Amine Compound

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Amine Compound
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Amine Compound

• Comment on the hydribrization of the nitrogen
  atom in RNH2 and in Ph-NH2.

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Amine Compound

• The hybridization of RNH2 is sp3 but the
  hybridization of Ph-NH2 is between sp2 and sp3 so
  the bond angle is between 109o-120o.

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Amine Compound

• A. Preparation
• 1. Reduction from nitro-compounds

Other reducing agents Sn / conc. HCl H2 / Ni
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Amine Compound

• A. Preparation
• 2. From acid amidei.ii. (Hofmann degradation)

It will reduce 1 carbon atom in this reaction.
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Amine Compound

• A. Preparation
• 3. From acid nitrile

Other reducing agents H2 / Ni 140oC Na / ethanol
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Amine Compound

• A. Preparation
• 4. From RX

Further substitution give mixture of products.
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Amine Compound

• B. Physical properties
• With fishysmell.
• 2. Soluble in water due to H-bond formation.
• 3. Aromatic amine are liquid with high boiling
  point with a characteristic fishy smell and
  insoluble in water.

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Amine Compound

• C. Chemical properties
• 1. Basic character

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Amine Compound

• C. Chemical properties
• 1. Basic character (contd)

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Amine Compound

• C. Chemical properties
• Basic character (contd)
• Basic strength depends on the availability of
  lone pair e- on N and solubility in water
  (stability of the conjugate cation).

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Amine Compound

• C. Chemical properties
• Basic character (contd)
• Inductive effect
• Due to the alkyl group (e-donating group)
• 3o gt 2o gt 1o gt NH3 BUT
• Ease of solvation of protonated amine
• Due to the formation of H-bond between N-H and
  H2ONH3 gt 1o gt 2o gt 3o
• Overall effect2o ? 1o gt 3o gtNH3

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Amine Compound

• C. Chemical properties
• Basic character (contd)
• Comparing ammonia, CH3NH2 (CH3)2NH, basic
  strength increased as more alkyl groups attached
  to the N atom. Alkyl group is e-donating group
  which makes the lone pair of e- of N more
  available to co-ordinate with a proton.

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Amine Compound

• C. Chemical properties
• Basic character (contd)
• Aromatic amines are less basic strength than
  aliphatic amines. This is because the lone pair
  e- of N can overlap with the pi-molecular orbital
  of the benzene ring. It is thus less available
  to co-ordinate with a proton.

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Amine Compound

• C. Chemical properties
• Basic character (contd)
• For acid amide, it is even less basic strength
  than aromatic amine. This is because the
  negative inductive effect of the CO which makes
  the lone pair e- on N less available. Moreover,
  lone pair e- on N can ovrelap with p-orbitals of
  C.

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Amine Compound

• C. Chemical properties
• Test for amine
• RNH2 HCl ? RNH3Cl- (white fume)

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Amine Compound

• C. Chemical properties
• 2. Alkylation (nuclophilic substitution of RX)

Such method will give mixture of products.
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Amine Compound

• C. Chemical properties
• 3. Acylation (ammonolysis of acid derivative)

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Amine Compound

• C. Chemical properties
• 3. Benzolyation

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Amine Compound

• C. Chemical properties
• 3. AcetylationThe acylating agent is ethanoyl
  chloride CH3COClSuch reaction is used for
  identification of different members of amine.

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Amine Compound

• C. Chemical properties
• 3. Acetylation (contd)The criteria in
  choosing such derivative isa. The reaction with
  little side product easily carried out.b.
  Products are easily crystallized purified.c.
  Melting points between consecutive member
  derivative are large enough for identification.

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Amine Compound

• C. Chemical properties
• 4. With HONO

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Amine Compound

• C. Chemical properties
• For aromatic amine
• Under electrophilic substitutionDiazonium
  coupling

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Amine Compound

• Uses of amines and their derivatives
• Azo-compounds as dyes in dyeing industries.
• Amine derivatives as drugs.

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Amine Compound

• Naming

methanamine
N-methylethanamine
N,N-dimethylmethanamine
2-methylpropan-2-amine
N-ethyl-N-methylpropan-2-amine
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Amine Compound

• Naming

Phenylamine (aniline)
phenylmethanamine
Tetramethylammonium iodide
Ethane-1,2-diamine
N,N-dimethylphenylamine
diphenylamine