1. Aldehyde & Ketone

2. Nucleophilic Addition to the Carbonyl Group
Oxygen Nucleophiles
Sulfur Nucleophiles
Carbon Nucleophiles
Nitrogen Nucleophiles

3. Reactions at the -Carbon of Aldehyde & Ketone

4. Reactions at the -Carbon of Carbonyl Compounds
Acidity of the -hydrogens
Keto-Enol tautomerization
Applications

5. Acidity of the -hydrogens

6. pKa
C2H6 50
C2H4 44
NH3 34
C2H2 25
CH3COCH3 20
C2H5OH
15.9
H2O
15.74
Ph-OH 10
H2CO3
6.5

7. Keto-Enol Tautomerization
Which makes a greater contribution to the hybrid?
Keto
Enol

8. A. Interconversion：

9. Monocarbonyl compounds
B. Keto-enol tautomers
in equilibrium
[enol] K＝
[keto]
Monocarbonyl compounds
(100%) (extremely small)
(99%) (1.5×10-4%)
(98.8%) (1.2%)

10. -dicarbonyl compounds
24%
76%
Phenol
K  1014

11. C. Detection:
+ FeCl3
Purple or blue

12. D. Formation of enolate:
Which “Base”?

14. enolate

15. Thermodynamic enolate
E. Regioselective Formation of Enolate Anions ? ?
Kinetic enolate
Thermodynamic enolate
Generally:
1. Low temperature gives the kinetic enolate.
2. High temperature, relatively weak base in a protic solvent gives the thermodynamic enolate.

16. 2. In acid condition, the thermodynamic enol is formed predominantly.
Two special examples:
1. The kinetically favored enolate can be formed cleanly through the use of diisopropylamide (LDA).
2. In acid condition, the thermodynamic enol is formed predominantly.
LDA
enol
enolate

17. F. Racemization:

18. Application alkoxide anions Nucleophilic center Nucleophilic center
carbanion
Ambident nucleophile

19. React as an alkoxide anions
trapped

20. React as a carbanion

21. React as a carbanion 1: Halogenation
Haloform reaction

22. iodoform reaction

23. React as a carbanion 2: Alkylation
side reaction:

24. solution:

25. React as a carbanion 3: Aldol Reaction
Reversible

26. easy
difficult

27. How does it work?
catalyst
Soxhlet Extractor
acetone

29. Crossed Aldol Reaction

30. Practical Crossed Aldol Reaction

31. React as a carbanion 4:

33. glycolysis