6.2.1 & 2 -Amines, Amino acids, Amines & Chirality Flashcards
Naming when NH2 is attached to 1st C
- amine
e. g. hexylamine
Naming when NH2 is attached to middle C
no. where -NH2 is attached
amino
Longest carbon chain
e.g. 3 amino hexane
Naming when NH2 group is attached to 2/3 groups
N- side chain 1 N - side chain 2 - amine
e.g. N - ethyl, N methyl amine
alphabetical order
Primary amines
N attached to one R group, 2 H’s
Secondary amines
N attached to two R groups, 1 H
Tertiary amines
N attached to three R groups, no H’s
Quaternary ammonium salts
Not amines but ammonium salts with NO lone pair on the N
Aromatic amines
Have the N joined directly to the benzene ring
Bonding between amines
Some H bonding between molecules but weaker than in alcohols
No H bonding in 3’ amines
Many simple amines are liquids at rt
What does base strength of amines depend on
How well the N lone pair can accept H+
When is the basicity of an amine higher
When the charge density is higher
Base strength increases from ..
1’ to 3’ amines due to alkyl groups pushing electron density towards the N
Base strength of 4’ amines
Ammonium salts aren’t bases
Why is basicity low in aromatic amines
W/ aromatic amines, NH2 is an ED group so lone pair on N is drawn into delocalised ring, reducing electron density on lone pair
Highest to lowest basicity
3’ > 2’ > 1’ > NH3 > Aromatic
Synthesis of 1’ amines
Nucleophilic substitution
Excess ethanolic NH3 and haloalkane –> 1’ amine and NH4X