1. Amines
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2. Outline Structure and Classification Nomenclature Physical Properties
Preparation
Reaction
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3. Structure and Classification
Amines are organic derivatives of ammonia in which one or more hydrogens are replaced with alkyl or aryl groups.
Amines are further divided into aliphatic and aromatic amines.
It has high degree of biological activity, many amines are used as drugs and medicines.
Amines are classified as primary, secondary, or tertiary, depending on the number of carbon atoms bonded directly to nitrogen. In a heterocyclic amine, the nitrogen atom is part of an aliphatic or aromatic ring.
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4. Nomenclature of amines A.Common Name of amines
Common Names are formed from the names of the alkyl groups bonded to nitrogen, followed by the suffix -amine. The prefixes di-, tri-, and tetra- are used to describe two, three, or four identical substituents.
Methylamine Benzyl methyl amine Trimethyl amine
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5. B. IUPAC nomenclature of amines
The IUPAC nomenclature for amines is similar to that for alcohols. The longest continuous chain of carbon atoms determines the root name. The - e ending in the alkane name is changed to -amine, and a number shows the position of the amino group along the chain. Other substituents on the carbon chain are given numbers, and the prefix N- is used for each substituent on nitrogen.
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6. Naming Of Aromatic Amines
Some common arylamines have the following names:
Aniline
(benzenamine)
o-Toluidine m-Aminophenol
p-Anisidine
(4-methoxybenzenamine)
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7. Physical Properties of Amines Solubility
Amines are strongly polar because the large dipole moment of the lone pair of electrons adds to the dipole moments of the C-N and H-N bonds. Primary and secondary amines have N-H bonds, allowing them to form hydrogen bonds. Pure tertiary amines cannot engage in hydrogen bonding because they have no N-H bonds. They can, however, accept hydrogen bonds from molecules having O￢H or N￢H bonds.
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8. Boiling point
Because nitrogen is less electronegative than oxygen, the N-H bond is less polar than the O-H bond. Therefore, amines form weaker hydrogen bonds than do alcohols of similar molecular weights. Primary and secondary amines have boiling points that are lower than those of alcohols, yet higher than those of ethers of similar molecular weights. With no hydrogen bonding, tertiary amines have lower boiling points than primary and secondary amines of similar molecular weights.
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9. Basicity of Amines: Amine Salts
Amines are relatively weak bases. Most are stronger bases than water but are far weaker bases than hydroxide ions, alkoxide ions, and alkanide anions.
Aromatic amines less basic than aliphatic amines
Electron donating (releasing) groups on N atom increase the basicity
Electron withdrawing groups decrease the basicity
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10. Amine’s 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 H2, Ni  RCH2NH2
Hofmann degradation of amides
RCONH KOBr  RNH2
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11. 1. Reduction of nitro compounds
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12. 340 Chem 1st 1439

13. 2. Ammonolysis of 1o or methyl halides
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16. SN2 Reactions of Alkyl Halides
Ammonia and other amines are good nucleophiles
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17. 3. Reductive amination
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19. Reductive amination via the imine.
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21. 4. 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)
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22. Examples
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23. 5. Hofmann degradation of amides
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24. Outline possible laboratory syntheses for each of the following amines, starting with toluene. Use a different method for each compound.
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25. Hofmann and Curtius Rearrangements
Carboxylic acid derivatives can be converted into primary amines with loss of one carbon atom by both the Hofmann rearrangement and the Curtius rearrangement
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26. Hofmann rearrangement
deprotonation of the amide by the base to form an anion which then attacks the halogen to form a N-haloamide.
2. deprotonation by the base provides an anion that rearranges to an isocyanate intermediate and releases a halide anion.
3. The isocyanate is attacked by water which after a series of proton transfer step results in a zwitterionic intermediate, containing an ammonium cation and a carboxylate anion.
4. Thermal conditions result in the explosion of carbon dioxide gas and quenching of the ammonium cation to the amine product
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27. Curtius rearrangement
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28. Amine Reactions Reaction as Bases: Salt Formation Amide Formation
Reaction with Nitrous Acid
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29. Amine Reactions with Nitrous Acid
Primary amines: Diazotization
Secondary Amines: Nitrosamine formation
Tertiary Amines: C-nitroso com
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30. Mechanism of Diazonium salt formation 1
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31. Mechanism of Diazonium salt formation 2
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32. Diazonium Salt Reactions
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