27 Amines, amino acids and polymers Flashcards
What are amines?
Amines are organic compounds derived from ammonia, NH3, where one or more hydrogen atoms in ammonia have been replaced by a carbon chain or ring.
What is an aliphatic amine?
In an aliphatic amine, the nitrogen atom is attached to at least one straight or branched carbon chain (alkyl group, R)
What is an aromatic amine?
In an aromatic amine, each nitrogen atom is attached to an aromatic ring (aryl group, Ar)
How are amines classified?
By the number of alkyl or aryl groups attached to the nitrogen atom.
How many alkyl/aryl groups are attached to the nitrogen atom in primary, secondary and tertiary?
Primary- 1
Secondary- 2
Tertiary- 3
Examples where amines are used?
- Serotonin: neurotransmitter, responsible for control of appetite, sleep, memory and depression
- Pseudoephedrine: Ingredient in decongestion medications e.g nose drops
How do we name amines? (PRIMARY ONLY)
- When NH2 group is on carbon-1, we add suffix -amine e.g ethyl amine
- If NH2 isn’t on carbon 1 we add prefix amino- and a number is added to indicate position. E.g 2-aminobutane.
How do we name amines? (SECONDARY&TERTIARY)
- When they contain the same alkyl group, the prefixes di- or tri- are used to indicate the number of alkyl groups attached to the nitrogen atom.
- When two or more different groups are attached to a nitrogen atom, the compound is named as a N-substituted derivative.
How do amines behave as bases?
Amines behave as bases became the lone pair of electrons on the nitrogen atom can accept a proton.
What do you get when propylamine reacts with HCl?
Propylammonium chloride
What do you get when ethylamine reacts with H2SO4?
Ethylammonium sulfate
How does ammonia act as a nucleophile in a substitution reaction?
Ammonia has a lone pair of electrons on the nitrogen atom which allows ammonia to act as a nucleophile in a substitution reaction.
How are primary amines formed?
1) Ammonia + haloalkane = ammonium salt
2) Ammonium salt+ alkali = primary amine + salt + water
What are the essential conditions needed for formation of primary amines?
- Ethanol is used as the solvent which prevents any substitution of the haloalkane by water to produce alcohols.
- Excess ammonia is used to reduce further substitution of the amine group to form secondary & tertiary amines.
Why is the reaction unsuitable for making a pure primary amine?
- The product still contains a lone pair of electrons on the nitrogen atom that can react further with a haloalkane to form a secondary amine.
How is the secondary amine formed?
1) Primary amine + haloalkane = Salt (di)
2) Salt + sodium hydroxide = secondary amine + salt + water
How is phenylamine made?
1) Nitrobenzene + Tin + HCl -> Ammonium salt (phenylammonium chloride)
2) Phenylammonium chloride + NaOH -> Phenylamine
What acts as a reducing agent in the preparation of aromatic amines?
Tin and hydrochloric acid
What is an amino acid?
An amino acid is an organic compound containing both amine and carboxylic acid functional groups
RCH(NH2)COOH
What does the reaction between an amino acid and hydrochloric acid produce?
A salt.
E.g ammonium salt
What does the reaction between an amino acid and aqueous alkali produce?
Amino acid + aqueous alkali -> Salt + Water
What is the reaction between an amino acid and alcohol called?
Esterification
What is the reaction between an amino acid and alcohol produce?
Ester + Water
What conditions are required for the esterification of amino acids?
Heating amino acid with alcohol in presence of concentrated sulfuric acid
What does the reaction between acyl chloride and ammonia produce?
Primary amide + Ammonium Chloride
What does the reaction between acyl chloride and primary amine produce?
Secondary amide and ammonium chloride
In which molecules is optical isomerism found?
Optical isomerism is found in molecules that contain a chiral centre.
What is the chiral centre?
The chiral centre is a carbon atom that is attached to four different atoms or group of atoms.
What are optical isomers also known as?
Enantiomers
With the exception of glycine, which type of amino acids contain a chiral centre?
a-amino acids
What is condensation polymerisation?
A reaction in which two small molecules react together to form a larger molecule with a small molecule such as water being eliminated.
In which two ways can polyesters be made?
1) From one monomer containing both a carboxylic acid and alcohol group
2) From two monomers- one containing two carboxylic acid groups and other containing two alcohol groups
In which two ways can polyamide be made?
1) From one monomer containing both a carboxylic acid (or acyl chloride) and an amine group
2) From two monomers, one containing two carboxylic acid groups (or acyl chlorides) and the other containing two amine groups.
