140 likes | 335 Views
THE CHEMISTRY OF AMINES. AMINES. CONTENTS Structure and classification Nomenclature Physical properties Basic properties Preparation of amines Reactions of amines. H. H. R. R. R N :. R N :. R N :. +. R N R. H. R. R. R. STRUCTURE & CLASSIFICATION.
E N D
AMINES • CONTENTS • Structure and classification • Nomenclature • Physical properties • Basic properties • Preparation of amines • Reactions of amines
H H R R R N: R N: R N: + R NR H R R R STRUCTURE & CLASSIFICATION Structure Contain the NH2 group Classification primary (1°) amines secondary (2°) amines tertiary (3°) amines quarternary(4°) ammonium salts Aliphaticmethylamine, ethylamine, dimethylamine AromaticNH2 group is attached directly to the benzene ring (phenylamine)
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 onthe chain is indicated by the lowest number. 3-Amino-5-methylhexane 5-Aminoheptanoic acid 3-Amino-2- butanol
Aniline o-Nitroanilinep-Toluidinep-aminophenol p-nitro- N-ethylaniline
Physical Properties of Alcohols Boiling Points of Amines • 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. Solubility Of Amines
Basicity of Amines • 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. CH3-NH-CH3 > NH2-CH3 > NH3 2 ◦ 1 ◦ Ammonia H CH3 N: H
While electron withdrawing substituents decrease basicityas the electron density on N is lowered effective. H C6H5 N: • Aliphatic amines are considerably more basic than aromatics amines. e.g.2: methylamine > ammonia > phenylamine
Preparation of amines 1- Reduction of nitro compounds, nitriles, amides, and oximes