Amides

Quick Notes

• Amides

• Primary amide: RCONH₂
• Secondary amide: RCONHR′

Full Notes

Amides are derivatives of carboxylic acids, formed by replacing the –OH of a COOH group with –NH₂ or –NHR.

Primary amide: RCONH₂
Secondary amide: RCONHR′

Examples

CH₃CONH₂ (ethanamide) – primary

CH₃CONHCH₃ (N-methylethanamide) – secondary

Note: the N-methyl part of the name tells us that the methyl group is bonded to the nitrogen in the amide, rather than part of the main carbon chain.

Preparation of Amides

They can be made using acyl chlorides (see acyl chlorides).

RCOCl + NH₃ → RCONH₂ + HCl
Forms a primary amide. HCl produced reacts with excess NH₃ to form NH₄Cl.

RCOCl + R′NH₂ → RCONHR′ + HCl

Acyl chlorides can also react with secondary amines to form tertiary amides:
RCOCl + R′₂NH → RCONR′₂ + HCl

Summary

• Amides are derivatives of carboxylic acids with –CONH₂ or –CONHR groups.
• Primary amides: one substituent on nitrogen; secondary amides: two substituents.
• They can be prepared from acyl chlorides and ammonia or amines.
• Acyl chlorides with ammonia give primary amides; with primary or secondary amines they give secondary or tertiary amides.