Acid anhydrides and aspirin 2

1.

Acid anhydrides and Aspirin

2.

Learning Objectives
• know and be able to use the mechanism of
acylation reactions
• understand the role of acylation in the manufacture
of aspirin

3.

Expected Outcomes
• Draw and outline reaction mechanisms for various
acylation reactions
• Differentiate alkylation and acylation and identify
their uses
• Explain the role of acylation in the manufacture of
aspirin and write pertinent equation for this

4.

Keywords
Acid anhydrides
Nucleophilic substitution
Acylation
Alkylation
Acyl group
Nucleophilic attack
Nucleophile
Leaving group
Deprotonation

5.

Review Task – Silent Reading Activity (12 mins)
• Read on pp. 386-387 of your coursebook.
• Answer Check-up question nos. 3 and 4.
• Be ready to discuss your answers in class.

6.

Be able to use the mechanism of acylation reactions
Reactions of Acid Anhydrides

7.

Be able to use the mechanism of acylation reactions

8.

Be able to use the mechanism of acylation reactions

9.

PAIR WORK ACTIVITY
Task: Show the complete mechanism for the following reactions.
1. Ethanoic methanoic anhydride + water
2. Ethanoic methanoic anhydride + ethanol

10.

Be able to use the mechanism of acylation reactions
I can use the mechanism of acylation in various reactions of acid
anhydrides.

11.

understand the role of acylation in the manufacture of aspirin
Synthesis of Aspirin (acetylsalicylic acid) is a medication
used to reduce pain, fever, or inflammation.

12.

understand the role of acylation in the manufacture of aspirin
Using acid anhydride
Using acid chloride
The use of ethanoic anhydride is the preferred

13. Comparing Acyl Chlorides and Anhydrides

In organic synthesis reactions, the use of acid anhydride is
favoured over the corresponding acid chloride for several reasons:
acid chlorides (e.g. ethanoyl chloride)
• difficult to handle as they react very readily with
water so need to be used in water-free conditions
• react to produce corrosive HCl
acid anhydrides (e.g. ethanoic anhydride)
• cheaper to produce
• not as moisture sensitive
• less corrosive
• produce carboxylic acids, which are safer than HCl

14.

Alkylation is known as the addition or substitution of an alkyl group
to an aromatic ring.

15.

Acylation is a reaction in which an acyl group is added to a
molecule

16.

17.

understand the role of acylation in the manufacture of aspirin
I understand the role of acylation in the manufacture of aspirin

18.

Reflection
• What has been learned
• What remained unclear
• What is necessary to work on