Amides

Question 1

What is the amide functional group?

Answer 1

R—C(double bond) O -CONH2

NH2

Question 2

How are they named?

Answer 2

They are names from the carboxylic acid e.g. methanoic acid —> methanamide

Question 3

Preparation of amides

Describe what happens and show the equation of the Dehydration of an ammonium salt of a carboxylic acid?

E.g. ammonium ethanoate

Answer 3

Heating an ammonium salt of a carboxylic acid

CH3C=O —> CH3C=O + H2O
\ O-NH4+ \ NH2
Ammonium Ethanamide
ethanoate

Question 4

Show the reaction and name the reactants and products of an acyl chloride with an amine e.g. ethylamine and ethanoyl chloride

Answer 4

An acyl chloride with an amine to form an N-substituted amide

CH3CH2NH2 + CH3COCl —> CH3CONHCH2CH3 + HCl

Take a H off the NH2 and the Cl off the acyl chloride and join the C and N

Look in notes

Question 5

Hydrolysis of amides

Acid hydrolysis

What is produced?
What is it reacted with?
Do the reaction if ethanamide for acid catalysed hydrolysis

Answer 5

Produces a carboxylic acid and the ammonium salt of the dilute acid

You need the amide, H2O and an acid e.g. HCl

CH3CONH2 + H2O + HCl —> CH3COOH + NH4Cl

Ethanamide + water + hydrochloric acid —> Ethanoic acid + Ammonium chloride

Question 6

Alkaline hydrolysis of amides

What are the reactants?
What are the products?
Do an eqn e.g. Ethanamide
What can it be a test for?

Answer 6

Reactants - Amide and Sodium hydroxide

Products - carboxylic acid and ammonia gas

CH3CONH2 + NaOH —> CH3COONa + NH3

Test for an amide, warm the solid organic product with sodium hydroxide solution, produces ammonia gas, test for ammonia gas by dipping a glass rod in concentrated HCl and you’ll get white smoke

Question 7

Dehydration of amides

How are amides dehydrated?

Answer 7

Distilling them over Phosphorus pentoxide (P2O5)

Question 8

What do dehydrated amides form

Answer 8

Nitriles C(triple bond)N

Question 9

Do the dehydration of propanamide

Answer 9

CH3CH2CONH2 —> CH3CH2C(triple-bond)N + H2O

Propanamide —> propanenitrile

Question 10

Are amides good or bad bases? And why?

Answer 10

Poor bases because of the delocalisation of the lone pair of electrons on the nitrogen atom with the Pi bind of the C=O makes the lone pair more stable - less easily donated to a hydrogen atom

Question 11

Give the following in order of decreasing basic strength 
1° amine 
3° Amine 
Ammonia 
Phenylamine 
Amide
2° amine

Answer 11

3° amine 
2° amine 
1° amine 
Ammonia 
Phenylamine 
Amide