CD (from PMT Notes)

Question 1

What are dyes?

Answer 1

Coloured compounds that chemically bond to a substrate and absorb light in the visible spectrum.

Question 2

What is a chromophore?

Answer 2

An atom or chemical group responsible for the colour of a compound.

Question 3

Which functional groups can modify a chromophore?

Answer 3

• -OH
• -NH2
• -NR2

Question 4

How do dyes bond to fibers?

Answer 4

By intermolecular forces, covalent bonds, and ionic bonds.

Question 5

What groups in fibers attract dyes?

Answer 5

• -COOH
• -SO3H
• -NH groups

Question 6

What are auxochromes?

Answer 6

Functional groups that alter the solubility of a dye, such as carboxylic acid, sulfonic acid, amino, and hydroxyl groups.

Question 7

What are triglyceride esters?

Answer 7

Esters formed from glycerol and carboxylic acids through esterification.

Question 8

How does the chain length of carboxylic acids in triglycerides vary?

Answer 8

Ranges from C4 to C22.

Question 9

Why do oils have a lower melting point than fats?

Answer 9

Oils are more unsaturated, containing more carbon-carbon double bonds.

Question 10

What is the effect of carbon-carbon double bonds on oil molecules?

Answer 10

They alter the shape, preventing close packing and reducing melting point.

Question 11

What are the main types of reactions?

Answer 11

• Addition
• Substitution
• Oxidation
• Reduction
• Hydrolysis
• Condensation
• Elimination

Question 12

What defines an aromatic compound?

Answer 12

Compounds that contain a benzene ring.

Question 13

What is the molecular formula of benzene?

Answer 13

C6H6.

Question 14

What stabilizes benzene compared to other molecules?

Answer 14

The delocalised electron ring structure.

Question 15

What is the enthalpy change of hydrogenation for benzene?

Answer 15

-208 kJ mol-1.

Question 16

What does the bond length evidence from X-ray diffraction show about benzene?

Answer 16

All bond lengths between carbon atoms are the same.

Question 17

Why does benzene not undergo electrophilic addition reactions?

Answer 17

It would break the stable delocalised ring of electrons.

Question 18

What type of reaction does benzene undergo instead of electrophilic addition?

Answer 18

Electrophilic substitution reactions.

Question 19

What is halogenation in relation to benzene?

Answer 19

A type of electrophilic substitution where benzene reacts with halogens in the presence of a catalyst.

Question 20

What is nitration in the context of benzene?

Answer 20

An electrophilic substitution where NO2+ is the electrophile.

Question 21

What is produced during the nitration of benzene?

Answer 21

Benzenesulfonic acid.

Question 22

What does Friedel-Crafts acylation involve?

Answer 22

The nucleophilic attack of the benzene ring on acyl chlorides.

Question 23

What are diazonium salts?

Answer 23

Salts containing the diazonium ion, R-N2+.

Question 24

What happens when diazonium salts react with phenol?

Answer 24

They form azo compounds.

Question 25

What is the result of oxidizing aldehydes under reflux conditions?

Answer 25

They produce carboxylic acids.

Question 26

What reagents are used to test for aldehydes?

Answer 26

* Tollen's reagent * Fehling's solution

Question 27

What do hydroxynitriles result from?

Answer 27

Nucleophilic addition reactions with the :CN- nucleophile.

Question 28

What is a polyfunctional compound?

Answer 28

An organic compound containing two or more functional groups.

Question 29

What factors must be considered when designing a synthetic pathway?

Answer 29

* Product yield * Reaction setup * Conditions * Process type * Hazards * Cost * Isomer formation

Question 30

What is a key factor a chemist must consider when designing a synthetic pathway?

Answer 30

Product yield ## Footnote Related to Le Chatelier’s principle.

Question 31

What are the components of reaction setup in synthetic pathways?

Answer 31

* Catalysts * Reagents * Conditions (temperature, pressure, concentrations) ## Footnote These factors influence the efficiency and outcome of the synthesis.

Question 32

What types of processes can be involved in synthetic pathways?

Answer 32

* Batch * Continuous ## Footnote The choice depends on the nature of the reaction and production needs.

Question 33

What is one hazard a chemist must consider when designing a synthetic pathway?

Answer 33

Hazards ## Footnote Safety considerations are crucial in chemical synthesis.

Question 34

What is an important consideration regarding the formation of isomers in drug synthesis?

Answer 34

Many drug targets are enzymes that are stereospecific and react with one enantiomer only ## Footnote Ideally, the synthetic pathway should produce only this enantiomer.

Question 35

What causes color in organic molecules?

Answer 35

Carbon-carbon double bonds or unsaturation ## Footnote Electrons in π bonds can be promoted to higher energy orbitals when electromagnetic radiation is absorbed.

Question 36

What is the role of conjugation in color in organic molecules?

Answer 36

It lowers the energy required to promote an electron ## Footnote This allows energy absorption from the UV to visible region of the electromagnetic spectrum.

Question 37

What do we see as the color of a molecule?

Answer 37

The complementary color of the wavelengths absorbed ## Footnote This is due to specific wavelengths being reflected from the molecule.

Question 38

What is the stationary phase in gas-liquid chromatography?

Answer 38

A high boiling point liquid adsorbed onto a solid ## Footnote This is packed into a thin coiled column.

Question 39

What is used as the mobile phase in gas-liquid chromatography?

Answer 39

A high pressure gas (inert carrier gas like helium) ## Footnote This gas helps to transport the sample through the column.

Question 40

What does gas-liquid chromatography help to separate?

Answer 40

Mixtures of volatile liquids ## Footnote These are fed into the system as vapours.

Question 41

What is recorded for each component in a mixture during gas-liquid chromatography?

Answer 41

A retention time ## Footnote Each substance has a unique retention time that aids in identification.

Question 42

What additional analysis can be performed alongside gas-liquid chromatography to identify compounds?

Answer 42

Mass spectrum ## Footnote This provides further identification of emerging compounds.