Amides

Question 1

Draw the structure of the amide group

Answer 1

See notes page 15

Question 2

Describe the nomenclature of amides

Answer 2

1️⃣ use parent acid name - replace ‘-oic acid’ with ‘-amide’
2️⃣ if branched - ‘-CONH2’ group counts as number 1 carbon atom
3️⃣ if alkyl substituents on nitrogen atom - name is preceded by ‘N- (alkyl)’ eg N-methylbenzamide

Question 3

Describe the physical properties of amides

Answer 3

⭕️ Methanamide = liquid but rest are white solids

⭕️ high bp - hydrogen bonded dimers forming

Question 4

Draw the H bonded dimer of amides

Answer 4

See notes pg 17

Question 5

What are the two methods of preparing an amide

Answer 5

1. React carboxylic acids with ammonia

2. React ammonia/amines with acyl chlorides

Question 6

Write the equation of acid hydrolysis of ethanamide

Answer 6

Carboxylic acid and ammonium salt of dilute acid produced

See notes page 18

Question 7

Write the equation for base hydrolysis of ethanamide

Answer 7

See notes page 18

Salt of carboxylic acid and ammonia gas produced

Question 8

How do you test if something is an amide

Answer 8

• add NaOH (base hydrolysis) and heat
• if ammonia gas produced then it’s an amide
• test for ammonia gas: conc HCl ➡️ white smoke observed

Question 9

What is the definition of dehydration of amides

Answer 9

A reaction which involves the elimination of water from the amide, forming a nitrile

Question 10

Write the equation for the dehydration of ethanamide

Answer 10

See notes page 18

Question 11

Why are amides weak bases

Answer 11

1️⃣ lone pair on N delocalised w pi bond of C=O
2️⃣ makes lone pair more stable
3️⃣ electrons less easily donated to hydrogen atom