R1 and R2 groups can be the same or different in secondary and tertiary amines.

According to the type of alkyl group that has been attached, amine are further classified as,

Aliphatic Amines – No ring structures present

Aromatic Amines – Ring structures present

Aliphatic amines have linear or branched alkyl groups attached to the nitrogen atom directly. Aromatic amines have nitrogen atom directly connected to an aromatic ring structure.

Primary and secondary amines have H atoms bonded directly to the nitrogen atom. Therefore, primary and secondary amines are capable of having hydrogen bonds. Tertiary amines have no H atoms to make hydrogen bonds. But all amine types can have intermolecular hydrogen bonds with water (H₂O) due to the presence of a lone electron pair on the nitrogen atom. Therefore, amines with a low molecular weight can be dissolved in water.

As same as ammonia, amines also act as bases. The reasons for basicity includes the presence of a lone pair on the nitrogen atom, the presence of alkyl groups (alkyl groups enhance basicity of compounds by donating electrons to the nitrogen atom), etc.

What is an Amide?

Amides are organic compounds having a carbonyl group attached to the nitrogen atom directly. Amides can also be classified as aliphatic and aromatic amides. The aliphatic amides are classified into three groups as follows.

Classification of Amides

Primary Amide – the nitrogen atom is not bonded to any alkyl group

Secondary Amide – the nitrogen atom is bonded to a single alkyl group

Tertiary Amide – the nitrogen atom is bonded to two alkyl groups

Amides are derived from deprotonated ammonia. This deprotonated ammonia can be attached to an acyl group (R-C=O) and form an amide. Amides are also formed from carboxylic acids. There, the hydroxyl group (-OH) of carboxylic acid is replaced with deprotonated ammonia.

Figure 2: Primary (left), Secondary (right) and Tertiary (bottom) Amides

Similarities Between Amine and Amide

Both amines and amides are soluble in water due to the presence of a –NH group.

These –NH groups can make intermolecular hydrogen bonds with water molecules.

Amines and amides are classified into aliphatic and aromatic compounds based on the presence or absence of a ring structure.

Amines and amides are classified also as primary, secondary or tertiary compounds according to the number of alkyl groups attached to the nitrogen atom

Definition

Amine: Amine is an organic compound made out of one or more nitrogen atoms bonded with alkyl groups.

Amide: Amide is an organic compound made of deprotonated ammonium group with an acyl group.

Structure

Amine: Amines have no carbonyl groups in their structure.

Amide: Amides have carbonyl groups.

Atoms

Amine: Amines are composed of C, H and N atoms.

Amide: Amides are composed of C, H, N and O atoms.

Chemical Properties

Amine: Amines show basicity.

Amide: Amides show acidic characteristics.

Physical State

Amine: Most low molecular weight amines are gases at room temperature or are easily vaporized.

Amide: Most amides are solids at room temperature.

Boiling Points

Amine: Amines have relatively lower boiling points.

Amide: Amides have relatively high boiling points.

Conclusion

Both amines and amides are nitrogen (N) containing organic compounds. But they are different from each other according to their physical and chemical properties. The main difference between amine and amide depends on the presence or absence of carbonyl groups attached to their nitrogen atom.

References:

1. ” Physical Properties of Amides.” Chemistry LibreTexts. Libretexts, 08 Dec. 2016. Web. Available here. 12 June 2017.

Image Courtesy:

1. “Primary-amine-2D-general” By Kes47 (Public Domain) via Commons Wikimedia
2. “Secondary-amine-2D-general” By Kes47 (Public Domain) via Commons Wikimedia
3. “Amine-2D-general” By Kes47 (Public Domain) via Commons Wikimedia
4. “Amide-(primary)-skeletal”By Benjah-bmm27 (Public Domain) via Commons Wikimedia
5. “Sec. Amide Structural Formulae V.1” By Jü – Own work (Public Domain) via Commons Wikimedia
6. “Amide-(tertiary)-skeletal” By Benjah-bmm27 (Public Domain) via Commons Wikimedia