Amides

• Amides are a type of functional group in organic chemistry, characterised by the presence of a carbonyl group (C=O) attached directly to a nitrogen atom (N).

• The general formula of an amide is R-CO-NH2, where ‘R’ represents an alkyl or aryl group.

• Amides are classified into primary, secondary, and tertiary types based on the number of carbon-containing groups bonded to the nitrogen atom. Primary amides have one carbon group, secondary amides have two, and tertiary amides have three.

• Amides are polar compounds due to the presence of the carbonyl group and the N-H bond, which both have significant electro-negativity differences. This imparts properties like solubility in polar solvents.

• The C=O and N-H bonds in amides can form hydrogen bonds, especially in primary and secondary amides, leading to high boiling points compared to similarly sized molecules.

• Amides are commonly found in nature: for instance, proteins are composed of amino acids, which are amides.

• Amides can be synthesised by reacting an acid chloride or an anhydride with ammonia or an amine. Carboxylic acids can also react with ammonia/amine in the presence of a coupling agent to form amides.

• The reactivity of amides includes hydrolysis under either acidic or basic conditions to form a carboxylic acid and an amine or ammonia.

• Nitriles, the cyano group (-CN), can be hydrolyzed to form amides and further to carboxylic acids.

• Amides can be involved in amidation reactions where an existing amide reacts with an acyl chloride to produce a different amide.

• Amide linkages are key in forming peptides, proteins and a number of plastic materials known as polyamides or nylons.

Please review these points while preparing for Organic Chemistry III, focusing on the structure, properties, and reactivity of amides.