Polymers and synthesis

Question 1

What is a zwitterion?

Answer 1

At a certain, specific pH, an alpha- amino acid will exist with NH3+ and COO-. Positive and negative charge cancels out.

Question 2

When is a zwitterion formed?

Answer 2

At the isoelectric point (pH value).

Question 3

Why do amino acids have high melting point?

Answer 3

The + and - charges causes the molecules to attract each other electrostatically- more energy needed to break them apart.

Question 4

What is an optical isomer?

Answer 4

• Non-superimposible image of it’s self
• 4 different groups around one carbon
• Stereoisomer

Question 5

What form do optical isomers exist as and what effect does it have?

Answer 5

• They exist in (+) and (-) forms.
• (+) rotates plane polarised light clockwise.
• (-) rotates plane polarised light anti-clockwise.

Question 6

What are the two types of polymers?

Answer 6

Polyesters and polyamides

Question 7

What two type of monomers join together to make a polyester?

Answer 7

diol+ dicarboxylic acid

Question 8

What type of monomers join together to make a polyester?

Answer 8

Hydroxycarboxylic acids

Question 9

What two type of monomers join together to make a polyamide?

Answer 9

Diamine+ dicarboxylic acid

Question 10

What type of monomers join together to make a polyamide?

Answer 10

Amino acids.

Question 11

What is the general formula of an amino acid?

Answer 11

RCH(NH2)COOH

Question 12

What do different R groups do?

Answer 12

May result in different isoelectric points

Question 13

What reactants are used in the production of Terylene and what type of compound is it?

Answer 13

A polyester

Ethan-1,2-diol and Benzene-1,4-dicarboxylic acid

Question 14

What reactants are used in the production of poly lactic acid and what type of compound is it?

Answer 14

A polyester

-Lactic acid

Question 15

What reactants are used in the production of nylon-6,6 and what type of compound is it?

Answer 15

Polyamide

1,6-diaminohexane and hexane-1,6-dicarboxylic acid

Question 16

What reactants are used in the production of Kevlar and what type of compound is it?

Answer 16

Polyamide

Benzene-1,4-dicarboxylic acid and Benzene-1,4-diamine

Question 17

What is the difference between condensation and addition reactions?

Answer 17

Addition:
- Only 1 type of monomer
- Has to contain C=C
Condensation:
- 1 or 2 types of monomers

Question 18

What tow ways are there of breaking down condensation polymers?

Answer 18

Base hydrolysis: NaOH/H2O

Acid hydrolysis: H+/H2O

Question 19

Define biodegradable

Answer 19

Polymer that breaks down completely into CO2 and H2O.

Question 20

Define degradable polymer

Answer 20

Polymer that breaks down into smaller fragments when exposed to light, heat or moisture.

Question 21

What is pharmacological activity?

Answer 21

It depends on whether an optical isomer can fit onto the receptor site of a biological molecule (e.g enzymes).
One optical isomer is active, so need to produce one.

Question 22

Why do optical isomers need to be separated in medicine?

Answer 22

One optical isomer may be active and the presence of the inactive form may decrease activity of active form or be toxic/fatality.

Question 23

What are two examples of drugs which contained harmful optical isomers?

Answer 23

Post thalidomide and Post Seldane

Question 24

What are the advantages of having a single isomer?

Answer 24

• Risks from undesirable side effects are reduced.

- Drug doses are reduced- only the active form is present.

Question 25

How can isomers be separated?

Answer 25

• Complicated separation techniques ( may have similar mp, bp…)
• use enzymes/microorganisms/chromatography (costly and time consuming).

Question 26

What are new methods of making the desired single optical isomer?

Answer 26

• Use enzymes as biological catalysts
• Chiral pool synthesis
• Use of transition element complexes.