1. Amines A Nitrogen, containing a lone pair is the key atom Resembles Ammonia where one or more H’s Are replaced by alkyl groups The lone pair participates in the reactivity Of amines Amines are a core part of ‘amino acids’

2. Amines (structure)

3. A fourth group is attached to the nitrogen atom Using the lone pair. This is known as a quaternary Ammonium ion

4. 2-aminoethanol 2-aminopentane TRIS buffer, used widely in biochemistry

5. Other examples: 2-dimethylaminoethanol 2-methylaminoethanol

6. Amine Nomenclature (contd)

7. Aromatic amines • The –NH2 functional group is an amino group, and when this group is a substituent, amino- is used as a prefix • The presence of the amine group increases the reactivity of the aromatic ring

8. Properties of amines: Basicity • Amines are electron pair donors • Bronsted-Lowry bases or lewis bases

9. Difference of boiling pts., similar molecular weights, why ? • H-bonding significantly affects b.p • Amine b.p are generally lower than alcohols • Soluble in water (upto 6 carbons) • Gaseous amines smell like ammonia, liquid amines have a • A characteristic ‘fishy’ smell!!

10. Will 3o amines have higher b.p than 1o amines ?

11. Heterocyclic Nitrogen compounds Heterocycles are common in many naturally derived products

13. Back to basicity of Amines • Basicity depends on: • Availability of Lone pair of electrons • - Is the protonated form of the amine water-soluble? • - Substituent groups on the amine

14. Quarternary ions Note: heterocyclic ammonium ions are named by using –ium instead of -e