1. Acyl Insertions (J&F Ch. 18)
Chemistry 125: Lecture 72 April 22, 2011
Acyl Insertions (J&F Ch. 18)
-H Reactivity (J&F Ch. 19)
Condensations (J&F Ch. 19)
This
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2. C O Y X R Acyl Insertions O R NH R CH2 OH Baeyer-Villiger Beckmann
ketone ester NH R
Beckmann
ketone amide
CH2 OH
Arndt-Eistert
lengthen chain

3. Baeyer-Villiger Reaction - 1900 (insert O) (e.g. J&F pp. 907-909)

4. Beckmann Rearrangement – 1886 (insert N) (e.g. J&F pp. 909-911)

5. Arndt-Eistert Homologation – 1935 (insert C) (e.g. J&F pp. 915-917)

6.  Acidity (J&F Tables 19.1 (p. 933), 19.2 (p. 943), 19.3 (p. 958))
pKa
pKa 17 9 19 11 24
weaker than
H-OH
stronger than
H-OH
except 13 24 18 18 25 11

7. LDA hindered strong base (pKa = 36) (J&F p. 944)
Lithium
Diisopropyl
Amide
K ~ 1011
pKa ~ 25
complete formation
even of amide enolate not just a little at equilibrium
(slow attack on C=O, none on enolate)

8. Nucleophilic a-Carbon

9. Acid & Base  H/D Exchange via enol and enolate (e.g. J&F Sec. 19.2a)
-OD
D-OD

10. Racemization via enol and enolate (e.g. J&F Sec. 19.3)H
enol
enolate A B H
both planar

11. -Halogenation Ketones / Aldehydes (e.g. J&F Sec. 19.4a)
I-I I
enol
enolate

12. -Halogenation Ketones / Aldehydes (e.g. J&F Sec. 19.4a)
Diiodomethyl
Iodomethyl
pKa ~14
R-COO- + HCI3
Andel Früh
Iodoform is a bright yellow solid + I
R-COOH + -CI3 I I
I-I I
Thus the
Iodoform Test
for methyl ketones
enol + I I
enolate
HO- I
-OH I I

13. -Halogenation Carboxylic AcidsCl O
Cl- O Cl O- S O Cl O-
SO2 Cl
Cl- O S O Cl
X = Cl ; Y = Cl + stable SO2
Hell-Volhard-Zelinsky ~ (e.g. J&F Sec.19.4b)
PBr3

14. -Alkylation Ketones / Aldehydes (e.g. J&F Sec.19.5a)

15. End of Lecture 72 April 22, 2011
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