Amines
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What compound are amines derived from
Ammonia
What is the functional group of an amine
NH2
What is a primary amine
Where 1 carbon group is bonded to the N atom
What is a secondary amine
Where 2 carbon groups are bonded to the N atom
What is a tertiary amine
Where 3 carbon groups are bonded to the N atom
What is a quaternary ammonium salt
Where 4 carbon groups are bonded to the N atom, causing a positive charge on the molecule
What are non aromatic amines known as
Aliphatic amines
Give 3 uses of quaternary amine salts
Used to make shampoo, laundry detergents, washing up liquids
What are cationic surfactants
Quaternary amine salts which have a long ‘tail’/1 long hydrocarbon group
Explain how cationic surfactants act to remove oil and grease
The non-polar tail is attracted to the oil or grease. The polar head will be attracted to the water. This now allows the water and oil to mix and removes grease from clothing, skin. dishes etc (essentially works by trapping the oil between the cationic surfactants, which allows the oil and the water to mix)
Explain how cationic surfactants act to soften hair
They have a positive ammonium ion which is attracted to the negatively charged fibres and hair. This removes static so is used in conditioners etc
How do amines act as a base
They have a lone pair on the N which allows them to accept a proton (BLB)
How do protons bond to an amine
They bond via a dative covalent bond (both electrons come from lone pair on N) Only when acting as a base and accepting H+ but not in NH3, they are covalent bonds
How many bonds does N form when its neutral
3 (e.g.NH3)
What type of base is an amine
A weak base
List the strength of these amines from strongest to weakest NH3 Primary aliphatic amines Primary aromatic amines
Primary aliphatic amines NH3 Primary aromatic amines
What determines the strength of an amine as a weak base
The availability of the lone pair of electrons on the nitrogen
Explain why primary aliphatic amines are the strongest base (out of the amines)
Alkyl groups have a positive inductive effect This pushes electron density towards the N atom Therefore the lone pair on the nitrogen is more available for protonation or donation
If a lone pair on an amine is being protonated, what is it acting as
A base
If a lone pair on an amine is being donated, what is it acting as
A nucleophile
Explain why primary aromatic amines are the weakest kind of base (out of the amines)
The lone pair on N is DELOCALISED INTO THE BENZENE RING Therefore electron density on the N atom decreases So the lone pair is less available for protonation or donation
What is electron density on the N atom in an amine dependent on
The type of group bonded to the N atom
What are the 2 ways to make a primary aliphatic amine
1: Reacting a halogenoalkane in excess NH3 2: Reducing a nitrile
Name and outline the mechanism by which ammonia is turned into a primary amine through 1-bromopropane
Nucleophilic substitution
