Amines Flashcards
What is an amine?
Derived from ammonia molecules and contain a nitrogen atom where hydrogens are replaced with an organic group
Different types of amines
Primary - one C bonded to the N
Secondary - two C bonded to the N
Tertiary - three C bonded to the N
Quaternary - four C bonded to the N
What type of amines are aromatic amines?
Primary
What are quaternary ammonium salts used for?
Cleaning products e.g. shampoo, laundry detergents and washing up liquid
What are cationic surfactants?
Quaternary ammonium salts that have a long hydrocarbon tail
How do cationic surfactants work?
Their non-polar tails are attracted to oil/grease. The polar heads are attracted water. This allows the water and oil to mix
How do amines act as bases?
They have a lone pair of electrons that allows them to accept a proton
How do proteins bond to amines?
Via a dative covalent bond. Both electrons in the bond originate from the lone pair on the nitrogen
What determines the strength of an amine base?
- Availability of lone pair on N
- Higher electron density, more readily available electrons are
- Depends on type of group attached to N
What is the order of base strengths?
Aromatics < Ammonia < Primary aliphatic amines
Why are aromatics the weakest bases?
- Benzene rings pull electrons away from N
- Electron density at N decreases
- Lone pair availability reduced
- NEGATIVE INDUCTIVE EFFECT
Why is ammonia not the strongest base?
There is nothing to push or pull away the electrons so electron density remains stable on N
Why are primary aliphatic amines the strongest bases?
- Alkyl groups push electrons onto N
- Electron density at N increases
- Lone pair availability increases
- POSITIVE INDUCTIVE EFFECT
How are aliphatic amines made?
- Reacting a halogenoalkane with excess ammonia
- Reducing a nitrile
