Topic 10 Amines

Question 1

Arrange the following amines in order of increasing basicity (i.e. from lowest pKa to highest pKa):

(i) NH3
(ii) NH4+
(iii) aniline

A. (iii) < (ii) < (i) 
B. (i) < (ii) < (iii)
C. (ii) < (i) < (iii)
D. (i) < (iii) < (ii)
E. (ii) < (iii) < (i)

Answer 1

E. (ii) < (iii) < (i)

Question 2

Arrange the following amines in order of increasing basicity (i.e. from highest pKb to the lowest pKb):

i) aniline
ii) imidazole
iii) indole

A. (iii) < (ii) < (i)
B. (i) < (ii) < (iii)
C. (ii) < (i) < (iii)
D. (i) < (iii) < (ii)
E. (iii) < (i) < (ii)

Answer 2

E. (iii) < (i) < (ii)

Question 3

Covalent addition of chemical groups (bioconjugation) to surface lysines of a protein via an acylation reaction is best conducted at which of the following conditions?
A. pH 5
B. pH 7
C. pH 9

Answer 3

C. pH 9

Question 4

The industrial Haber process can be described as:
N2 + 3 H2 → 2 NH3 H = -92 kJ.mol-1
In relation to this process, which of the following is TRUE?

A. Yield of the product, NH3, will increase as the pressure of reaction is increased.
B. The reaction is endothermic.
C. This reaction proceeds spontaneously at room temperature.
D. The H2 used in this reaction is provided by a coupled, endothermic reaction.
E. Yield of the product, NH3, will increase as
the temperature of reaction is increased

Answer 4

A. Yield of the product, NH3, will increase as the pressure of reaction is increased.

Question 5

Why is the boiling point of amines lower than the boiling point of alcohols?

Answer 5

Amine H-bonds are weaker than alcohol H-bonds

Question 6

How does chloroquine work?

Answer 6

The malaria parasite sits in the food vacuole. Because of the weak bases in amines it moves down a pH gradient into the acidic food vacuole

Question 7

Are amines basic or acidic? Why?

Answer 7

Basic, readily acquire a proton due to the lone pair on the nitrogen

Question 8

Draw withdrawal of nitrogen lone pair via delocalization.

Question 9

Explain His-tag chromatography

Answer 9

6 His residues are artificially added to recombinant protein sequence. The bound protein is eluted from the column with imidazole

Question 10

Draw biconjugation of proteins

Question 11

Draw the o, m, p convention

Question 12

Which of the following statements about amines is FALSE?
A. Amines contain a single non-bonding electron pair that is available for hydrogen bonding.
B. Amine groups are slightly acidic and act as electrophiles.
C. Amine groups are found in the side chains of amino acids arginine, lysine and histidine.
D. The nitrogen atom in amines is sp3 hybridized and adopts a trigonal pyramidal conformation.
E. Amines are often prepared commercially by the Gabriel synthesis.

Answer 12

B. Amine groups are slightly acidic and act as electrophiles.

Question 13

Arrange the following amines in order of increasing basicity (i.e. from largest pKb to lowest pKb):

i) NH3
ii) methylamine (CH3NH2)
iii) phenylamine (aniline)

a. (iii) < (ii) < (i)
b. (i) < (ii) < (iii)
c. (ii) < (i) < (iii)
d. (i) < (iii) < (ii)
e. (iii) < (i) < (ii)

Answer 13

e. (iii) < (i) < (ii)