Amides Slides

Orgo 2 3rd Partial

Characteristics of Amides

They are very abundant organic compounds in Nature
that have the formula as a functional group
R – CO – NH2, are considered derivatives of the acids
carboxylic acids because the –OH has been replaced by a
amino group (NH2).

Boiling points (lowest → highest)

Alkanes < Alkenes < Esters < Amines < Alcohols < Carboxylic acids < Amides

Amides have the strongest hydrogen bonding (N–H and C=O) and extensive resonance stabilization of the carbonyl makes them cluster strongly.

Melting points (lowest → highest)

Alkanes < Alkenes < Esters < Amines < Alcohols < Carboxylic acids < Amides

Amides commonly have strong intermolecular H-bonding networks in the solid state → very high melting points.

Dimers

A dimer is usually not a new chemical compound, just a pair held together by intermolecular forces (often hydrogen bonds): Ex:

Two acids hydrogen-bond to each other:

• the carbonyl oxygen of one bonds to the OH of the other

• and vice versa

This “pairing” greatly increases boiling point.

properties of Amides 1

• Low-molar-mass amides are water- and alcohol-soluble
• Solubility decreases as molar mass increases
• The amide group is polar
• Except formamide (liquid), most amides are colorless crystalline solids
• Amides have high melting and boiling points

Properties of Amides 2

• Resonance restricts rotation of the C–N bond
• This restricted rotation is important for protein structure
• Tertiary amides lack N–H bonds and cannot form hydrogen bonds
• Amides behave as weak bases (practically Neutral)

Amide Synthesis: CH3-COOH + NH4OH →

Ethanamide CH₃-CONH₂

Acid hydrolysis of Amides

Amides can be hydrolyzed in an acidic
medium and heat to form carboxylic acids.

Ethanamide + H₂SO₄ + H₂O + Heat →Ethanoic acid + NH₄⁺

Amide reaction with NaOH

Amides react with strong bases and heat to form salts

Ethanamide + NaOH + H₂O + Heat → Sodium Ethanoate + NH₃

Amide Reaction with Alcohols

Amides react with alcohols to form Esters

Ethamide + Ethanol → Ethyl Ethanoate + NH₃

Reduction of Amides

Propanamide + LIAlH₄ → propylamine

Hoffmann Transposition

Propanamide + NaOH + Br₂ + H₂O → ethyl amine + CO₂

Uses of Amides

• In the pharmaceutical industry for the
  production of anesthetics.

• Production of Nylon is done with amide.

• Allow the links of the amino acids in the
  proteins.

• Used as foaming agents

• Acrylamine are used in the production of
  paper, metal extraction, textile industry,
  cooling and synthesis of other amides