Amines, amides, condensation polymers Flashcards
How do amines react with acids?
- Amines are bases and they neutralise acids to make salts.
e.g propylamine + HCl:
CH3CH2CH2NH2 + HCl –> CH3CH2CH2NH3+Cl-
How are (aliphatic) primary amines made?
- Reaction of a 1-haloalkane with NH3. NH3 acts as a nucleophile.
- This produces an alkylammonium halide salt.
- The salt is then reacted with NaOH to produce a primary amine, Sodium halide, and water.
Conditions: ethanol as a solvent (prevents further substitutions), excess ammonia (reduces further substitutions of the amine group to form 2 & 3 amines)
How are secondary amines formed?
- First an ammonium salt is made from the primary amine and 1-haloalkane.
- The ammonium salt is then added to NaOH to produce a secondary amine, Sodium halide, and H2O.
What is wrong with the reaction to form primary amines?
- The formation of primary amines is unsuitable for making a primary amine as the product still contains a lone pair on the N which can react further with a haloalkane to form a secondary amine.
How are tertiary amines made?
- Further reaction of the secondary amine.
How are aromatic amines made?
- Phenylamine is made by the reduction of nitrobenzene.
- Nitrobenzene is heated under reflux with tin and HCl to form the ammonium salt (phenylammonium chloride), which is then further reacted excess NaOH to produce the aromatic amine, phenyl amine.
How can the -COOH group in amino acids react?
- with aqueous acids (e.g KOH/NaOH) to form a salt and water.
- Esterification. Heat with an alcohol in the presence of H2SO4.
What is a zwitterion?
- When the -NH2 group in a carboxylic acids accepts a proton from the -COOH to from an ion with positively (NH3+) and negatively (COO-) charged ions. No overall charge.
What is the isoelectric point?
- The pH at which the zwitterion is formed, each amino acid has its own unique one.
- If an amino acid is added to a solution with a pH greater than its isoelectric point it will behave as a n acid and will lose a proton (COO- formed).
- If an amino acid is added to a solution with a pH lower than its isoelectric point it will behave as a base and will gain a proton (NH3+) formed.
What is an amide?
- Amides are the products of reactions of acyl chlorides with ammonia and amines.
- In proteins, the COOH and NH2 groups of AAs bond to form an amide group.
- Consist of a C=O and a nitrogen bonded to between 1 and 3 carbons.
What are the different types of amides?
Primary: one C bonded to the N.
Secondary: two Cs bonded to the N.
Tertiary: three Cs bonded to the N.
What small molecules can be released by condensation polymerisation?
Usually H2O or HCl.
How can polyesters be made?
- Polyesters can be made from one monomer containing both a COOH and an OH, or from two monomers - one containing 2 COOHs and one containing 2OHs.
What is terylene?
- Polyethene terephthalate (PET).
- Reaction between benzene-1,4-dicarboxylic acid and ethane-1,2-diol.
- A hydroxyl group from the diol reacts with a carboxylic acid group from the dicarboxylic acid, releasing water and forming an ester linkage.
What are polyamides?
- Condensation polymers formed when monomers are joined together by amide linkages in a long chain to form the polymer.
- They can be made from one monomer with both a COOH (or acyl chloride) and an amide, or from two monomers, one containing two carboxylic acid groups (or acyl chlorides) and the other containing two amide groups.
