1. SCUM!
Ca salts are insoluble and form an unsightly scum
Explain.

2. NO SCUM!
Detergents, however have sulphonic acuds which form soluble salts so that no scum is formed
Explain.

3. Acylation

4. Predict the reaction

5. A new molecule is in town!
Describe it.
What is it likely to be made from?
Suggest a name for a two-carbon molecule.

6. Acyl chlorides vs COOH acids
Carbonyl group is reactive
Chlorine is a very good leaving group!
Which molecule is better and how?

7. Acyl chlorides vs COOH acids
Carbonyl group is reactive
Chlorine is a very good leaving group!
What would form? Does the intermediate determine reactivity?

8. Acyl chlorides derive from carboxylic acids+
POCl3 +
PCl5 +
HCl

9. Acyl chlorides derive from carboxylic acids+
HCl +
SOCl2 +
SO2

10. + Hydrolysis of ethanoyl chloride Try the mechanism! Observations?
It’s so reactive, it reacts rapidly with cold water!

11. + ethanoyl chloride & methanol Try the mechanism! Observations?
The acyl chloride reacts with alcohol without heating.

12. NH3 + ethanoyl chloride & concentrated ammonia Try the mechanism!
Observations?
NH3 +
The acyl chloride reacts with conc. ammonia without heating.

13. ethanoyl chloride & propylamine
Try the mechanism!
ethanoyl chloride & propylamine +

14. Acid anhydrides
This alternative synthetic intermediate is also used in acylation reactions. Suggest why.
Good leaving group

15. Acid anhydrides NaCl + +
They are made when RCOCl are reacted with RCOONa. Complete the equation. +
ONa +
NaCl

16. Acyl chlorides vs acid anhydrides
Why are acid anhydrides used on a large scale as an acylating agent?

17. Acyl chlorides vs acid anhydrides
Cheap Less corrosive Less vulnerable to hydrolysis Less dangerous

18. e.g. In synthesis of aspirin
Acid anhydrides are better as they are cheaper, less corrosive and only produce ethanoic acid rather than HCl. But acyl chlorides are more reactive than acid anhydrides.
What has happened? Why is an acyl chloride not used? What acyl chloride would be used?

19. Acylation reactions
RCOCl + H2O (RCO)2O + H2O RCOCl + CH3OH (RCO)2O + CH3OH RCOCl + NH3 (RCO)2O + NH3 RCOCl + CH3NH2 (RCO)2O + CH3NH2

20. Acylation reactions
RCOCl + H2O (RCO)2O + H2O RCOCl + CH3OH (RCO)2O + CH3OH RCOCl + NH3 (RCO)2O + NH3 RCOCl + CH3NH2 (RCO)2O + CH3NH2
RCOCl + H2O
(RCO)2O + H2O
RCOCl + CH3OH
(RCO)2O + CH3OH
RCOCl + NH3
(RCO)2O + NH3
RCOCl + CH3NH2
(RCO)2O + CH3NH2

21. Homework
Biodiesel research and power-point for next week’s lesson.