Amines (organic ammonia) :NH 3 :NH 2 R or RNH 2 1 o amine(R may be Ar) :NHR 2 or R 2 NH2 o amine :NR 3 or R 3 N3 o amine NR o ammonium salt

Amines are classified by the class of the nitrogen, primary amines have one carbon bonded to N, secondary amines have two carbons attached directly to the N, etc. Nomenclature. Common aliphatic amines are named as “alkylamines”

Salts of amines: change amine  ammonium + anion change aniline  anilinium + anion CH 3 CH 2 CH 2 NH 3 + Cl - n-propylammonium chloride (C 6 H 5 NH 3 ) 2 SO 4 anilinium sulfate

Amines, physical properties: Nitrogen is sp 3 hybridized, amines are polar and can hydrogen bond. mp/bp are relatively high for covalent substances amines are basic and will turn litmus blue insoluble in water (except for four-carbons or less) soluble in 5% HCl “fishy” smell 

RNH 2 + HCl  RNH Cl - water water insoluble soluble RNH OH -  RNH 2 + H 2 O water water solubleinsoluble 1. test for amines 2. can be used to separate amines from neutral or acidic organic compounds

Amines, syntheses: 1.Reduction of nitro compounds Ar-NO 2 + H 2,Ni  Ar-NH 2 2.Ammonolysis of 1 o or methyl halides R-X + NH 3  R-NH 2 3.Reductive amination R 2 C=O + NH 3, H 2, Ni  R 2 CHNH 2 4.Reduction of nitriles R-C  N + 2 H 2, Ni  RCH 2 NH 2 5.Hofmann degradation of amides RCONH 2 + KOBr  RNH 2

1. Reduction of nitro compounds:

2.Ammonolysis of 1 o or methyl halides.

3. Reductive amination: Avoids E2

Reductive amination via the imine.

4.Reduction of nitriles R-C  N + 2 H 2, catalyst  R-CH 2 NH 2 1 o amine R-X + NaCN  R-CN  RCH 2 NH 2 primary amine with one additional carbon (R must be 1 o or methyl)

5. Hofmann degradation of amides

Amines, syntheses: 1.Reduction of nitro compounds1 o Ar Ar-NO 2 + H 2,Ni  Ar-NH 2 2.Ammonolysis of 1 o or methyl halidesR-X = 1 o,CH 3 R-X + NH 3  R-NH 2 3.Reductive aminationavoids E2 R 2 C=O + NH 3, H 2, Ni  R 2 CHNH 2 4.Reduction of nitriles+ 1 carbon R-C  N + 2 H 2, Ni  RCH 2 NH 2 5.Hofmann degradation of amides- 1 carbon RCONH 2 + KOBr  RNH 2

Outline possible laboratory syntheses for each of the following amines, starting with toluene. Use a different method for each compound. First decide which method you are going to use for which compound…

1. nitration 2. ammonolysis 3. Reductive amination 4. Reduction of nitrile 5. Hofmann degradation