Chapter 27 - Amines, amino acids

Question 1

Define amines

Answer 1

They are derived from NH3 (ammonia) in which one or more of the hydrogen atoms in ammonia are replaced by a carbon chain or ring.

Question 2

Define an aliphatic amine

Answer 2

Nitrogen is attached to at least 1 straight chain or branched alkyl chain.

Question 3

Define aromatic amine

Answer 3

Nitrogen is attached to an aromatic ring. (usually nitrobenzene)

Question 4

What is a primary amine

Answer 4

NH2R.

Remember to draw the lone pair of electrons above the N

Question 5

What is a secondary amine

Answer 5

NHR’R’’.
It depends on the number of R groups attached to the N.
Remember to draw the lone pair of electrons on the N.

Question 6

Examples of amines

Answer 6

Serotonin (acts as a neurotransmitter, controlling appetite, sleep, memory, learning and temperature.)
Pseudoephedrine (an active ingredient in decongestion medicines)

Question 7

How do you name amines

Answer 7

Add an ‘amine’ to the end.
Secondary and tertiary amines- add ‘di’ or ‘try’ as a prefix.
When there are 2 or more groups attached to the nitrogen atom, name it as an N- substituted derivative of the larger group.

Question 8

Smell of amines

Answer 8

It smells like rotting fish

Question 9

Reactions of amines as bases

Answer 9

Due to the lone pair on the nitrogen, they can accept a proton, creating a dative covalent bond.
They can react with acids to give salts.
If it is a NH2, it becomes :
NH3+ X-.

Question 10

Preparation of aliphatic amines

Answer 10

The lone pair of electrons on Nitrogen allows ammonia to act as a nucleophile.

Question 11

How can you create a primary amine

Answer 11

1. Haloalkane + ammonia -> salt.
   Add excess ammonia. (is a nucleophilic substitution)
2. Salt + NaOH -> primary amine + water + Na-X.
   Ethanol can be used as a solvent to prevent substitution of the haloalkane and production of alcohol.

Question 12

How can you create a secondary amine

Answer 12

1. Primary amine + haloalkane -> salt.

2. Salt + NaOH -> Na-X + Secondary amine + water.

Question 13

Preparation of aromatic amines

Answer 13

Made by the reduction of nitrobenzene.
Nitrobenzene + 6[H+] -> Phenylamine + 2H20.
above the arrow: 1. Sn/ Concentrated HCl.
2. excess NaOH.

Question 14

what is an amino acid

Answer 14

It contains both amine and carboxylic acid functional groups.

Question 15

Amino acid + acids

Answer 15

Amino acid + acids -> salt + acid ion.

this is a reaction of the amine group

Question 16

How many amino acids are there?

Answer 16

20.

Question 17

Amino acid + alkalis

Answer 17

Amino acid + alkalis -> salt + water

Question 18

Amino acid + alcohols

Answer 18

Amino acid + alcohols -> esters

Question 19

Esterification

Answer 19

excess ethanol

and a small amount of sulphuric acid.

Question 20

Define a zwitterion

Answer 20

It has no charge, because the H+ ion from the COOH group can move to the NH2 group and form a + and a - charge.

Question 21

Define the isoelectric point

Answer 21

It is the pH at which the zwitterion is formed, and each amino acid has its own unique isolectric point.
If you have a pH above the isolelectric point, then you form a COO- ion.

Question 22

Define an optical isomer

Answer 22

A chiral carbon with 4 different groups, making it a non-superimposable mirror image.

Question 23

What is glycine

Answer 23

It is the most simplest amino acid.

Question 24

Define a chiral centre

Answer 24

a Carbon atom that is attached to 4 different groups or atoms.

Question 25

How do you name amino acids

Answer 25

The COOH group is always more prioritised, so the Carbon attached to the COOH group is carbon 2.

Question 26

Define bi-functional

Answer 26

Can behave as an acid or an alkali as it has both functional groups.

Question 27

Define the racemix mixture

Answer 27

They have equal amounts of left and right handed enantiomers of a chiral molecule.

Question 28

Define a condensation polymer

Answer 28

Joining of monomers with the loss of a small molecule (usually water or HCl)

Question 29

What are the 2 ways in which a polyester can be made?

Answer 29

1. 1 monomer containing 2 functional groups ( so It should have OH on one side and COOH on the other.) 2. 2 monomers that have COOH on both sides or OH on both sides.

Question 30

What is a monomer that has 2 OH groups

Answer 30

a diol

Question 31

What is a monomer that has 2 COOH groups

Answer 31

A dicarboxylic acid

Question 32

Examples of a polyester made from 1 monomer

Answer 32

``` called PET (Polyethylene terephthalate) it is made using benzene-1,4 di carboxylic acid and ethane-1,2 diol. ```

Question 33

How are polyamides formed

Answer 33

By a condensation reaction using a monomer that has both a carboxylic acid functional group (or acyl chloride) and an amine group functional group. Or by 2 monomers which have 2 COOH functional groups and another which has 2 NH2 functional groups.

Question 34

What is an ester functional group

Answer 34

COO

Question 35

What is an amide functional group

Answer 35

COHN

Question 36

What is a monomer with 2 amine groups called

Answer 36

Diamine

Question 37

What is nylon made from?

Answer 37

Using hexanedioic acid and 1,6 diaminohexane or hexanedioyl chloride and 1,6 diaminohexane

Question 38

How do you name nylons

Answer 38

The first number is the number of Carbons in the amino group, and then the Carboxylic acid group one next.

Question 39

Acid hydrolysis of a polyester

Answer 39

``` Use H2SO4 (hot aqueous)/ H20 Products: Just the monomers ```

Question 40

Alkali hydrolysis of a polyester

Answer 40

Use NaOH/H2O | Products: alcohol and carboxylic-salt.

Question 41

Acid hydrolysis of a polyamide

Answer 41

Use H20 /H+ | Products: NH3+ on the amines and a carboxylic acids.

Question 42

Alkali hydrolysis of a polyamide

Answer 42

Use NaOH/ H2O | Products: COO- Na+ and NH2 amines.

Question 43

Characteristics of an addition polymer

Answer 43

Contains a C=C bond in the monomer | Contains a backbone of a continuous chain

Question 44

Characteristics of a condensation polymer

Answer 44

2 monomers with 2 functional groups (on either sides) 1 monomer with 2 different functional groups Polymer has ester/ amide linkages.

Question 45

C-N bond

Answer 45

It is polar. | The nitrogen is very electronegative, so it's quite easy to break this C-N bond as it's a weaker bond.

Question 46

Ammonia gas + HCl gas

Answer 46

It creates white smoke. | And NH4+Cl-

Question 47

Outline how an addition polymer is formed?

Answer 47

The pi-bond breaks and many molecules join together.

Question 48

Explain why xyz is considered to be a "degradable polymer"?

Answer 48

Because the C=O or the C-N bond can break and it is hydrolysed so that the polymer can be broken into its monomers.

Question 49

WHENEVER THERE IS ANYTHING ABOUT GREATER MELTING POINT?

Answer 49

ALWAYS INTERMOLECULAR FORCES!! | IS THERE ANY HYDROGEN BONDING? ANY LONDON FORCES? PERMANENT DIPOLE?!

Question 50

Why are secondary amines stronger bases than primary amines?

Answer 50

Because they have 2 alkyl groups that better stabilize the acid than primary amines, and so making it more basic.

Question 51

How do amines behave?

Answer 51

They behave as weak bases.

Question 52

State 2 disadvantages of synthesising something that makes a mixture of optical isomers? Then 2 methods that are used to synthesis the only wanted optical isomer

Answer 52

One stereoisomer may have adverse side effects, and the cost of separating the stereoisomers can be quite high. Methods: You have use natural chiral molecules or use enzymes or bacteria.

Question 53

Diazonium ion

Answer 53

A benzene ring where there is a N=-N attached to one Carbon atom.

Question 54

How can a polymer be broken down.

Answer 54

Either by hydrolysis or photodegradable