Amides

Amide is an organic compound. It is also known as an organic amide or carboxamide. It contains a carbonyl functional group that is bonded with a nitrogen atom. The simplest amide is a derivative of ammonia NH₃, here one hydrogen atom is replaced by an acyl group.

In this article, we will define Amide, its types, structures, along with its properties.

Amide Functional Group
Nomenclature	Amides are named by replacing the -oic acid or -ic acid ending of the parent carboxylic acid with -amide. For example, ethanoic acid becomes ethanamide
Nature	Neutral or very weak acids
Appearance	White crystalline solid
Odor	Ethanamide, a simple amide, is said to smell like mice.
Density	Generally, they are denser than water.
Melting Point	Amides have high melting points. Melting point of butyramide is 115°C Melting point of benzamide is 132°C
Boiling Point	Amides have high boiling points due to the presence of strong hydrogen bonds. Boiling point of butyramide is 216°C Boiling point of benzamide is 290°C
Solubility	Soluble in Water

What is Amide?

Amide, also known as an organic amide or carboxamide, is a compound with the general formula R−C(=O)−NR′R″. Here R, R’, and R″ represent a hydrogen atom or an organic group.

Amides are derived from carboxylic acids, which contain the -COOH group. In an amide, the -OH part of that group is replaced by an -NH₂ group. Amides are essential in organic chemistry. They have various subclasses, such as carboxamides and phosphoramides.

Amide Definition

Amide is a compound that contains a carbonyl group linked to a nitrogen atom. It can also refer to any compound containing the amide functional group.

Amide Functional Group

Amide functional group is a compound with a carbonyl group attached to an amine group which are derived from the distinct functional group like carboxylic acid. It is represented as

R−C O N R₂

Where the R group represents a hydrocarbon or hydrogen substituent.

Read More, Functional Group

Amides Examples

Some examples of amides include:

• Acetamide (H₃C−C(=O)−NH₂)
• Benzamide (C₆H₅−C(=O)−NH₂)
• Paracetamol

Amide Formula

The formula for an amide is illustrated as:

RCONH₂

Where R represents an organic group connected to the carbonyl group.

This formula refers explicitly to primary amides. The nitrogen atom is bonded to two hydrogen atoms and no other R group.

Amide Structure

Amide group is a functional group that consists of a carbonyl group (C=O) linked to a nitrogen atom (N). The lone pair of electrons on the nitrogen atom is delocalized into the carbonyl group. This forms a partial double bond between nitrogen and carbon.

The O, C, and N atoms have molecular orbitals. They are occupied by delocalized electrons, creating a conjugated system. Consequently, the three nitrogen bonds in amides are planar, unlike the pyramidal shape of amines. Amides can participate in hydrogen bonding with water and other protic solvents. They can act as both hydrogen bond acceptors and donors.

Classifications of Amides

Amides can be classified into three types. This is based on the position of the nitrogen atom linked to the carbon atom. The three types of amides are:

• Primary Amide
• Secondary Amide
• Tertiary Amide

Primary Amides

In Primary Amides, the nitrogen atom is attached to a single carbon atom. The general formula for a primary amide is RCONH₂, where R represents an organic group or a hydrogen atom.

Primary amides are named by changing the name of the acid by removing “-oic acid” or “-ic acid” and after that adding “-amide”. For Example: Methanamide, Ethanamide, Propanamide, and Acetoamide.

Secondary Amides

In Secondary Amides(or 2° amides), the nitrogen atom is attached to two carbon atoms. The general formula for a secondary amide is RCONHR’, where R and R’ represent organic groups or a hydrogen atom.

Secondary amides are named using an uppercase N to designate that the alkyl group is on the nitrogen atom. Alkyl groups attached to the nitrogen are called substituents.

Tertiary Amides

In Tertiary Amides(or 3° amides), the nitrogen atom is attached to three carbon atoms. The general formula for a tertiary amide is RCONR’R″, where R ,R’ and R” represent organic groups or hydrogen atoms.

Tertiary amides are named similarly as secondary amides, but with two N’s.

Amide Bond

Amide bond is a specific type of covalent chemical bond. In organic chemistry, it is formed by the condensation reaction between a carboxylic acid and an amine.

When the amide group occurs in the main chain of a protein, it’s called a peptide bond. An isopeptide bond occurs in a side chain. Peptide bonds are essential in forming proteins. They link amino acids in a specific sequence.

Synthesis of Amide

There are several methods for the synthesis of amides. One common method is the direct reaction of a carboxylic acid and an amine using a coupling agent such as DCC. The reaction can be represented as follows:

RCO₂H + R’NH₂ + DCC → RCONHR’ + DCC (byproduct)

Another method involves the reaction of an acidic chloride with ammonia. It also involves the reaction with a primary amine or a secondary amine. The reaction can be represented as follows:

RCOCl + R’NH₂ → RCONHR’ + HCl

Amide Hydrolysis

Amide hydrolysis is the breakdown of an amide bond in a compound. It typically happens through a reaction with water. This process can occur under both acidic and basic conditions.

Amide hydrolysis is essential in various applications. It is used to hydrolyse peptides and proteins. The products of amide hydrolysis can be used to synthesize amines and carboxylic acids.

Reduction of Amide

Amides can be reduced to amines using various methods. One standard way is using a strong reducing agent like lithium aluminum hydride (LiAlH₄).

This reaction involves adding a hydride to the amide carbonyl. Then, it eliminates and adds a hydride ion to give the amine.

RCONR’₂ + 4[H] → RCH₂NR’₂ + 2H₂O

Where R and R’ are alkyl or aryl groups

LiAlH₄ is a strong reducing agent. It reacts violently with water. So, the reaction is carried out in dry solvents such as anhydrous ether.

Amide Vs. Amine

The difference between Amides and Amines are as follows:

Features	Amides	Amines
Functional Group	Amides have a carbonyl group (C=O) bonded to an amine group (NH2)	Amines have a nitrogen atom bonded with one or more alkyl group.
Nomenclature	Amides are named using the carboxylic acid nomenclature.	Amines are named based on the number of carbon atoms bonded to the nitrogen atom.
Basicity	Amides are weak bases due to the carbonyl group.	Amines are basic because the nitrogen atom has a lone pair of electrons.
Reactions	Amides can undergo hydrolysis with an aqueous acid or base. This breaks the amide bond to produce a carboxylic acid and either ammonia or an amine.	Amines can undergo various reactions. These include nucleophilic substitution, electrophilic substitution, and redox reactions.
Boiling Point	Amides have relatively higher boiling point.	Amines have relatively lower boiling point.

Applications of Amides

Some applications of amides include:

• Biological Molecules: Amide bonds are prevalent in biological molecules such as peptides, proteins, DNA, and RNA. Amide bonds’ unique stability and three-dimensional structures are responsible for their functions in these biomolecules.
• Pharmaceuticals: Several drugs consists of amides, including paracetamol. Amides are also used in the pharmaceutical industry for various applications.
• Polymer Industry: Nylon, a well-known synthetic polymer, is a polyamide. Amides are used to produce various synthetic fibers and plastics, including nylon.
• Solvents: Dimethylformamide (DMF), a common amide, is widely used as a solvent in organic synthesis and industrial processes.

Read More,

• Carboxylic acid
• Alkyl group
• Nomenclature of Organic Compounds

Amides – Solved Examples

Example 1: Which compound has the higher boiling point—pentanamide (CH₃CH₂CH₂CH₂CONH₂) or propyl acetate (CH₃COOCH₂CH₂CH₃)? Explain.

Solution:

Pentanamide because the nitrogen-to-hydrogen (N–H) and the carbon-to-oxygen double (C=O) bonds can engage in hydrogen bonding; propyl acetate cannot engage in hydrogen bonding.

Example 2: What are the products of the hydrolysis of an amide?

Solution:

A carboxylic acid and ammonia or an amine.

Amides – Frequently Asked Questions

What is Amide Formula?

The general formula for amides is RCONR₂, where R represents an organic group. For example, in acetamide (CH₃CONH₂), the formula highlights the presence of the amide functional group.

What are Characteristics of Amides?

Amides exhibit a carbonyl group (C=O) bonded to a nitrogen atom. They have a distinctively polar nature, allowing for hydrogen bonding. Amides are often found in proteins and play a vital role in biological molecules.

What are the Types of Amides?

Amides can be classified into primary (RCONH₂), secondary (RCONHR’), and tertiary (RCONR’₂) based on the number of organic groups attached to the nitrogen atom.

Is NH₃ called Amide?

No, NH₃ is not called an amide. NH₃ is ammonia, which is an amine. Amides have a carbonyl group (C=O) bonded to a nitrogen atom, unlike amines.

What is 3^o Amide?

“3^o Amide” refers to a Tertiary Amide. A 3^o amide molecule consists of the nitrogen atom which is bonded to three organic groups.

Is Amide Acidic or Basic?

Amides can act as both acidic and basic. However they tend to be very weak acids and therefore considered as neutral in general.

Is Amide Saturated or Unsaturated?

Amides are considered saturated. They do not have double or triple bonds between carbon and nitrogen atoms. The presence of a carbonyl group and single bonds defines their saturated nature.

Explain Amide Solubility in Water?

Amides are typically soluble in water. The presence of the polar carbonyl group allows for hydrogen bonding with water molecules, facilitating their dissolution.

What is the pKa of Amide?

The pKa of amides is usually around 16-18. It indicates that amides are relatively weak acids, and their protons are not readily dissociated under normal conditions.

Is an Amide an Amine?

While both contain nitrogen, an amide and an amine are distinct. Amides have a carbonyl group (C=O) bonded to nitrogen, while amines have nitrogen bonded to hydrogen atoms.

Are Amides Nucleophiles?

Amides can act as nucleophiles under certain conditions, participating in reactions where they donate a pair of electrons. However, they are generally less reactive than amines due to the presence of the carbonyl group.