PL - Amines and amides

Question 1

What are amines?

Answer 1

Organic derivatives of ammonia.

Question 2

How is a primary amine formed?

Answer 2

If one of the hydrogens in ammonia (NH3) is replaced with an organic group, R.

Question 3

How do small amines smell?

Answer 3

Similar to ammonia, with a slightly ‘fishy’ twist.

Question 4

How do larger amines smell?

Answer 4

Very ‘fishy’.

Question 5

Are amines acidic of basic?

Answer 5

Basic.

Question 6

How can you test for amines?

Answer 6

See whether it turns a piece of damp red litmus paper blue (as amines are basic).

You can confirm that the unknown compound is an amine by reacting it with a small amount of acyl chloride - if it’s and amine, white fumes of HCL gas will be given off.

Question 7

How do you name a primary amine?

Answer 7

Find and name the longest alkane chain attached to the amine group, take off the final ‘e’ and add ‘-amine’ to the end.

If the carbon chain is more than 2 carbons long, you should include a number to show which carbon the amine group is attached to. Number the carbon chain so that the amine group has the smallest possible number.

Then use the suffix ‘-amine’ or prefix ‘amino-‘.

Question 8

What is it called if the molecule has 2 amine groups?

Answer 8

A diamine.

Question 9

What is a diamine?

Answer 9

A molecule that has 2 amine groups.

Question 10

How do you name diamine?

Answer 10

In the same way as primary amines except you use the suffix ‘-diamine’, and keep the final ‘e’ of the alkane stem.

Question 11

Why is an amine a base?

Answer 11

Because it has a lone pair of electrons.

They act as bases because they accept protons, forming a cation (a positively charged ion).

Question 12

Where’s the lone pair of electrons in an amine?

Answer 12

On the nitrogen atoms that can form a dative covalent (coordinate) bond with an H+ ion.

Question 13

How can you neutralise an amine?

Answer 13

By reacting it with an acid to make an ammonium salt.

Question 14

What is the general equation for the neutralisation of an amine?

Answer 14

RNH2 + HX –> RNH3+X-

Question 15

What are amides?

Answer 15

Carboxylic acid derivatives.

Question 16

Why do amides behave differently from amines?

Answer 16

Because the carbonyl group in amides pulls electrons away from the rest of the -CONH2 group.

Question 17

What are the different types of amides?

Answer 17

Primary and secondary.

Question 18

Whether an amide is a primary or secondary amide depends on what?

Answer 18

How many carbon atoms the nitrogen is bonded to.

Question 19

How many carbon atoms is the N bonded to in a primary amide?

Answer 19

1

Question 20

How many carbon atoms is the N bonded to in a secondary amide?

Answer 20

2

Question 21

How do you name primary amides?

Answer 21

Use the stem of the carbon chain, followed by -amide.

Question 22

How do you name secondary amides?

Answer 22

Use the stem of the carbon chain, followed by -amide.

Also, use the prefix N-alkyl- to describe the alkyl chain that is attached directly to the nitrogen atom.
E.g. N-ethylpropanamide.

Question 23

Under what conditions can amides be hydrolysed?

Answer 23

Acidic or basic.

Question 24

How can you hydrolyse an amide?

Answer 24

• Heat it with a dilute acid to get a carboxylic acid and an ammonium salt.

OR…

• Heat it with a dilute alkali to get a carboxylate ion and ammonia gas given off.

Question 25

What will heating a secondary amide with dilute acid produce?

Answer 25

A carboxylic acid and the salt of a primary amine.

Question 26

What will heating a secondary amide with dilute alkali produce?

Answer 26

A salt of the carboxylic and an amine.

Question 27

What will heating a primary amide with dilute acid produce?

Answer 27

A carboxylic acid and an ammonium salt.

Question 28

What will heating a primary amide with dilute alkali produce?

Answer 28

A carboxylate ion and ammonia gas.