Lecture on Polyamines

Overview

• Condensation polymerization.
• Produces water as a byproduct.
• Combines a carboxylic acid with an amine, forming an amide group as the linkage.

Key Concepts

Amide Group Formation

• Structure: COOH + NH -> forms CO-NH + H₂O.
• Forms the linkage between monomers (amide bond).

Formation of Polyamides

Using Dicarboxylic Acid & Diamine

• Example 1: Combination of butane-1,4-diamine and ethanedioic acid (oxalic acid).
  • Carboxylic acid and amine react to form amide bonds.
  • Produces a repeating unit with specific structure involving carbons, amines, and double bonded oxygen (C=O).
• Note: Draw structures with appropriate bonds and indicate end groups to show repeating units.

Using Cyclohexane and Propanedioic Acid

• Example 2: 1,3-cyclohexane diamine and methylpropanedioic acid.
  • Cyclohexane structure with amine groups.
  • Dicarboxylic acid combined with diamine forming structured polymers.
• Ensure open-ended structures to denote repeating units.

Using Monomer with One Carboxylic Acid & One Amine Group

• Example: Amino acids (similar to polyesters formed from alcohol and carboxylic acid).
• Backbone involves chains of carbons with amine and carboxylic acid groups.

Examples

• 2-amino-4-pentanoic acid (adjusted to 4-amino for variety).
  • Structure with four carbons between NH and COOH groups.
  • Amino (NH₂) group as side chain.
• 4-amino benzoic acid: Benzene ring structure with COOH at position 1 and NH₂ at position 4.
  • Carboxylic acid and amine locations defined for specific bonding.

Drawing Tips

• Keep structures open-ended and repeat units marked.
• Include all hydrogen atoms for clarity.

Conclusion

• Practice drawing polymer structures and understanding their formation from different monomers.
• Review concepts for better grasp on polyamides and their chemical behavior.

Practice Questions:

1. Draw the structure of a polyamide formed from a given dicarboxylic acid and diamine.
2. Explain the formation process of an amide bond in polyamides.