Amide
Amides are organic compounds linking amino acids into proteins.
An amide, also known as an organic amide or a carboxamide, is a compound with the general formula R−C(=O)−NR′R″. The amide functional group plays an important role in the chemistry of life where, as peptide bonds, it links amino acids together to form proteins.
- field
- Organic chemistry
- known_for
- Peptide bonds in proteins; polyamides such as nylons and Kevlar; common solvents like dimethylformamide
- structure
- Planar due to delocalization of nitrogen lone pair into carbonyl group
- basicity
- Conjugate acid pKa around −0.5; much weaker bases than amines
Lore & Background
Amides can be viewed as a derivative of a carboxylic acid with the hydroxyl group replaced by an amino group, or an acyl group joined to an amino group. Common amides include formamide, acetamide, benzamide, and dimethylformamide. They are qualified as primary, secondary, or tertiary according to the number of acyl groups bound to the nitrogen atom. The lone pair of electrons on the nitrogen atom is delocalized into the carbonyl group, forming a partial double bond and a planar structure. This planar restriction prevents rotation about the N linkage, with important consequences for the mechanical properties of bulk materials and the configurational properties of macromolecules.
Reader's Guide
Amides are pervasive in nature and technology. Proteins and important plastics like nylons, aramids, Twaron, and Kevlar are polymers whose units are connected by amide groups (polyamides); these linkages are easily formed, confer structural rigidity, and resist hydrolysis. Amides include many other important biological compounds, as well as many drugs like paracetamol, penicillin and LSD. Low-molecular-weight amides, such as dimethylformamide, are common solvents. Compared to amines, amides are very weak bases, with conjugate acid pKa around −0.5.
Did You Know?
- The amide group is also called the carboxamide group.
- The C=O distance in amides is shorter than the C-N distance by almost 10%.
- For acetamide, the neutral resonance structure contributes 62% and the zwitterionic structure contributes 28%.
Frequently Asked Questions
Who is Amide?
An amide (also called a carboxamide or organic amide) is an organic compound whose core is a carbonyl carbon directly bonded to a nitrogen atom, expressed by the general formula R−C(=O)−NR′R″. It sits at the heart of organic chemistry as one of the most versatile nitrogen-containing functional groups.
What is Amide's role in the story of life?
As a peptide bond, the amide linkage is the molecular stitch that joins amino acids into the long chains we recognize as proteins. Without this specific bonding motif, the structural and enzymatic machinery of every living cell simply would not exist.
What makes Amide's structure unique?
The nitrogen lone pair is delocalized into the neighboring carbonyl group, forcing the entire amide unit into a rigid, planar geometry. This same resonance interaction also suppresses basicity, pushing the conjugate-acid pKa down to roughly −0.5 and making amides far weaker bases than comparable amines.
Why is Amide important beyond biology?
In materials science, repeating amide linkages form the backbone of polyamides such as nylon and Kevlar, lending those polymers exceptional tensile strength. Amides also double up as widely used laboratory solvents, with dimethylformamide being a particularly common example.
How does Amide compare to amines in terms of reactivity?
Although both contain nitrogen, an amide's lone pair is already engaged in resonance with the carbonyl, so it is far less available to accept a proton or act as a nucleophile. This is why amides behave as much weaker bases and are considerably less reactive at nitrogen than their amine counterparts.
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