1. 12.6 Aldol Reaction and Aldol Condensation
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12.6 Aldol Reaction and Aldol Condensation
General reaction:
b-hydroxycarbonyl 2 3 1
Aldol reaction 2
Aldol condensation
a,b-unsaturateed carbonyl

2. Mechanism of Aldol Reaction
E-enolate
Z-enolate
Aldol reaction can be reversible (retro-Aldol reaction).

3. Examples of Aldol Reaction/Condensation
-H2O

4. Potential Problem of Aldol Reaction
Mixed aldol reaction:
Desired product
To avoid the formation of by-products:
Add slowly

5. Use Selected Aldehydes for Aldol Reaction
Aldehydes that have no a-hydrogens:
furfural
formaldehyde
benzaldehyde
pivaldehyde, trimethylacetaldehyde
2,2-dimethylpropanal

6. Intramolecular Aldol Reaction
Formation of 5- or 6-membered rings.
a-H
6-membered
8-membered
Not formed

7. Intramolecular Aldol Reaction
Formation of 5- or 6-membered rings.
a-H
5-membered
7-membered
Not formed

8. Intramolecular Aldol Reaction
Formation of 5- or 6-membered rings.
a-H
5-membered
5-membered
7-membered
Not formed

9. Robinson Annulation: Michael Addition Followed by Aldol Condensation
H+, heat
Michael addition
Aldol reaction

10. Learning Check
1. What could be the product for the following reaction?

11. Learning Check
2. What could be the product for the following reaction?
3. What could be the product for the following reaction?

12. Learning Check
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4. What could be the product for the following reaction? 2 2