Amines Flashcards
How are aliphatic amines prepared?
Nucleophilic substitution with halogenoalkanes and ammonia
How are aromatic amines prepared?
Reduction of nitrobenzene compounds produced after electrophilic substitution
Are amines acids or bases?
Bases
What is the order of base strength between :NH₃, primary amines and primary aromatic amines?
Primary amines, ammonia, primary aromatic amines.
Why do primary amines have a higher base strength than ammonia? (and why are tertiary > secondary > primary)
They have an alkyl group which has an electron releasing effect. This increases the electron density on the N. This makes it a better proton acceptor.
What is the other reactive property of amines (other than being basic)?
Amines are nucleophiles
What is the technical name of a ‘quarternary’ amine?
Quarternary ammonium salt
What are the uses of quarternary ammonium salt?
Antiseptic and hair conditioner
What condition in nucleophilic substitution will increase the amount of primary amine produced?
Excess ammonia
What condition in nucleophilic substitution will increase the amount of quarternary ammonium salt produced?
Excess halogenoalkane
What reaction do acyl chlorides undergo with amines?
Nucleophilic addition elimination
Where are the curly arrows for nucleophilic addition elimination?
- Lone pair on amine to carbon on Cl-C=O
- From C=O double bond to O
- Positive charge on N when attached
- From lone pair on another amine molecule to hydrogen on R₂-N-H attached to acyl chloride
- From lone pair on O in Cl-C-O to C-O bond
- From C-Cl bond to Cl
How stable is :Cl- as a leaving group?
Very stable
What makes aromatic amines less strong than ammonia and primary amines?
Aromatic amines contain a delocalised system which is electron withdrawing, the lone pair on the nitrogen becomes part of the delocalised system, which makes the lone pair less available, weaker base.
