Types of Amides

An amide group consists of a nitrogen atom, a carbon atom, and an oxygen atom. Other than this, we also need three other groups to define its structure and name completely. The general formula goes like- R1-(C=O)-N-(R2) (R3) here; all the R groups can be either hydrogen or any other hydrocarbon in general.

The –(C=O)N= part of amides is called the amide group (more correctly, carboxamide group).

Different types of amides, primary, secondary, and tertiary amines, are classified according to whether the amine subgroup has the form of NH2, NHR, NRR’, where R and R’ are non-hydrogen groups. The prefix “amide” is added to the stem of the parent acid’s name in standard nomenclature. Acetamide is the amide generated from acetic acid (CH3CONH2). 

IUPAC Names of the different types of amides

When an amide is derived from a primary or secondary amine, the nitrogen substituents are listed first in the name. Thus, the amide formed from dimethylamine and acetic acid is N, N-diethyl-acetamide (CH3CONEt2, where Et = CH3CH2). Usually, even this name is simplified to diethyl-acetamide. This simplification can be done when the two substituent groups are the same. Secondary or tertiary amides cyclic amides are called lactams.

The carboxylic acid’s name is changed from -ic acid (standard) or -oic acid (IUPAC) to -amide.

• Benzoic acid is converted to benzamide.
• The names of nitrogen-attached groups are appended to the front of the base name, with an N- prefix serving as a locator.

Lactams can also be subdivided depending on the number of carbon atoms in the ring. Some examples of this type are Beta-Lactam (when there are only two carbon atoms in the ring containing the amide), Gamma lactam (When the Lactam has three carbon atoms in the ring, and so on. 

Physical Character traits of Amides

Amides, unlike amines, do not have basic properties in solution because; 

• Electrons are not readily accessible for hydrogen bonding. 
• Movement of electrons by more electronegative atoms in the carbonyl group

Association of amides with different reactions

Different types of reactions require different types of amide; some reactions require amides to have two hydrogen atoms on the nitrogen to complete the reaction. Therefore it becomes imperative to give some examples of different types of amides. Some essential tertiary amides are dimethylethanolamine and dimethylacetamide. Some important secondary amides are N-ethyl acetamide, N-methyl acetamide, etc. The primary amides have an NH2 group, and therefore, their names are only dependent upon the primary chain of carbon and its substituents, like acetamide, propanamide, etc. 

• Ammonia reacts with carboxylic acids at high temperatures; a primary or secondary amine produces an amide. A primary amine generates a secondary amide. A secondary amine generates tertiary amide.
• To frame amides, acid halides interact with ammonia, 1° amine, and 2° amines.
• Each mole of acid chloride requires two moles of amine: one to form the amide and one to neutralise the HCl formed.
• To produce amides, acid anhydrides interact with ammonia and 1° and 2° amines. Two moles of ammonia or amine are required, one to form the amide and one to neutralise the carboxylic acid by-product.
• Esters form amides when reacting with ammonia and 1° and 2° amines. Esters are less reactive than acid halides or acid anhydrides.

Hydrolysis of Amides 

Hydrolysis of an amide requires much more vigorous conditions than hydrolysis of an ester,

• Hydrolysis in aqueous acid requires 1 mole of acid for each mole of amide. 
• The products are carboxylic acid and ammonium or amine salt.
• The hydrolysis of an amide in an aqueous base necessitates 1 mole of base for every mole of amide.
• A carboxylate salt and an amine are the end products.

The addition of nitrogen to an organic structure produces both amide and amine. However, the distinction between an amide and an amine rests in the link formed by nitrogen in both molecules. Nitrogen atoms are connected to the carbonyl group as an amide, but nitrogen atoms are bonded to the alkyl group as an amine.

In these terms, it seems like amide is a mixture of amine and carboxylic acid. One can get various amides by appropriately reacting a specific amine with a specific carboxylic acid with suitable reagents and under suitable reaction conditions. Amides generally have a higher boiling point when compared to similar amines.

Polyamides

Polyamides and amide polymers are created by combining diamines and dicarboxylic acids in a condensation polymerization reaction similar to that of polyester formation. Nylon is a type of synthetic polyamide. There are numerous types of Nylons. Nylon 66, a polymer of hexanedioic acid and 1,6-hexane diamine, was used as a monomer based on diamine and diacid monomers. The addition of aromatic rings to the polymer backbone increases the stiffness and toughness of polyamides. Polyamide Kevlar is one such polymer that is used to make bulletproof vests.

Conclusion

Amides are a significant functional group in organic chemistry and have a wide range of applications, particularly in living systems and medicines on which many people rely; an amide bond connects different amino acids to form the various proteins found in all living systems. The subtle differences between amides and regular amines allow for their functionality in proteins and other biomolecules required for sustaining life.