Alcohols - MSU Denver
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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