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

Amines (organic ammonia) :NH 3 :NH 2 R or RNH 2 1 o amine (R may be Ar) :NHR 2 or R 2 NH 2 o amine :NR 3 or R 3 N 3 o amine NR 4 + 4 o ammonium salt.

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

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  1. Amines (organic ammonia) :NH3 :NH2R or RNH2 1o amine (R may be Ar) :NHR2 or R2NH2o amine :NR3 or R3N 3o amine NR4+ 4o ammonium salt

  2. NB 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”

  3. Salts of amines: change amine  ammonium + anion change aniline  anilinium + anion CH3CH2CH2NH3+Cl- n-propylammonium chloride (C6H5NH3)2SO4 anilinium sulfate

  4. Amines, physical properties: Nitrogen is sp3 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 

  5. RNH2 + HCl  RNH3+ + Cl- water water insoluble soluble RNH3+ + OH- RNH2 + H2O water water soluble insoluble 1. test for amines 2. can be used to separate amines from neutral or acidic organic compounds

  6. Amines, syntheses: • Reduction of nitro compounds • Ar-NO2 + H2,Ni  Ar-NH2 • Ammonolysis of 1o or methyl halides • R-X + NH3 R-NH2 • Reductive amination • R2C=O + NH3, H2, Ni  R2CHNH2 • Reduction of nitriles • R-CN + 2 H2, Ni  RCH2NH2 • Hofmann degradation of amides • RCONH2 + KOBr  RNH2

  7. 1. Reduction of nitro compounds:

  8. Ammonolysis of 1o or methyl halides.

  9. 3. Reductive amination: Avoids E2

  10. Reductive amination via the imine.

  11. Reduction of nitriles • R-CN + 2 H2, catalyst  R-CH2NH2 • 1o amine • R-X + NaCN  R-CN  RCH2NH2 • primary amine with one additional carbon • (R must be 1o or methyl)

  12. 5. Hofmann degradation of amides

  13. Amines, syntheses: • Reduction of nitro compounds 1o Ar • Ar-NO2 + H2,Ni  Ar-NH2 • Ammonolysis of 1o or methyl halides R-X = 1o,CH3 • R-X + NH3 R-NH2 • Reductive amination avoids E2 • R2C=O + NH3, H2, Ni  R2CHNH2 • Reduction of nitriles + 1 carbon • R-CN + 2 H2, Ni  RCH2NH2 • Hofmann degradation of amides - 1 carbon • RCONH2 + KOBr  RNH2

  14. 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…

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

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