Chemistry 20 Chapter 8 Amines Amines Are derivatives

Chemistry 20 Chapter 8 Amines

Amines: • Are derivatives of ammonia NH 3. • Contain N attached to one or more alkyl (Aliphatic amine) or aromatic groups (Aromatic amine). -NH 2 amino group NH 2 CH 3 -NH-CH 3

Amines are classified into three groups: depending on the number of carbon groups bonded to nitrogen. CH 3—NH 2 CH 3—NH Primary 1° Secondary 2° CH 3—N—CH 3 Tertiary 3°

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 (-NH 2) on the parent chain. NH 2 CH 3 -CH-CH 3 3 2 1 2 -propanamine 3 CH 3 -CH-CH-CH 3 1 2 Cl 6 5 4 3 2 1 4 3 -chloro-2 -butanamine 1, 6 -hexanediamine

Naming Amines Common name Names of alkyl groups (In alphabetical order) + “amine” CH 3—CH 2—NH 2 ethylamine CH 3—NH —CH 3 dimethylamine CH 3 | CH 3—N—CH 2—CH 3 ethyldimethylamine

Aniline (common name) NH 2 Aniline NH 2 2 1 3 4 NH 2 2 1 3 CH 3 4 Cl NO 2 4 -Nitroaniline 2 1 3 -Methylaniline 3 CH 3 4 -Chloro-3 -methylaniline

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”. aniline CH 3 -N-CH 2 -CH 3 N, N-Dimethylethanamine

Heterocyclic amines When N is one of the atoms of a ring. N H Pyrrolidine CH 3 H Pyridine Nicotine

Physical properties of Amines 1. They have unpleasant odors (rotting fish like ammonia). 2. 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). 4. Boiling points: Hydrocarbons< Amines < Alcohols 5. Almost soluble in water (hydrogen bonding).

Chemical properties of Amines They are weak bases (like ammonia): react with acids. (to form water-soluble salts) H CH 3 N. . H + . . H –. . O–H H CH 3 N + H -. . . O – H H Some amines present in our blood and make it approximately basic (p. H = 7. 4).

Chemical properties of Amines Aliphatic amines are weak bases by comparison with inorganic bases such as Na. OH, they are strong bases among organic compounds. Aliphatic amines are stronger bases than aromatic amines. (slightly stronger than NH 3)

Examples Complete each acid-base reaction and name the salt formed.

Examples Complete each acid-base reaction and name the salt formed. Solutions: