Amides

Question 1

Explain what is meant by the isoelectric point

Answer 1

This is a pH where the amino acid has no net charge as it is balanced. Here the amino acid is at its zwitterion state

Question 2

Explain the structures for amides and nomenclature of amides

Answer 2

Suffix - amide
As an R group is attached to the nitrogen, a prefix of N is added

Therefore secondary amide:
N-methylethanamide
Tertiary amide:
N,N-dimethylethanamide

Question 2

Explain how you would go about forming an amide

Answer 2

Acyl chloride + excess ammonia

Question 4

Explain the esterification reaction

Answer 4

Amino acid + R-OH —> aminoester formed + H2O

This is a dehydration / condensation reaction

Question 5

State the general formula for amino acids

Answer 5

RCH2(NH2)COOH

Question 9

Explain why aminos acids are described as amphoteric

Answer 9

Can act as both an acid and base

Question 10

Explain the 3 neutralisation reactions of amino acids

Answer 10

If pH low; H added to the basic part of amino acid to form NH3+
If pH neutral; H swapped from OH to NH2, forming O- and NH3+
If pH high; H removed from acidic part of amino acid to form O-

Question 11

Explain what is meant by a zwitterion

Answer 11

2 groups exchange a proton to form an internal salt of neutral charge