Chapter 27 - Amines, Amino Acids and Polymers

Question 1

What are amines?

Answer 1

If you replace one or more of the Hydrogens in ammonia with an organic group, you get an amine.

Question 2

What are the different types of amines?

Answer 2

1) if 1 hydrogen is replaced it is a primary amine
2) if 2 hydrogens are replaced it is a secondary amine
3) if 3 hydrogens are replaced it is a tertiary amine
4) if a fourth amine group is added, it becomes an quarternary ammonium ion

Question 3

How do you name amines?

Answer 3

The suffix is amine, and the prefix is the organic groups attached. For example, an amine with a methyl and propyl group attached is called methylpropylamine.

Question 4

Why are amines considered bases?

Answer 4

In amines, the lone pair of electrons on the nitrogen atom can form a dative bond with a H+ ion. The amine donates its lone pair of electrons and “accepts” the proton.

Question 5

Reaction between amines and acids?

Answer 5

Amines are neutralised by acids to form ammonium salts.

Example: methylamine + hydrochloric acid forms methylammonium chloride

CH3NH2 + HCl -> CH3NH3+Cl-

Question 6

What makes amines a stronger base?

Answer 6

The more alkyl groups substituted onto the N atom in place, the more electron density is pushed onto the N atom. This is due to the inductive effect of alkyl groups compared to H atoms, so the more alkyl groups the stronger the base. NH3 is more BASIC than aromatic amine.

Question 7

How do you form primary amines + mechanism?

Answer 7

Ammonia (NH3) reacts with haloalkanes to form primary amines. The overall reaction is nucleophillic substitution. The ammonia acts as the nucleophile as it has a lone pair on the nitrogen atom.

This reaction forms a primary amine and an ammonium salt
Example: 1-chloropropane + NH3 -> propylamine + ammonium chloride (NH4+Cl-)

Question 8

What are the reaction conditions to form primary amines?

Answer 8

1) ethanol is used as a solvent
2) excess ammonia is used

Question 9

How do you form secondary and tertiary amines?

Answer 9

The primary amines reacts further with the haloalkane to form secondary amines and that reacts with the haloalkanes to form tertiary amines. Further substitution takes place.

Question 10

How do you produce aromatic amines?

Answer 10

1) you heat the nitrobenzene under reflux with tin and concentrated hydrochloric acid. This forms an ammonium salt.

2) then to turn the salt into an aromatic amine, you need to add NaOH (sodium hydroxide solution).

The balanced equation

Nitrobenzene + 6(H) -> phenylamine + 2H2O

Question 11

What are amides?

Answer 11

They are carboxylic acid derivatives. They contain the functional group -CONH2

Question 12

How do you name amides?

Answer 12

All amides have the suffix -amide.
A primary amide is when the there are no alkyl groups attached to the amide functional group. So for a 3 carbon chain the name would be propanamide.

A secondary amides have a prefix, which describes the alkyl group attached to the nitrogen atom and a suffix, which describes the alkyl group attached to the C=O atom. So if there was an ethyl attached to the nitrogen and a propyl attached to the C=O it would be N-ethylpropanamide,

Question 13

How do you form amides?

Answer 13

Reaction of acyl chloride with ammonia and amines.

Question 14

What is an amino acid?

Answer 14

An amino acid has two functional groups. An NH2 group (amine) and a COOH group (carboxyl). Alpha amino acids are where both the amine and carboxyl group are attached to the same carbon atom.

Question 15

Reaction of amino acid + sodium hydroxide?

Answer 15

Forms O-Na+ salt and water

Question 16

Reaction of amino acid with hydrochloric acid?

Answer 16

Ammonium salt + Cl-

Question 17

Reaction of Amino acid + alcohol

Answer 17

Forms an ester and water

Question 18

What is optical isomerism?

Answer 18

It is a form of stereoisomerism and has a chiral carbon atom. They are non-super imposable mirror images.

Question 19

What is a chiral carbon atom?

Answer 19

A carbon atom that has four different groups attached to it.

Question 20

What is another word for optical isomers/mirror image?

Answer 20

Enantiomers

Question 21

How do you know how many optical isomers a structure has?

Answer 21

2 to the power of the number of chiral carbons.

Question 22

What are addition polymers?

Answer 22

Double bonds in Alkenes break to form a long chain of monomers.

Question 23

What are condensation polymers + examples?

Answer 23

Usually involves two different types of monomers and each monomer has two functional groups. These groups link to form a polymer chain and each link releases a molecule of water. Examples include Polyamides and polyesters

Question 24

How to form Polyamides?

Answer 24

Reaction between a dicarboxylic acid and a diamine.

Question 25

How do you form polyesters?

Answer 25

Reaction of dicarboxylic acids with diols.

Question 26

Products and reagents for hydrolysis of Polyamides?

Answer 26

1) add water and acid. Forms a dicarboxylic acid and a diammonium salt.

Question 27

Products and reagents for hydrolysis of polyesters?

Answer 27

Reaction with bases eg NaOH. Forms a dicarboxylate salt and a diol.

Question 28

Steps to find monomer?

Answer 28

1) remove the bond in the middle of the amide and ester links.
2) add -OH groups onto the C=O group and the oxygen in polyesters. For Polyamides, add Hydrogens on the NH group.
3) for polyesters, add Hydrogens on the Oxygens to make OH groups ans add OH on any terminal carbon atoms.

Question 29

What is a condensation polymer?

Answer 29

When monomers bond together to form a chain and another small molecule