Page 1 of 4 Chemistry 234 Chapter 22 Problem Set Enol and Enolate Chemistry 1) Circle every α-H in each molecule below. For each, draw its enol tautomer(s). 2) Draw mechanisms for both the acid and base mediated tautomerization of diethylketone. O O O EtO OCH 3 O O O O O H O O H + /H 2 O OH Acid Catalyzed O HO - /H 2 O OH Base Catalyzed
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Page 1 of 4
Chemistry234Chapter22ProblemSet
EnolandEnolateChemistry1) Circleeveryα-Hineachmoleculebelow.Foreach,drawitsenoltautomer(s).
2) Drawmechanismsforboththeacidandbasemediatedtautomerizationofdiethylketone.
O
O
O
EtO OCH3
O O
O
O O
H
O
O H+/H2O OH
Acid Catalyzed
O HO-/H2O OH
Base Catalyzed
Chem.234–Chapter22ProblemSet
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3) Ineachcompoundbelow,rankthelabeledprotonsinorderofincreasingacidity.
4) Drawtheenolateformedwheneachcompoundbelowistreatedtothespecifiedconditions.
5) Predicttheproductsforeachreactionbelow.
O
Ha
Hb Hc
O O
Ha Hb Hc
HO
OO
OHb
Hc
a
O
O
O
O
LDATHF, -78 °C
LDATHF, -78 °C
LDATHF, -78 °C
LDATHF, -78 °C
NaOEtHOEt
NaOEtHOEt
NaOEtHOEt
NaOEtHOEt
O 1. NaOH Br2 (xs)2. H3O+
OBr2
AcOHPyridine
Δ
O NaOHCl2 (xs)
Ph
ONaOHI2 (xs)
Chem.234–Chapter22ProblemSet
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6) Predicttheproductforeachalkylationreactionbelow.
7) Explainwhyeachreactionbelowdoesnotproceedaswritten.
Alkylation-DecarboxylationChemistry8) WhichofthecompoundsbelowwillreadilyloseCO2whenheated?
1. LDA THF, -78 °C
1. NaOEt HOEt
O
2.Br
O
2. I
O1. LDA THF, -78 °C
2. CH3Br
O
O
O
1. NaOEt HOEt2. I
Hint: The enolate will form from the most
acidic α-H
O 1. LDA THF, -78 °C2. I
O
O1. NaOEt HOEt2.
Br
O
O OH
OH
O
OO
OH
OOHOH
O
O
OOH
OCOOH
Chem.234–Chapter22ProblemSet
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9) Predicttheproductsforeachreactionshownbelow.
10) Eachcompoundbelowwaspreparedviathemalonicesteroracetoaceticestersynthesis.Determinethestartingmaterialsusedtoprepareeachofthesecompounds.
EtO OEt
O O
OEt
O O
1. NaOEt2. Br
3. H+/H2O, Δ
EtO OEt
O O 1. NaOEt2. I
1. NaOEt2. I
H+/H2O, Δ
1. NaOEt2.3. H+/H2O, Δ
H3C-Br
OEt
O O1. NaOEt2.
5. H+/H2O, Δ
H3C-Br3. NaOEt4. Ph-CH2-I
OEt
O O 1. NaOEt2.
4. H+/H2O, Δ
BrBr
3. NaOEt
O
OH
OH
O
O
O
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