Assignment 1:

Assignment covers the material presented in Modules Five and Six.

1. a) What is the origin of the name aromatic hydrocarbons? Give three examples of aromatic hydrocarbons.

b) Briefly describe the structural characteristics of benzene.

2. Find exact names for the following structures using ortho-, mew-, para-descriptors and the numbering system, where appropriate.

3. Explain the mechanism of an electrophilic aromatic substitution reaction using the conversion of benzene to chlorobenzene as an example (chlorination with C12 in presence of FeCI3).

4. Find the structure and name of the products formed in the following reactions:

5. a) What do we understand by sulfa drugs?

b) Describe the structure of acetylsalicylic acid, also known as Aspirin. List three medicinal properties of Aspirin.

6. a) Give the names of the following alcohols. Indicate if the alcohols are primary, secondary, or tertiary alcohols.

b) What is the IUPAC name for the alcohols commonly known as
i) grain alcohol?
ii) wood alcohol?
iii) rubbing alcohol?

7. a) Describe the structural requirements for hydrogen bonding.
b) Illustrate hydrogen bonding as it occurs
i) between ethanol molecules
ii) between ethanol and water molecules

8. Complete the following table. Give both the structure and/or the exact name of the starting material and of the product.

9. a) Briefly outline the production of ethanol by the fermentation process.
b) Describe the chemical basis of the breathalyser test.
e) What is fetal alcohol syndrome?

10. a) Explain briefly the use of ethylene glycol in antifreeze mixtures.

b) Describe the source of glycerol and its use in the manufacture of explosives.

c) Outline the use of ethers in gasoline additives.

Assignment 2:

Assignment covers the material presented in Modules Seven and Eight.

1. Explain what we understand by the following terms:
i) constitutional isomerism
ii) geometrical isomerism
iii) stereoisomerism
iv) configuration
v) conformation
vi) chirality

2. Give the structure and name of all isomers having the following molecular formula:
i) C₃H₈O
ii) C₃H₆O
iii) C₃H₆O₂

3. Describe what we understand by optical activity and how it can be determined.

4. Chemical reduction of pyruvic acid leads to lactic acid with zero optical rotation. In contrast, reduction of pyruvic acid using the yeast enzyme lactic reductase leads to a material with

[α]_D²² = -2.6^o

while reduction using the muscle enzyme lactic dehydrogenase leads to a material with

[α]_D²² = +2.6^o

Explain.

5. Indicate if the following structures possess optical activity. If affirmative, give their name indicating chirality using the (R)/(S) notation.

To help in naming a) and b), use your molecular set and build the molecules.

6. a) Describe the Fehling test in chemical terms.

b) Which of the following compounds would give a positive Fehling test?
i) methanal
ii) butanone
iii) 5-hydroxypentanal
iv) glucose
v) sucrose
vi) lactose

7. a) Illustrate a nucleophilic addition reaction to a carbonyl group using the formation of the cyclic hemiacetal of 5-hydroxypentanal as an example.

b) Cyclization of 5-hydroxypentanal leads to the formation of two stereoisomers. Explain.

8. Explain the following special terms used in carbohydrate chemistry:

i) carbohydrate
ii) monosaccharide
iii) polysaccharide
iv) aldose
v) p-anomer
vi) glycosidic bond

9. Describe the structural characteristics of glucose, fructose, and galactose.

10. a) Starch and cellulose are important plant polysaccharides. Outline briefly their structural differences.

b) Contrast the structural features of table sugar and milk sugar.