substitution, elimination, addition, and rearrangement reactions promoted by potassium salts ...

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SUBSTITUTION, ELIMINATION, ADDITION, AND
REARRANGEMENT REACTIONS PROMOTED BY POTASSIUM
SALTS SOLUBILIZED BY 18-CROWN-6 ("NAKED" ANIONS)
IN NON-POLAR ANb DIPOLAR APROTIC ORGANIC SOLVENTS
A THESIS
Presented To
The Faculty of the Division of Graduate
Studies and Research
By
Atif Musa Dabdoub
In Partial Fulfillment
of the Requirements for the Degree
Doctor of Philosophy in the School of Chemistry
Georgia Institute of Technology
November, 1976
SUBSTITUTION, ELIMINATION, ADDITION, AND
REARRANGEMENT REACTIONS PROMOTED BY POTASSIUM
SALTS SOLUBILIZED BY 18-CROWN-6 ("NAKED" ANIONS)
IN NON-POLAR AND DIPOLAR APROTIC ORGANIC SOLVENTS
Approved:
Charles (cid:9) Liotta, Chairman
t
A
ames A. - Stanffeld
e s C. V_owers_
Date approved by Chairman:HOV 22 1976
To my parents
111
ACKNOWLEDGMENTS
The author wishes to express his sincere appreciation
to his research director, Dr. Charles L. Liotta, for his un-
limited guidance, encouragement and assistance throughout the
course of this work.
Drs. James A. Stanfield and James C. Powers are grate-
fully thanked for reading and critically evaluating this
manuscript. Numerous useful discussions with Drs. Edward M.
Burgess, Erling,J. Grovenstein,and ,Leon. (cid:9) Zalkow are grate-
fully appreciated as are those discussions and contributions
given me by fellow graduate students'and friends (especially
Drs. Fred L. Cook and Henry P. Harris).
The Department of Chemistry of Georgia Institute of
Technology is thanked for the Teaching ASsistantship granted
during this work. Thanks are also due to Dr. Charles L.
Liotta for the Research Assistantship granted to the author
during the first two Summer quarters of this work.
Above all, the author is forever grateful to his par-
ents and family for their encouragement, help, and financial
support.
iv
TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS (cid:9) iii
LIST OF TABLES (cid:9) vi
LIST OF ILLUSTRATIONS (cid:9) vii
SUMMARY (cid:9) ix
Chapter
I. INTRODUCTION, CROWN ETHERS (cid:9) 1
"Naked" Anion
Nomenclature
-
Biological Utilization of Crown Ethers
Cationic Complexes of Crown Ethers;
Phase-Transfer Catalysis, SolvatiOn,
Solubility, and Nucleophilicity
Crown Ethers as Reagents and Catalysts'
Literature Review of the Utility of Crown
Ethers in Substitution, Addition, and
Elimination. Reactions
II. EXPERIMENTAL (cid:9) 46
Instrumentation
Chemicals -,- _
Elimination Reactions Promoted by "Naked"
Halides
Solubilities of "Naked" Anions in Solution
Determination of Salt Concentrations in
Solution , (cid:9) _ (cid:9) _
Concentration of Potassium Bromide in
Solution
Displacement and -Rearrangement Reactions
Promoted,by "Naked" Cyanide
Addition Reactions Performed with "Naked"
Cyanide and Acetone Cyanohydrin: Hydro-
cyanation of 0-Cholestene-3-one
Displacement and Elimination Reactions:
Reactions of Potassium Cyanide and
Potassium Acetate with Organic Substrates
under Liquid-Liquid Phase-Transfer Cataly-
tic (Heterogeneous) Conditions
V
Page
Displacement and Elimination Reactions
Promoted by "Naked" Cyanide , - -
Displacement and Elimination Reactions
Promoted by "Naked" Acetate -
III. RESULTS AND DISCUSSION (cid:9) 120
Solubilities of "Naked" Anions in Solution-
Reactions Utilizing 18-Crown-6
Elimination Reactions Promoted by "Naked"
Halides f
Substitution, Elimination, and Addition
Reactions Promoted by "Naked" Cyanide
Reactions of "Naked" Cyanide with 2-Chloro-
2-methylcyclohexanone and with 2-Cyano-2-
methylcyclohexanone under Solid-Liquid
Phase Transfer Catalysis (cid:9) _
Additi-on Reactions Performed'with ,"Naked"
Cyanide and Acetone Cyanohydrin
Conjugate Hydrocyanation of ot,-Unsaturated
Ketones
Nitrile Syntheses
Reactions of "Naked" Cyanide with Organic
Substrates under Liquid-Liquid Phase- --
TransfetCatalytic Conditions (cid:9) _
Acetate Synthesis
Reactions of "Naked" Acetate with Organic
Substrates under Liquid-Liquid Phase-
Transfer Catalytic Conditions .
IV. CONCLUSIONS (cid:9) 178
V. RECOMMENDATIONS (cid:9) 183
APPENDICIES (cid:9) 185
REFERENCES AND NOTES (cid:9) 209
VITA (cid:9) 224
vi
LIST OF TABLES
(cid:9)
Table Page
1. Solubility of KBr in Acetonitrile at 25°C in the
Presence and in the Absence of 18-Crown-6 (cid:9) 61
2. Solubilities of KI, KBr, KOAc, and KCN in
Acetonitrile at 25°C (cid:9) 64
3. Solubilities of Potassium Salts in Acetonitrile
at 25°C in the Presence and in the Absence of
(cid:9)
18-Crown-6 122
4. Solubility of Potassium Fluoride in Acetonitrile
and in Benzene at 25°C in the Presence and in the
Absence of 18-Crown-6 (cid:9) 123
5. Solubility of Potassium Acetate in Acetonitrile
and Benzene Solutons'Of 18-CrOwn6 (cid:9) 124
6. Reactions. of PotaSsium,Cyanide with 2-Chloro-2-
methlbyclohexanone and With 2-Cyano-2-methyl-
cyclohexanone with and without 18-Crown-6-under
Solid-Liquid Phase-Transfer Catalysis . (cid:9) 132
7. Hydrocyanation'of A4.-Cholesten-3-one with "Naked"
Cyanide and Acetone'Cyanohydrin under Solid-Liquid
Phase-Transfer Catalysis (cid:9) 159
8. Reactions of 'Potassium Cyanide with Organic Sub-
strates in the Presence and in the Absence of
18-Crown-6 under Liquid-Liquid Phase-Transfer
Catalysis (cid:9) 166
9. Reactions of Potassium Acetate with Organic Sub-
strates in the Presence and in the Absence of
18-Crown-6 under Liquid-Liquid Phase-Transfer
Catalysis (cid:9) 173
LIST OF ILLUSTRATIONS
Page
1. 18-Crown-6 Complexation with Alkali Metal
Ctions (e:q., 1C4 ) (cid:9) 7
2. Structures of 18-Crown-6, 15-Crown-5 and
12-Crown-4 with an Estimate of Their Respec-
tive Cavity Diameters and the Ionic Diameters
of Some Simple Alkali-Metal Cations (e:g., -e,
Na+ and Li+) (cid:9) 8
3. Course of Liquid-Liquid Phase-Transfer Catalysis
by Quaternary Salts. IonPairs are Enclosed in
Square Brackets (cid:9) 14
4. Course of Solid-Liquid Phase-Transfer Catalysis
by Crown Ethers (cid:9) 15
5. Solubility of Potassium Salts in Non-Polar and
Dipolar Aprotic Solvents (cid:9) 17
6. Thermodynamic Cycle for the Solubilization
Process of a Metal-Ion Salt in Crown-Solvent_
System in the Hypothetical One Molal Infinite
Dilution State (cid:9) 17
7. Solvation of the Cyanide Ion with the Cyano
Group of Acetonitrile (cid:9) 19
8. Plot of Scale Divisions Versus Concentration of
Potassium Bromide in 0.15M 18-Crown-6,racetoni-
trile Solution at 25°C (cid:9) 65
9. Plot of Scale Divisions Versus Concentration of
Potassium Iodide in 0.15M 18-Crown-67s:acetoni-
trile Solution at 25°C (cid:9) 66
10. Plot of Scale Divisions Versus Concentration of
Potassium Iodide in Acetonitrile at 25 °C . . . . (cid:9) 67
11. Plot of Scale Divisions Versus Concentration of
Potassium Azide in 0.15M 18-Crown-6-acetoni-
trile at 25°C (cid:9) 68
Figure Page
12. Plot_of Scale Divisions Versus Concentration
of Potassium Thiocvanate in 0.15M 18-Crown-6-
Acetonitrile at 25°C (cid:9) 69
13. Displacement and Elimination Reactions Effected
by "Naked" Halides on 2-Chloro-2-methylcyclo- (cid:9)
hexanone 127
14. Mechanistic Pathway for the "Favorskii Rear-
rangement Product" of 2-Chloro-2-methylcyclo-
hexanone Promoted by "Naked",Cyanide (cid:9) 131
15. Proposed Mechanism for the Reaction of "Naked"
Cyanide with 2-Chloro-2-cyano-4-methylcyclo-
hexanone (cid:9) 140
16. Racemization of Optically Active 1-Chloro-l-
phenylethane with "Naked" Cyanide-acetoni-
trile Solution (cid:9) 145
0"1(10)_
17. Scheme for the Prepar4 io Octalin-
3-one and 9-Methyl-,,I "octalin-3-one . . (cid:127) (cid:127) (cid:9) 163
1
ix
SUMMARY
The work described in this thesis involved studies of
the effects of 18-crown-6 on the solubility and reactivity
of potassium salts in non-polar and dipolar aprotic organic
solvents.
The solubilities. of a variety of common potassium
salts in acetonitrile at 25°C in the presence and in the
absence of 18-crown-6 were measured:using a Coleman Model-21
Flame Photometer. The order of solubilities. of potassium
,
salts ia 0.15M 187crown-6-acetonittilerSolution at 25 °C was
found to be KSCN:-KI > KN. = KBr = KCN (cid:9) KOAC ,%> .-KC1 > KF.
3
The solubility enhancement caused by the presence of 18-
crown-6, is quite'dramatid !lor . kCi, KCN,and,KOAc '(greater
than 102),.only moderate for' KBr and KN3 (greater than 50),
and marginal for KF, KIt and KSCN. It should be noted that
KI and KSCN already have high inherent solubilities in pure
acetonitrile.
It has been found that the solubilization of alkali
metal salts in polar and non-polar aprotic organic solvents
by 18-crown-6 leaves the companion anions weakly solvated.
These are referred to as "naked" anions. These species have
been found effective in promoting dehydrohalogenation . of 2-
chloro-2-methylcyclohexanone, a substrate subject to '"Favor-
skii rearrangements":in the non-polar and_dipolar aprotic