160 likes | 578 Views
Chemistry 20. Chapter 8 Amines. Amines. Amines: Are derivatives of ammonia NH 3 . Contain N attached to one or more alkyl (Aliphatic amine) or aromatic groups (Aromatic amine). CH 3 - NH 2 CH 3 - NH - CH 3. -NH 2 amino group. NH 2. Amines. Amines are classified into three groups:
E N D
Chemistry 20 Chapter 8 Amines
Amines • Amines: • Are derivatives of ammonia NH3. • Contain N attached to one or more alkyl (Aliphatic amine) or aromatic groups (Aromatic amine). • CH3-NH2CH3-NH-CH3 -NH2 amino group NH2
Amines Amines are classified into three groups: depending on the number of carbon groups bonded to nitrogen. CH3 CH3 CH3—NH2 CH3—NH CH3—N—CH3 Tertiary 3° Secondary 2° Primary 1°
NH2 NH2 CH3-CH-CH3 CH3-CH-CH-CH3 Cl Naming Amines IUPAC name – 1° amines • The same method as we did for alcohols. • - Drop the final “-e” of the parent alkane and replace it by “-amine”. • - Use a number to locate the amino group (-NH2) on the parent chain. 3 1 5 3 2 4 6 1 2 4 3 1 2 2-propanamine 3-chloro-2-butanamine 1,6-hexanediamine
Naming Amines Common name Names of alkyl groups (In alphabetical order) + “amine” CH3—CH2—NH2 ethylamine CH3—NH —CH3 dimethylamine CH3 | CH3—N—CH2—CH3 ethyldimethylamine
Aniline (common name) NH2 Aniline NH2 NH2 NH2 2 2 1 1 2 1 CH3 3 3 3 4 CH3 4 Cl NO2 3-Methylaniline 4-Nitroaniline 4-Chloro-3-methylaniline
CH3 CH3-N-CH2-CH3 aniline Naming Amines IUPAC name – 2° and 3° amines • Take the largest group bonded to nitrogen as the parent amine. • Name the smaller group(s) bonded to nitrogen, and show their locations on nitrogen by using the prefix “N”. N,N-Dimethylethanamine
N CH3 H H Heterocyclic amines When N is one of the atoms of a ring. Pyrrolidine Pyridine Nicotine
Physical properties of Amines • They have unpleasant odors (rotting fish like ammonia). • They are polar compounds. • Difference in electronegativity between N - H (3.0 – 2.1 = 0.9) • 3. 1° and 2° amines have hydrogen bonds (N-H). • Weaker than alcohols (O-H). • 3° amines do not form hydrogen bonds (no H atom). • Boiling points: Hydrocarbons< Amines < Alcohols • Almost soluble in water (hydrogen bonding).
H H . . . . - . . . . + . . . . CH3 + CH3 N N H H – O – H O – H H H Chemical properties of Amines They are weak bases (like ammonia): react with acids. (to form water-soluble salts) Some amines present in our blood and make it approximately basic (pH = 7.4).
Chemical properties of Amines Aliphatic amines are weak bases by comparison with inorganic bases such as NaOH, they are strong bases among organic compounds. Aliphatic amines are stronger bases than aromatic amines. (slightly stronger than NH3)
Examples • Complete each acid-base reaction and name the salt formed.
Examples • Complete each acid-base reaction and name the salt formed. Solutions: