Polyermisation, amines, amides, and amino acids

Question 1

describe an amino acid

Answer 1

• Class of compounds with 2 functional groups a carboxylic acid and an amine group
• When both functional groups are attached to the same carbon atom the compound is called an alpha amino acid
• General formula = RCH(NH2)COOH
• Made up of amino acid monomers bonded together

Question 2

Describe the isoelectric point

Answer 2

• When there is no net electrical charge due to each zwitterion having an intenral balance of charge
• By changing the Ph you later the amino acid so only one is charged this means at low ph there is a lot of hydrogen ions and the carboxylic acid becomes COOH and only the amine group is charged
• However at high ph the amine group becomes NH2 and only the carboxylic acid group is charged

Question 3

Describe the structure of an alpha amino acid

Answer 3

• Carboxylic acid functional group is a weak acid that will partially ionise in water, the nitrogen atom on the amine group has a lone pair of electrons and can act as a base meaning that the amino acid is amphoteric – they can act as a base and an acid, the carboxylic group can react with bases and the amine group can react with acids

Question 4

what is a Zwitterion

Answer 4

• Can form zwitterions this is where the two functional groups exchange a proton and make an internal salt, the carboxylic acid donates a proton to the amino group, two charges cancel each other out and the molecule has no charge

Question 5

How does the carboxylic acid functional group on the amino acid react

Answer 5

• Metal oxidises – neutralisation reaction occurs and the hydrogen atom on the carboxylic acid group is exchanged for a metal ion to product a metal salt, water is also produced in the reaction
• Alkalis – alkalis are soluble bases so a neutralisation reaction occurs, this produces a salt and water
• Carbonates – neutralisation reaction produces a salt, water and carbon dioxide gas, as a gas is evolved effervescence is observed
• Alcohols – reaction produces an ester and releases a molecule of water

Question 6

How does the amine functional group on the amino acid react

Answer 6

• Can react as a base due to the lone pair of electrons on the nitrogen atom, when an acid is added to an amino acid the amine group accepts a proton an this makes an ammonium salt

Question 7

Describe Amides

Answer 7

• Class of compounds with an acyl group attached to an amine group
• General formula = RC(O)NH2
• Made from a carboxylic acid and an amine or ammonia, one or more of the hydrogen atoms have been substituted for an acyl group

Question 8

describe primary amides

Answer 8

the nitrogen atom has two hydrogen atoms and one acyl group attached

Question 9

describe secondary amides

Answer 9

the nitrogen atom has one hydrogen atom, one acyl group and one alkyl group attached

Question 10

describe tertiary amides

Answer 10

nitrogen atom has no hydrogen atoms attached

Question 11

describe polyamides

Answer 11

condensation polymer, very long chain molecule with a repeating pattern of atoms, made from a reaction between a carboxylic acid and an amine and contain a number of secondary amide groups

Question 12

Naming amides

Answer 12

Naming primary amides 
-	Amide such as metanamide 
Naming secondary amides 
-	N-methylethanamide 
-	Name the substituted group first

Question 13

what is polymerisation

Answer 13

is the chemical reaction that results in the production of very long chain molecule with repeating units – there are two types of polymerisation

Question 14

what is addition polymerization

Answer 14

where monomers have at least one C=C bond which breaks and joins the other monomers together, only one type of product from this type of polymerisation

Question 15

what is condensation polymerisation

Answer 15

two different monomers with different functional groups react to form a polymer and release another smaller molecule often water

Question 16

Describe polyesters

Answer 16

• Class of condensation polymer made by the chemical reaction of a dicarboxylic acid and a diol, when the carboxylic acid group on one monomer reacts with the alcohol group on another monomer an ester link R-COO-R is formed between two molecule and produces a long chain molecule

Question 17

Describe polyamides

Answer 17

• Class of condensation polymer made by a chemical reaction of a dicarboxylic acid and a diamine, when the carboxylic acid group on one monomer reacts with the amine group on the other monomer an amide link is formed between the two molecules, this produces a polyamide

Question 18

What is hydrolysis

Answer 18

• Hydrolysis is a chemical reaction in which water breaks bonds

Question 19

Describe hydrolysis

Answer 19

• Slow rate of reaction this is why condensation polymers do not degrade when it rains but it can be achieved in acidic or basic conditions and the rate can be increased by heating

Question 20

Describe the hydrolysis of polyesters

Answer 20

• Undergo in basic and acidic conditions, basic conditions are very fast
  Acid hydrolysis
• When a polyester is reacted with a strong acid the reaction produces a diol and a dicarboxylic acid, has a slow rate of reaction
  Alkali hydrolysis
• When a polyester is reacted with hot sodium hydroxide the reaction produces a diol and the salt of the dicarboxylic acid

Question 21

Describe the hydrolysis of polyamides

Answer 21

Hydrolysis of polyamides
- Polyamides will undergo hydrolysis in acidic and basic conditons, rate of reaction of acid hydrolysis is faster than basic hydrolysis
Acid hydrolysis
- When reacted with a strong aqueous acid the reaction produces a diammonium salt and dicarboxylic acid
Alkali hydrolysis
- When a polyamide is react with hot sodium hydroxide solution the reaction produces the diamine and the salt of a dicarboxylic acid