Chapter 27 - Amines, Amino Acids and Polymers Flashcards
What are amines?
Organic compounds derived from ammonia, in which one or more hydrogen atoms in ammonia have been replaced by a carbon chain or ring
What is an aliphatic amine?
Where the nitrogen atom is attached to at least one straight or branched carbon chain (alkyl group, R)
What is an aromatic amine?
Where the nitrogen atom is attached to an aromatic ring
What is the difference between primary, secondary and tertiary amines?
Primary - N atom attached to 2 H atoms and one R group
Secondary - N atom attached to 1 H atom and two R groups
Tertiary - N atom attached to 3 R groups
What is the suffix and prefix for naming amines?
Suffix - amine
Prefix - amino
How do amines behave as bases?
The lone pair of electrons on the nitrogen atom can accept a proton
What happens when an amine accepts a proton?
A dative covalent bond is formed between the lone pair of electrons on the nitrogen atom and the proton
What happens when amines react with acids?
They neutralise them to form salts
How do you prepare aliphatic amines?
Nucleophilic substitution reaction between ammonia and a haloalkane to form an ammonium salt.
Aqueous alkali is then added to generate the amine from the salt.
What reagents/conditions are necessary for the preparation of aliphatic amines?
- ethanol used as solvent (prevents substitution of haloalkane by water to form alcohol)
- excess ammonia must be used to reduce further substitution of the amine group
How do you prepare aromatic amines?
Reduction of a nitro group using tin and concentrated hydrochloric acid and then NaOH
Nitrobenzene + 6[H] → phenylamine + 2H2O
What is an amino acid?
An organic compound containing both amine, NH2 and carboxylic acid, COOH functional groups
What is the general formula of an amino acid?
RCH(NH2)COOH
How does the amine group of an amino acid react with acids?
Reacts with acid to form salts
(ammonium salts)
How does the carboxylic acid group of an amino acid react with alkalis and alcohols?
Alkalis - forms salt and water
Alcohols - form ester and water when heated in presence of concentrated sulfuric acid
What are amides, what is their functional group?
Amides are the products of reactions of acyl chlorides with ammonia and amines
Functional group = Co-NH
What is optical isomerism?
Found in molecules with a chiral centre, creating two non superimposable mirror image structures known as optical isomers or enantiomers
What is a chiral centre?
A carbon atom that is attached to 4 different atoms/groups of atoms
How do you draw optical isomers?
Drawn to show 3D tetrahedral arrangement of 4 different groups around central chiral carbon atom. Use of dashed, black triangle and 2 straight lines.
What is condensation polymerisation?
The joining of monomers with the loss of a small molecule, usually water or hydrogen chloride
2 different functional groups are required
What is a polyester?
Monomers joined together by ester linkages in a long chain to form the polymer
What can polyesters be made from?
One monomer containing both a carboxylic acid and an alcohol
OR two monomers - one with 2 carboxylic acid groups and the other with 2 alcohol groups
What are polyamides?
Condensation polymers formed when monomers are joined together by amide linkages in a long chain to form the polymer
What can polyamides be made from?
One monomer containing both a carboxylic acid (or acyl chloride) group and an amine group
OR two monomers, one containing 2 carboxylic acid groups (or acyl chlorides) and the other containing 2 amine groups
What are the two ways that condensation polymers can be hydrolysed?
Hot aqueous alkali or hot aqueous acid
What does the alkaline hydrolysis (NaOH/H2O) of a polyester produce?
Sodium salt and an alcohol (diol)
What does the acid hydrolysis (H+/H2O) of a polyester produce?
Free carboxylic acid and an alcohol (diol)
What does the alkaline hydrolysis (NaOH/H2O) of a polyamide produce?
Sodium salt and free amines
What does the acid hydrolysis (H+/H2O) of a polyamide produce?
Ammonium salt and free carboxylic acids
