solomons and fryhle

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solomons and fryhle
Organic chemistry I
Zdeněk Friedl
Chapter 11
Hydroxy derivatives
Solomons & Fryhle: Organic
Chemistry 8th Ed., Wiley 2004
Hydroxy derivatives
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structure of hydroxy compounds and physical properties
reaction scheme of alcohols
nucleophilic substitution reactions SN1 and SN2
intramolecular nucleophilic substitution SNi
acid catalyzed E1 and E2 dehydration of alcohols
oxidation of alcohols
reaction scheme of phenols
electrophilic substitution reaction SEAr on phenols
oxidation of phenols
reaction scheme of naphthols, Bucherer reaction
2
The electrostatic potential map of methanol
3
Hydrogen bonding between molecules of methanol
4
Physical properties of alcohols
5
The reaction scheme of alcohols
SN(H+) and E reactions
δ+
R CH C
SN (2,1)
δ−
O
H
Hβ
E (2,1)
δ+
H+
-
B
6
Alcohols as the O acids
7
pKa
Definition of acidity constants pKa
H-A + H2O D
A- + H3O+
Keq = [A-] [H3O+] / [HA] [H2O]
Ka = Keq [H2O] = [A-] [H3O+] / [HA]
pKa = - log Ka = log [HA] / [A-] - log [H3O+]
pKa = log [HA] / [A-] + pH
8
pKa
Derivation of pKa constant for H2O
H2O + H2O D
OH- + H3O+
Keq = [OH-] [H3O+] / [H2O]2
Ka = Keq [H2O] = [OH-] [H3O+] / [H2O]
Ka = 1.0 x 10-14 / 55.6 = 1.80 x 10-16
pKa = 15.74
9
pKa
Relative strength of selected acids
and their conjugate bases
10
SN2
A mechanism for the reaction of alcohols with Br1° alcohols and methanol
without acid catalysis the SN2 reaction NOT PROCEEDS
11
SN2
A mechanism for the reaction
of alcohols with HNu
1° alcohols and methanol
12
SN2
A mechanism for the reaction of alcohols with HX
HI > HBr > HCl
(HF unreactive)
reaction of HCl with methanol, 1° and 2° alcohols needs catalysis of Lewis acid
13
SN2
An intermolecular SN reaction of 2° and 3° alcohols
a INVERSION of configuration
14
SNi
An intramolecular SN reaction of 2° and 3° alcohols
a RETENTION of configuration
Cl
CH3CH2
H
S O
H C O
Cl
H3C
(R) - SO2
- HCl
benzene
CH3CH2
H C O
H3C
S O
Cl
CH3CH2
H C Cl
H3C
(R) -
15
SN1
A mechanism for the reaction of alcohols with HX
3°, allyl and benzyl alcohols
16
SN1
Stereochemistry of a reaction of alcohols with HX
chiral alcohols a RACEMIZATION of product
(R) or (S)-3-methyl-3-hexanol gives a racemic form of
(±)-3-brom-3-methylhexane
17
SN2 vs. E2
Intermolecular dehydration of alcohols
18
E2
Acid-catalyzed dehydration of 1° alcohols
19
E1
Acid-catalyzed dehydration of 2° and 3° alcohols
20
E1
The relative Gibbs energy of activation for the
formation of 1°, 2° and 3° carbocations
21
E1/RN
Rearrangements in dehydration of 2° alcohols
22
E1/RN
Rearrangements in dehydration of 2° alcohols
ZAITSEV’S rule
23
Oxidation of 1° alcohols
NONSELECTIVE oxidation to aldehydes and carboxylic acids
24
Oxidation of 1° alcohols
SELECTIVE oxidation to aldehydes
25
Oxidation of 2° alcohols to ketones
26
Oxidation of 3° alcohols
27
Summary of synthetic reactions of alcohols
28
The reaction scheme of phenols
X
SNAr
δ
δ+
H
−
O
δ+
B-
SEAr
29
The electrostatic potential map of phenol
30
pKa
Relative acidity of alcohols and phenols
31
pKa
pKa constants of substituted phenols
32
SNAr
Cleavage of alkyl aryl ethers
The SNAr reaction does not occur
33
SEAr
Alkylation of phenols:
The Lewis acids as AlCl3 cannot be used
R OH + BF 3
R [HO-BF 3]
OH
OH
+ R [HO-BF 3]
R
34
RE
Alkylation (allylation) of phenols
CLAISEN rearrangement
35
RE
Acylation of phenols
FRIES rearrangement
36
SEAr
Bromination of phenols
37
SEAr
Nitration of phenols
38
SEAr
Sulfonation of phenols
39
SEAr
Formylation of phenols
REIMER-TIEMANN reaction
O
O
O
\
O
_
CCl2
|CCl2
H
OH
CHCl2
CH=O
H2O
H
40
SEAr
Carboxylation of phenols
KOLBE reaction
41
Oxidation of phenols
electron transfer in nature
42
The defense reactions of bugs
The Bombardier beetle’s noxious spray
OH
O
+ H2O2
OH
enzyme
+ 2 H2O (100 °C)
O
43
The reaction scheme of 2-naphthol
(NH3)
SN
δ−
O
OH
δ+
SEAr
44
SN
Nucleophilic 1,4-addition/substitution
BUCHERER reaction
OH
O
OH
NH4HSO3
H
NH
- NH4HSO3
NH3
H
SO3 NH4
NH2
SO3 NH4
45
Summary of phenol synthetic reactions
46

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