Acylation

Question 1

What is acylation?

Answer 1

the process by which an acyl group is introduced to another molecule

R-CO( )

Question 2

What are acid derivatives?

Answer 2

• all have the acyl group as part of their structure
• two important derivatives are:
  
  • acid chlorides
  • acid anhydrides
• general formula RCOZ
  
  • Z can be a variety groups

Question 3

What is ethanoyl?

Answer 3

if the R group is CH3, the group is called ethanoyl

Question 4

How does acyl compounds react?

Answer 4

• carbonyl group is polarised
• attack by nucleophiles at the partially positive carbon
• nucleophile replaces the Z and therefore acquires an acyl group
• the nucleophile is acylated

Question 5

What are the factors that affect the reaction?

Answer 5

1. magnitude of the partially positive charge on the carbonyl atom, which in turn depends on the electron-releasing or attracting power of Z
2. How easily Z is lost
3. how good the nucleophile is

Question 6

How are the factors one and two linked?

Answer 6

• groups which strongly attract electrons tend to form stable negative ions
• these are good leaving groups

Question 7

what is an acid anyhdride? draw it

Answer 7

Question 8

What are the properties of the Z groups of acyl chlorides and acid anhydrides?

Answer 8

they withdraw electrons from the carbonyl carbon

this makes the carbon more positve

this makes these compounds more reactive towards nucleophiles

they are good acylating agents

chlorides more reactive than anhydrides