Amines/Amides/Amino Acids

Question 1

Inductive effect

Answer 1

Benzene rings - draw electron density away from the nitrogen making the lone pair ‘less available’
Alkyl groups - push electron density towards the nitrogen atom making the lone pair ‘more available’. More alkyl groups means more ‘pushing’.
Therefore, aliphatic amines are stronger bases and aromatic amines are weaker bases.

Question 2

Naming NSUB amides

Answer 2

When naming N-substituted amides, they are treated in a similar way to esters. The prefix indicates the length of the carbon chain bonded to the nitrogen atom only and the suffix indicates the carbon chain which contains the carbonyl bond.

Question 3

Polyamides

Answer 3

Polyamides are condensation polymers generally formed in a reaction between a dicarboxylic acid and a diamine. A molecule of water is removed, leaving an amide linkage.

Question 4

Kevlar Monomers

Answer 4

Kevlar is another common polyamide made from benzene-1,4-dicarboxylic acid and 1,4-diaminobenzene.

Question 5

Explain Zwitterions

Answer 5

The two functional groups within a single molecule mean that amino acids can react as both acids and bases depending on the conditions of the reaction.
In acidic conditions (low pH), the COO- group is more likely to accept a hydrogen ion, producing a positive (acidic) end to the molecule.

Zwitterions form at the isoelectric point, which is the pH at which the overall charge of the
molecule is zero.

Question 6

Proteins

Answer 6

Proteins are another form of condensation polymer formed from sequences of amino acids
joined together by peptide bonds. Proteins can be hydrolysed into their constituent amino
acids, which can then be separated and identified by thin-layer chromatography.

Question 7

Peptide Bond

Answer 7

O
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C —- N
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H