Naming and Properties of Amines

Mini notes on how to name and the properties of amines

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Naming Amines - Method 1

Split substance into groups and name each group individually

- first part: depends on carbon chain e.g. CH3CH2 would be ethyl

- second part: refer to NH2 as amine


Examples

1) CH3NH2 = methylamine

- first part: CH3 => methyl

- second part: NH2 => amine

2) C2H5NH2 => ethylamine

- first part: C2H5 => ethyl

- second part: NH2 => amine

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Naming Amines - Method 2

Count the number of carbons in the longest carbon chain - e.g. 4 carbons = butane

See which carbon the NH2 group is attached to => amino


Examples

1) CH3CHNH2CH3 = 2 amino propane

- first part => CH3-CH-CH3: propane

- second part => CH3-CH-NH2: 2 amino

2) CH3CNH2(CH3)CH3 = 2-methyl-2-aminopropane

- first part => CH3-C-CH3: propane

- second part => CH3-C-NH2: 2 amino

- additional part => CH3-C-NH2-(CH3): 2 methyl

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Primary, Secondary and Tertiary Amines

Primary Amines

When the amino group is attached to one alkyl group

E.g. CH3-NH2 => methylamine


Secondary Amines

When the amino group is attached to two alkyl groups

E.g. CH3-NH-CH3CH2 => ethylmethylamine


Tertiary Amines

When the amino group is attached to three alkyl groups

E.g. CH3-N-CH3-CH3 => trimethylamine

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Properties of Amines

  • Similar to those of ammonia => most properties due to lone pair of electrons on N atom
  • Lone pair responsible for substance being:

1) Very soluble in water => (hydrogen bonding)

2) Base => (accepts protons - due to lone pair)

3) Ligand

4) Nucleophille (donates pair of electrons)


  • Amines with small alkyl groups are soluble but ones with larger groups are less soluble
  • This is because alkyl groups disrupt hydrogen bonding
  • Smaller amines are more soluble as hydrogen bonding is less disrupted
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