Transcript Alcohols - MSU Denver

Alcohols
Nomenclature
Properties
Preparation
Reactions
Spectroscopy
Alcohol
Nomenclature
IUPAC
Common
Carbinol
Preparation
Reactions
 Reduction
of carbonyl compounds
 Hydration of Alkenes
 Grignard reactions
Reduction of Carbonyl
Compounds


Reduction of Aldehydes/ketones
Reduction of Carboxylic acids/Esters
Reduction of
Aldehydes/Ketones
Hydrogenation
H2
R C H Pt
O
RCH 2OH Primary ROH
H2
R C R'
Pt
O
H
R C R'
OH
Secondary ROH
Reduction of Aldehydes/Ketones
Hydride Reductions
LiAlH4
RCH
RCH 2OH Primary ROH
or
O
NaBH 4
R C R'
O
LiAlH4
or
NaBH 4
H
R C R'
OH
Secondary ROH
Reduction of Carboxylic
Acids and Esters
Lithium Aluminum Hydride
Reduction
R
C OH
LiAlH4
RCH 2OH + OH
-
O
R
C OR'
O
LiAlH4
RCH 2OH + R'OH
Hydration of
Alkenes
 Acid
catalyzed Hydration
 Oxymercuration-Demercuration
 Hydroboration-Oxidation
Acid-Catalyzed Hydration
of Alkenes
 Markovnikov
addition
 Formation of most stable carbocation
 Shifts/rearrangements possible
H H
R
C
C H
R' H
R
C
C
R''
H
+
H 2O
H
+
H 2O
R
H
H
C
C H
OH H
R
R'
H
C
C
OH H
R''
Hydration of Alkenes via
Oxymercuration/Demercuration
Markovnikov addition
 Typically no shifts/rearrangements
 Mercurinium ion involvement

H H
R
C C H
R' H
R
C C R''
Hg(OAc) 2
NaBH 4
H 2O
Hg(OAc) 2
H 2O
R
H
H
C
C H
OH H
NaBH 4
R
R'
H
C
C R''
OH H
Hydroboration-Oxidation
of Alkenes
 Anti-Markovnikov
addition
 No shifts/rearrangements
 Syn addition
H H
R
C C H
R' H
R
C C R''
(BH 3 )2
(BH 3 )2
-
OH
H 2O 2
-
OH
H 2O 2
R
R
H
H
C
C H
H
OH
R'
H
C
C R''
H
OH
Grignard Addition
Reactions



Addition to Aldehydes/Ketones
Addition to Esters
Addition to Epoxides
Grignard Additions to Aldehydes/Ketones
Formation of primary, secondary, and
tertiary alcohols
H C H
RMgX
O
R' C H
RMgX
O
R' C R"
O
RCH 2OH
Primary ROH
H
R' C R
Secondary ROH
OH
RMgX
R"
R' C R
OH
Tertiary ROH
Grignard Additions to Esters
Formation of secondary and
tertiary alcohols
H C OR + 2R'MgX
O
R' 2CHOH + ROH
Secondary ROH
R'
R" C OR + 2R'MgX
O
R" C OH + ROH
R'
Teriary ROH
Grignard Addition to
Epoxides
O
+ RMgX
RCH 2 CH 2 OH
Prima ry ROH
O
+ RMgX
R'
R'
R'
R
OH
C
C
H
H
R'
Seconda ry ROH
R'
R'
O
R'
R'
+ RMgX
R'
R
OH
C
C
R'
R' R'
Tert ia ry ROH
Typical Alcohol Reactions
 Salt
formation
 Dehydration
 Oxidation
 Alkyl halide
formation
 Ester formation
 Ether
synthesis
 Periodic acid
cleavage of glycols
 Haloform reaction of
methyl carbinols
 THP acetal formation
Conversion of
Alcohols to Salts
Reaction with Active Metals
ROH
Na
-
+
RO Na + H 2
Dehydration of Alcohols
E-1
H
H+
R C C OH
E-2
H
R C C OH2 +
H
H
H
R C C OH2 +
rds
H2 O
H
H
R C C+
H
+
H
H
R C C OH
POCl3
H
H
a dichlorophosphate
interm ediate
H
R C C+
H
R C C
H
1,2-shifts/rearrangem ents possible
H
R C C OPOCl2
H
R C C OPOCl2
R C C
H
H
N
Anti periplanar (coplanar) elim ination
No 1,2-shifts/rearrangements possible
Oxidation of Alcohols
Primary
RCH2OH
PCC
KMnO 4
or
K 2Cr 2O 7
²
Secondary R 2CHOH
Tertiary
R 3COH
PCC or
KMnO 4
or
K 2Cr 2O 7
²
PCC or
KMnO 4
²
RCHO
RCOOH
R
C R
O
no reaction
Alcohol Conversion to
Alkyl Halides
 Reaction
with Hydrogen halides
 Reaction with Thionyl chloride
 Reaction with Phosphorus
trihalides or pentahalides
Hydrogen Halide Conversion of
Alcohols to Alkyl Halides
RCH 2OH
HX
R 2CHOH HX
R 3COH
HX
RCH 2X
SN 2 predominantly
R 2CHX
SN 1 or SN 2
R 3CX
SN 1 predominantly
where HX = HI, HBr, or HCl
Conversion of Alcohols to Alkyl
Chlorides via Thionyl Chloride
C
OH
primary or
secondary
alcohol
SOCl
C
O
S
Cl
2
O
alkyl chlorosulfite
Cl
-
S N2
C
Cl
+ SO 2 + HCl
Conversion of Alcohols to Alkyl
Halides via Phosphorus Halides
H
C
OH
primary or
secondary
alcohol
PX 3
C
O
+
PX 2
protonated
alkyl dihalophosphite
X
-
S 2
N
C
X + HOPX 2
Ester Formation from Alcohols
R
C Cl
R'OH
C OR' + HCl
R
O
R
R'OH
C O C R
O
R
O
C OH
O
R
O
R'OH
H
+
R
C OR' + R
C OH
O
O
C OR' + H 2O
O
Periodic Acid Cleavage of
Glycols
H
H C
H
C H
OH OH
R
H
H
C
C R
OH OH
R
R'
R'
C
C R
OH OH
HIO 4
HIO 4
HIO 4
2 H C H + HIO 3
O
2R
C H + HIO 3
O
2R
C R' + HIO 3
O
Haloform Reaction
Methyl carbinol cleavage to give
Carboxylic acids and Haloform
H
CH 3 C H
OH
H
CH 3 C R
OH
X2
OH
X2
OH
H
+
-
HCX 3 + H C OH
O
H+
-
HCX 3 + R
C OH
O
Disguising an Alcohol
Creating a tetrahydropyranyl acetal
Overall Transformation
+
O
+
ROH
H
RO
O
(an acetal)
Dihydr opyran
(DHP)
Mechanism
H
+
-H
O
+
H
H
H
+
H
O
+
O
(a heteroatom -stabilized car bocation)
R OH +
- H+
+
O
R O+
H
O
H+
R O
O
Spectroscopic
Characteristics of Alcohols
Infrared
 Pmr
 Cmr

Ethers




Nomenclature
Properties
Preparation
Reactions
Ether
Nomenclature
Preparation of Ethers
Dehydration of Alcohols
Williamson synthesis
AlkoxymercurationDemercuration
Peroxyacid Epoxidation of
Alkenes
Ether Formation via Acid
Catalyzed Dehydration of
Alcohols
2 ROH
S 1
N
C
+
OH 2
-H2O
H
+
R
O
C+
R
ROH
C
+
OR
-H
H
SN2
C
+
OH 2
ROH
+
OR
C
H
+
H2O
-H
+
+
C
O
R
Williamson Synthesis of Ethers
Bimolecular Substitution by Alkoxide
on a suitable substrate
H
-
+
RO Na + R'
C X
SN 2
H
Primary
Alkyl Halide
H
RO C R' + NaX
H
AlkoxymercurationDemercuration of Alkenes
Markovnikov Addition
 Typically no rearrangements/shifts
 Mercurinium ion involvement

H H
R C C H
R' H
R C C R''
MMR
R'OH
MMR
R'OH
NaBH 4
H
R C
H
C H
OR' H
NaBH 4
R'
R C
H
C R''
OR' H
Where MMR = modified mercury reagent = Mercury trifluoroacetate
Epoxidation of Alkenes
Prilezhaev reaction
H
C C
R
H
H
R
R
C C
H
R
O
O
H
O
R
C
O
R
C O H
O
Ether Reactions
HX Cleavage
 Epoxide Ring Opening

HX Cleavage of Ethers
Unimolecular or Bimolecular
Cleavage Pathways
R
HX
O R
R
+
O R
X- Protonation
H
SN 1
R
+
O R
X-
ROH
R+
X-
RX + ROH
RX
H
SN 2
R
+
O R
H
Epoxide Ring Opening
Unimolecular or Bimolecular
H
S 1
H
O
H
N
R
S 2
N
H
R
H
O
+
H
ROH
H
O
H +H
R
H
H O H ROH R C H
+
+
H C H
-H
R
H
OH
O
H ROH
H C
RO
H
R
RO
OH
CH 2 OR
H 2O
H C
R
CH 2 OR