EQUILIBRIA OF ALUMINUM CHLORIDE WITH HYDROGEN CHLORIDE IN AROMATIC ...

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EQUILIBRIA OF ALUMINUM CHLORIDE WITH HYDROGEN CHLORIDE
IN AROMATIC HYDROCARBONS
Dissertation
Presented in Partial Fulfillment of the Requirements for
the Degree Doctor of Philosophy in the Graduate
School of The Ohio State University
By
LEWIS DELMAR SWAN, B. A., M. Sc.
The Ohio State University
1952
Approved by
vxser/’
TABLE OF CONTENTS
Page
I. Purpose............................... 1
II. Historical............................. 2
Part A. The HX-AIX,- Aromatic Solvent . 2
Part B. The Catalytic Species in the
Friedel-Crafts Reaction. . . . 3
III. Preliminary Observations............... 16
A. Benzophenone-Aluminum chloride
Complex.......................... 16
B. Effect of repeated sublimation
of aluminum chloride .............. 17
C. Catalytic couple with mercury salts. 17-
D. Effect of moisture.......... .17
E. Preliminary studies with hydrogen
chloride........................ IS
IV. The Specific Problem............ .. .30
V. Experimental...........................31
A. Apparatus........................ 31
B. Purification and Preparation of
Reagents........................ 36
1. Aluminum chloride.........36
2. Hydrogen chloride.........38
3. Aromatic Hydrocarbons. . . . 42
a. benzene......... . . .42
b. toluene...............43
c. mesitylene.............45
4. Benzophenone............... .45
5. Miscellaneous: 02> HgO, N2. . 46
C. Operational Procedures...........47
D. Analytical Procedures.............50
E. Summary of manipulatory difficulties
encountered..................... . . 52
VI. Data....................................53
A. Benzene as Solvent...............53
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TABLE OF CONTENTS
(continued)
Page
a. No complex without promoter. . . 53
b. Complex with promoter, . . . . . 56
c. Equilibrium constant......... 56
B. Toluene as Solvent....................56
a. Toluene versus time. ..........56
b. Complex with promoter........ 62
c. Equilibrium constant........62
C. Mesitylene as Solvent.................67
a. No complex without promoter .. . 67
b. Complex......................67
c. Equilibrium constant........ 67
d. Effect of oxygen . ........... 72
VI. Discussion of Results...................... 74
a. No Hydrogen chloride-aluminum
chloride addition compound . . . 74
b. High aluminum chloride-benzo-
phenone ratios ................ 74
c. Inorganic catalytic couples. . . 75
d. Repeated sublimation of aluminum
chloride.....................75
e. Importance of promoters...... 76
f. Relative basicity of solvent . . 77
g. The role of water and oxygen . . 7S
h. Ternary complexes............ 79
i. Evidence for hydrates......... 79
j. Evidence for dimer........... SO
k. "Red oil” complications...... SO
1. Distribution of aluminum chloride Si
91. Effect of oxygen on aluminum
chloride-mesitylene system . . . S2
VII. Future Problems............................S3
VIII. Suranary............. S5
Autobiography. . , ,
LIST OF TABLES
No.
I. Solubility of Aluminum Chloride in
Benzene-Benzophenone Solutious at
20°C. (Molality xlo3)
II. Effect of Repeated Sublimation on
Solubility of Aluminum Chloride in
Benzene at 20°C.
III. Effect of Water on the Aluminum Chloride
Benzophenone Ratio in Benzene at 20°C.
IV. Effect of Aqueous Hydrogen Chloride
on Aluminum Chloride Solubility in
Benzene at 20°C.
V. Effect of Hydrogen Chloride Atmosphere
on Solubility of only Partially Pure
Aluminum Chloride in Benzene at 20°C.
VI. Promoting Effect of Water on Coordina­
tion of Aluminum Chloride with Hydrogen
Chloride in Benzene at 20°C.
VII. Co-ordination of Hydrogen Chloride with
Aluminum Chloride in the Presence of
Water in Benzene at 25°C.
VIII. Effect of Water on the Solubility of
Aluminum Chloride in Benzene with
Subsequent Effects of Hydrogen Chloride
and Water at 25°C.
IX. Effect of Time on the Solubility of
Aluminum Chloride in Toluene at 25°C.
with Effect of Subsequent Water
Addition.
X. Co-ordination of Aluminum Chloride
with Hydrogen Chloride in Toluene at
25°C.
XI. The Solubility of Aluminum Chloride in
Mesitylene Versus Time at 25°C. with
Subsequent Air Admission,
V
LIST OF TABLES
(continued)
Page
XII. Solubility of Aluminum Chloride in
Mesitylene at 25°C. as Affected by
Hydrogen Chloride Addition and
Subsequent Removal by Pumping. 70
XIII. Effect of Oxygen on Aluminum Chloride-
Mesitylene System at 25°C. 73
LIST OF FIGURES
Page
1. Effect of Benzophenone on Solubility of
Aluminum Chloride in Benzene at 20°C. 20
2. Effect of Water on Aluminum Chloride-
Benzophenone Ratio in Benzene at 20 C., 23
3. Effect of Aque;ous Hydrogen Chloride on
the Solubility of Aluminum Chloride in
Benzene at 20'G. o c
4. Preliminary Run.Effect of Atmosphere of
Hydrogen Chloride on the Solubility of -
Aluminum Chloride in Benzene at 20°C. 27
5. Equilibration Flask used in Aluminum
Chloride-Benzophenone System. 2S
6. Equilibration Vessel. 1/2 Scale 32
7. Sampling Flask. Full Scale 34
S. Manifold for Introduction of Hydrogen
Chloride to System. 35
9. Aluminum Chloride Sublimation Manifold. 37
10. Block Diagram for Filling Hydrogen Chloride
Addition Bulbs. 39
11. Hydrogen Chloride Addition Bath. 41
(Shown in Filling Position) 1-/2 Scale
12. Block Diagram for Purification and Addition
of Solvent to System. 44
13. Benzene, Aluminum Chloride, Hydrogen
Chloride, with Subsequent Water Addition.25 C.55
14. Benzene, Aluminum Chloride, Hydrogen Chloride
Showing Effect of Water and Oxygen.2$°C. 56
15. Effect of Water on Solubility of Aluminum
Chloride in Benzene.Subsequent Addition of
Hydrogen Chloride and Water at 25°C. 60
16. Solubility of Aluminum Chloride in Benzene
at 25°C. as Influented'.by the Presence of
Water. 61
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LIST OF FIGURES
(continued)
No. Page
17. Effect of Time on the Solubility of
Aluminum Chloride in Toluene at 25°C.
with Subsequent Water Addition. 64
IS. Solubility of Aluminum Chloride in Toluene
at 25°C. as Influenced by Hydrogen Chloride. 66
19. Aluminum Chloride in Mesitylene Versus
Time at 25°C. with Subsequent Air Admission. 69
20. Aluminum Chloride in Mesitylene at 25°C. with
Added Hydrogen Chloride, Followed by Pumping. 71
ACKNOWLEDGMENT
Appreciation to Dr. Alfred B. Garrett for his
suggestion of the problem and his guidance during the
work is gratefully extended.
Acknowledgment is also due the Office of Naval
Research, United States Navy, and the du Pont Company
for fellowships which enabled the completion of this
work.
The author also wishes to express his gratitude
to his wife for her patience and understanding during
the period of this study.
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EQUILIBRIA OF ALUMINUM CHLORIDE WITH HYDROGEN CHLORIDE IN
AROMATIC HYDROCARBONS
I. Purpose
The purpose of this investigation was to study the
equilibria of aluminum chloride with hydrogen chloride in
aromatic hydrocarbons as solvents. This is part of a pro­
gram of elucidating the nature of Friedel-Crafts catalysis.
Previously reported work has indicated that the true
catalyst in those reactions ordinarily promoted by aluminum
chloride might actually be tetrachloroaluminic acid formed
in the equilibrium:
AICI3 + HC1 HA1C14.
Although this substance has never been isolated and
does not form in the absence of a solvent1, its salts of
1. H. C. Brown and H. W. Pearsall, J. Am.Chem.Soc., 73,
4631 (1951).
2 3
the form R+ AlCl^" are known (in the presence and
absence of solvent).
2. E. Wertyporoch & T. Firla, Z.physik.chem., 162, 393-414
(1932).
3. Thomas, C. A., Anhydrous Aluminum Chloride in Organic
Chemistry, Am. Chem. Soc. Monograph #37, New York,
Reinhold Publishing Co., 1941, P 43-56.
------------- j-----------------------------------
It was proposed:
1. To measure the solubility of aluminum chloride in aro­
matic solvents, specifically benzene, toluene, and mesit­
ylene, at 25° C.;
2. To measure the solubility of aluminum chloride in
hydrogen chloride solutions of the same aromatic hydro­
carbons at several concentrations and at the same tempera­
ture;
3. To calculate equilibrium constants for the reaction
indicated above if the reaction did not go to completion;
and
4. To study the effect of moisture and oxygen on the
equilibria involved.
II. Historical
Part A. Data on the hydrogen chloride-aluminum chloride-
aromatic solvent systems. Brown and Pearsall^ studied the
4. H. G. Brown and H. ¥. Pearsall, J.Am.Chem. Soc., 74,
191 (1952). ~
system hydrogen chloride-aluminum chloride-toluene at
-45.5° C. and -B0° C. Applying Henry’s law to their vapor
pressure data they found co-ordination of hydrogen chloride
and aluminum chloride in toluene.
5
Ipatieff and Komerewsky treated hydrogen chloride-