6.2.1 Amines

Question 1

What can amines be classified as?

Answer 1

Primary, secondary or tertiary

Question 2

What is the identity of an amine classified by?

Answer 2

The number of carbon alkyl (carbon chain) or aryl (benzene ring) attached to an N atom.

Question 3

What are the steps for naming primary amines where the NH2 is at the end of the carbon chain?

Answer 3

1. Name carbon chain e.g. methyl
2. Add the suffix amine

E.g. methylamine

Question 4

What are the steps for naming primary amines where the NH2 is not at carbon 1?

Answer 4

1. Name the carbon chain
2. Add the prefix of amino with the carbon number it is attached to

E.g. 2-aminopropane

Question 5

What are the steps for naming secondary and tertiary amines if the groups attached to the N are the same?

Answer 5

1. Name carbon chain
2. Put number before it e.g. di, tri etc.
3. Add amine to the end
4. Add an N at the front for every group attached to the nitrogen

E.g. N,N dimethylamine

Question 6

What are the steps for naming secondary and tertiary amines if the groups attached to the N are different?

Answer 6

1. Workout the name of the carbon groups attached to the nitrogen
2. Put them in alphabetical order
3. If 2 groups are attached, an N goes in front of the first group only. (N-methylpropylamine)

If 3 groups are attached, an N goes infront of the first 2 groups (N,ethyl, N,methyl - propylamine)

4. Add amine at the end

Question 7

Can amines act as bases?

Answer 7

YES

Question 8

How can amines act as bases?

Answer 8

Amines behave as bases in chemical reactions

The lone pair of electrons on the nitrogen accepts a proton

A dative covalent bond is formed

They form an ammonium ion

Question 9

What is formed when an amine acts as a base?

Answer 9

An ammonium ion

Question 10

What can amines neutralise?

Answer 10

Acids

Question 11

What is formed when an amine neutralises an acid?

Answer 11

A salt

Question 12

Ethylammoniumchloride

Answer 12

CH3CH2NH3+Cl-

Question 13

What does the strength of an amine as a base depend on?

Answer 13

Depends on how available the nitrogen’s lone pairs of electrons

A lone pair of electrons are more available if its electron density is higher

The higher the density, the more available the lone pair, the stronger the base

Question 14

Why is an aromatic amine the weakest amine base?

Answer 14

Benzene draws electrons into the ring, the lone pair of electrons on the nitrogen partially delocalise

The availability of the lone pair decreases so the lone pair of electrons are less available

Question 14

What is the weakest amine base?

Answer 14

Aromatic amine

Question 15

What is a medium strength amine base?

Answer 15

Ammonia

Question 16

Why is ammonia a medium strength amine base?

Answer 16

There is no aromatic ring or alkyl group so the lone pair is available

Question 17

What is the strongest amine base?

Answer 17

An aliphatic amine

Question 18

Why is an aliphatic amine the strongest amine base?

Answer 18

The alkyl group pushes electrons towards the nitrogen, so the lone pair on the nitrogen is more available

Question 19

How many steps are there when forming a primary amine?

Answer 19

2

Question 20

What are the two steps to form a primary amine?

Answer 20

1. Ammonia has a lone pair of electrons on the nitrogen atom which allows it to act as a nucleophile in a reaction with a haloalkane. PRODUCT OF THIS REACTION IS AN AMMONIUM SALT
2. Aqueous alkali (NaOH) is added to generate the amine from the salt

Question 21

What are the conditions needed to produce a primary amine?

Answer 21

Excess NH3

Ethanol as a solvent to prevent substitution of the haloalkane by water to make an alcohol (ammonia dissolved in solvent (ethanol) = ethanoic ammonia)

Question 22

How many steps are there to produce a secondary amine?

Answer 22

2

Question 23

What are the 2 steps in order to produce a secondary amine?

Answer 23

1. Primary amine + haloalkane —-> ammonium salt
2. Ammonium salt + NaOH —> secondary amine

Question 24

How many steps are there to produce a tertiary amine?

Answer 24

1

Question 25

What is needed to make a tertiary amine?

Answer 25

The secondary amine can react with the haloalkane to make a tertiary amine

Question 26

How are aromatic amines formed?

Answer 26

Phenylamine if made by the reduction of nitrobenzene

Question 27

What are the conditions for the reduction of nitrobenzene?

Answer 27

Concentrated HCl, tin Reflux