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Alcohol Reactions
Conversions to esters (Acetate Lab)
Reactions with hydrogen halides
Acid-catalyzed hydrations
condensation
Fischer esterification
acid catalyzed
reversible
Esterification
ROH H2O+
H+
+R'COH
O
R'COR
O
Example of Fischer Esterification
H2O+
CH3OH+COH
O
COCH3
O
H2SO4
0.1 mol 0.6 mol
70% yield based on benzoic acid
High yields
Not reversible when carried outin presence of pyridine.
Reaction of Alcohols with Acyl Chlorides
ROH HCl+ +R'CCl
O
R'COR
O
analogous to acyl chlorides
Reaction of Alcohols with Acid Anhydrides
ROH + +R'COR
OO
R'COCR'
O
R'COH
O
Primary alcohols
from H2O
Oxidation of Alcohols
RCH2OH
O
RCH
O
RCOH
Secondary alcohols
O
RCR'RCHR'
OH
In aqueous solution:
Mn(VII) Cr(VI)
KMnO4 CrO3/ H2SO4 = H2CrO4
K2Cr2O7 / H2SO4 = H2Cr2O7
Strong Oxidizing Agents
Oxidize 1o alcohols to carboxylic acids.
Cannot stop at aldehydes.
Aqueous Cr(VI)
FCH2CH2CH2CH2OH
K2Cr2O7
H2SO4
H2O
FCH2CH2CH2COH
(74%)
O
Na2Cr2O7
H2SO4
H2O
(85%)
H
OH
O
A.
B.
C.
D.
H2CrO4, acetone 35o C
OH
OH
O
O
OH
O
OH
O
H
O
O
O
What is the product of the following reaction?
Question
Used in CH2Cl2
Pyridinium dichromate (PDC)
(C5H5NH+)2 Cr2O7
2–
Pyridinium chlorochromate (PCC)
C5H5NH+ ClCrO3–
“Collins Reagent”
Specialized Oxidizing Agents[Nonaqueous Sources of Cr(VI)]
Jones Reagent:
CrO3/ H2SO4 acetone
(does not affect Carbon=Carbon double bonds;
oxidizes 2o alcohols to ketones)
Example: Oxidation of a Primary Alcohol with PCC
CH3(CH2)5CH2OHPCC
CH2Cl2
O
CH3(CH2)5CH
(78%)
ClCrO3–
N
H
+
A.
B.
C.
D.
xs PCC, CH2Cl2, 25o C
OH
OH
O
O
OH
O
OH
O
H
O
O
O
What is the product of the following reaction?
Question
Question• For the following reaction, select the statement that
best describes it.
RCH2OH + PDC [(C5H5NH+)2 Cr2O72–] ®
• A) The alcohol is oxidized to an acid, and the Cr(VI) is reduced.
• B) The alcohol is oxidized to an aldehyde, and the Cr(VI) is reduced.
• C) The alcohol is reduced to an aldehyde, and the Cr(III) is oxidized.
• D) The alcohol is oxidized to a ketone, and the Cr(VI) is reduced.
RCH2O
H
CH2R
OH
H+
RCH2O CH2R H OH+
Conversion of Alcohols to Ethers
Acid-catalyzed
Referred to as a "condensation"
Equilibrium; most favorable for primary alcohols
Intramolecular Analogue
HOCH2CH2CH2CH2CH2OH
H2SO4 130°
O
(76%)
via:
O
H
+O
H
H
••••••
Reaction normally works well only for5- and 6-membered rings.
Question • When 1-propanol is treated with
Na2Cr2O7/H2SO4 followed by treatment with
CH3OH, H2SO4 the product isolated is:
• A) propanal B) propanoic acid
• C) propanol D) methyl propanoate
Question
I. Oxidation
II. Reduction
III. Neither oxidation or
reduction
A. I: a, c, d; II: e, f; III: b
B. I: a, d, e; II: c, f; III: b
C. I: c, d, e; II: a, f; III: b
D. I: c, f; II: a, d, e; III: b
E. I: c, e;II: a, d, f; III: b
Classify the following as oxidation, reduction or neither oxidation or reduction