1. THE CHEMISTRY OF AMINES By Dr. Nahed Nasser

2. AMINES CONTENTS Structure and classification Nomenclature Physical properties Basic properties Preparation of amines Reactions of amines

3. STRUCTURE & CLASSIFICATION StructureContain the NH 2 group Classification primary (1°) amines secondary (2°) amines tertiary (3°) aminesquarternary (4°) ammonium salts Aliphaticmethylamine, ethylamine, dimethylamine Aromatic NH 2 group is attached directly to the benzene ring (phenylamine) R N : H H R H R R R + R N R R

4. NOMENCLATURE Common names: Derived by listing the names of the groups surrounding the nitrogen and adding the suffix amine Methyl amine Benzyl methyl amine Trimethyl amine Tetramethyl ammonium bromide IUPAC names: Derived by considering the amino group as a substituent and its position on the chain is indicated by the lowest number. 3-Amino-5-methylhexane 5-Aminoheptanoic acid 3-Amino-2- butanol

5. 5 Aniline o-Nitroaniline p-Toluidine p-aminophenol p-nitro- N-ethylaniline

6. Because they possess a polar N-H bond, primary and secondary amines are capable of forming intermolecular hydrogen bonds among their molecules; therefore they have: Higher boiling points than alkanes but lower than alcohols. All amines are capable of forming hydrogen bonds with water thus they are soluble in water. Physical Properties of Alcohols Boiling Points of Amines Solubility Of Amines

7. 7 Because the nitrogen atom of 1 ◦, 2 ◦ and 3 ◦ amines has a lone pair of electrons; amines can be lone pair donors and proton acceptors from acids (i.e. they have basic properties) to form ammonium salt. a proton acceptor Base strength :depends on the availability of the lone pair and its ability to pick up protons The greater the electron density on the N, the better it can pick up protons This is affected by the degree of substitution ; electron donating groups on N atom increase the bacisity : eg. CH 3 -NH-CH 3 > NH 2 -CH 3 > NH 3 2 ◦ 1 ◦ Ammonia 2 ◦ 1 ◦ Ammonia Basicity of Amines CH 3 N : H H

8. 8 Aliphatic amines are considerably more basic than aromatics amines. While electron withdrawing substituents decrease basicity as the electron density on N is lowered effective. e.g.2: methylamine > ammonia > phenylamine e.g.2: methylamine > ammonia > phenylamine C 6 H 5 N : H

9. Preparation of amines 1- Reduction of nitro compounds, nitriles, amides, and oximes

10. 2- Alkylation of ammonia

11. 3- Hoffman degradation of Amides

12. Reactions of Amines