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University Micrdnlms International 7908232 WANG, YING STUDY OF THE FORMATION AND REACTIVITY OF ORGANIC CATIONS IN SOLUTION BY THE PULSE RADIOLYSIS METHOD. THE OHIO STATE U N IV E R S IT Y , P H .D ., 1978 International 300 n. zees roao. ann a rb o r, mi abioe STUDY OF THE FORMATION AND REACTIVITY OF ORGANIC CATIONS IN SOLUTION BY THE PULSE RADIOLYSIS METHOD DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Ying Wang, B.S., M.S. The Ohio State University 1978 Reading Committee; Approved hy Richard F. Firestone Jack Hine Leon M. Dorfman Adviser Department of Chemistry TO MY PARENTS ACKNOWLEDGMENT I wish to thank my adviser, Professor Leon M. Dorfman, for his constructive comments and constant encouragement throughout the course of this investigation. I also wish to express my appreciation to Professor Jack Hine for helpful discussion on the subject of structure-reactivity relationship and to Mr. Ed Ray for maintaining the electronic equipment. I am grateful to the Department of Chemistry of The Ohio State University and to the United States Department of Energy for their financial support. Finally, I wish to thank my wife, Shu-Han, for her patience, understanding, and support throughout the course of this work. June 2, 1950 --- B o m - Taiwan, China 1968-1972....... B.S., National Chung-Hsing University,' Taiwan 1972-1974....... Military service 1974-1976 .... Teaching Associate, Department of Chemistry, The Ohio State University, Columbus, Ohio 1974-1976 .... M.S., The Ohio State University, Columbus,,Ohio .1976-1978....— Research Associate, Department of Chemistry, The Ohio State University, Columbus, Ohio PUBLICATIONS (1) "The Formation of Carbénium Ions, Carbanions and Carbanioh-Pairs in Irradiated Solutions, and the Reactivity of These Intermediates" Leon M. Dorfman, Ying Wang, Hsien-Yien Wang, and Richard J. Sujdak, Faraday Discussion No. 6 3, radiation effects-63/l3(l976). (2) "Fast Reaction Studies of Carbanions and Carbocations in Solution" Leon M. Dorfman, Vincent M. DePalma and Ying Wang, in "Protons and Ions Involved in Fast Dynamic Phenomena", Elsevier Scientific Publishing Co., 1978, Proceedings of 30th Meeting of Société de Chimie Physique, Paris, November 1977. (3) "The Reactivity of Arylcarbénium Ions with Alkylamines and Ammonia in Solution: Kinetic Effect of Cyclopropyl Substitution; Solvent Effect" Vincent M. DePalma, Ying Wang, and Leon M. Dorfman, J. Amer. Chem. Soc., 100, 5416(1978) (4) "The Reactivity of Arylcarbenium Ions with Alkenes", Ying Wang and Leon M. Dorfman, in preparation. (5) "Formation Mechanism of Arylcarbénium Ions in the Irradiated 1 ,2-Dichloroethane solution", Ying Wang, John Tria, and Leon M. Dorfman, in preparation. TABLE OF CONTENTS Page ACKNOWLEDGMENT ..................................... ii VITA ............................................... iii LIST OF TABLES ..................................... vi LIST OF FIGURES .................................... vii LIST OF SYMBOLS AND ABBREVIATIONS .................. xiii INTRODUCTION ....................................... 1 I. Carbénium Ions ............................ 1 II. Carbénium Ions Formed by Ionization Radiation...3 EXPERIMENTAL ....................................... 12 . I. Pulse Irradiation ......................... 12 II. Optical Detection ......................... l4 III. Reaction Cells ........................... 22 IV. Sample Preparation ........................ , 28 V. Dosimetry................................ 33 VI. Data Analysis ............................ 33 VII. Materials ................................ 36 RESULTS AND DISCUSSION ..... 40 I. Mechanism of the Formation of Arylcarbénium Ions in the Irradiated 1 ,2-Dichloroethane Solution .............................. 40 Yield Curve Studies ...................... 4l Competition Kinetics ..................... 6l Titration Experiments .................... 82 Proposed Mechanism ....................... 95 iv TABLE OF CONTENTS (continued) II. Reactions Between Arylcarbenium Ions and Alkenes ....................... IO9 Possible Reaction Path ................... 112 Ethylene, Propylene, Isobutylene, and Cyclohexene .............................. II6 Ethylene, Propylene, Neohexene, and Allylbenzene ........... 129 Propylene, 1,3-Butadiene, Cyclohexene, and 1»3-Cyclohexadiene ....................... 136 1 .3-Butadiene, 2-Methyl-1,3-butadiene, 2.3-Dimethyl-l,3-butadiene, 4-Methyl-l,3- pen tadiene, and 2,4-Dimethyl-l,3-pentadiene..146 APPENDIXES ......................................... 161 A. Competition Kinetics - Two Solutes Competing for One Solvent Cation .................... I6I B. Competition Kinetics - Two Solutes Competing for Two Solvent Cations ................... I63 C. Pseudo-First Order Rate Equation with Overlapping Absorption .................... I66 D. Calculations of AH's for Reactions between Benzyl Cation and Alkenes ................. l6? REFERENCES AND NOTES ............................... I69 LIST OF TABLES Table Page 1. Solubilities of alkene gases in 1,2-DCE at 25°C ................................ 32 2. Rate constants between several carbénium ions and ammonia at 24 C in 1,2-DCE ..... 87 3. Propagation rate constants for the cationic polymerization of styrene ...... Ill 4. Rate constants for reactions between benzyl cation and alkenes in 1,2-DCE at 24^C.................................... 122 5. Gas phase carbénium ion affinities of olefins................................. 12? 6. Rate constants for reactions between benzyl cation and alkenes in 1,2-DCE at 24°C................................. 134 7. Rate constants for reactions between benzyl cation and alkenes in 1,2-DCE at 24°C ................................ 143 8. Rate constants for reactions between benzhydryl cation and 1.3-conjugated dienes in 1,2-DCE at 24°C ............... 156 9. Calculations of AH's for reactions between benzyl cation and alkenes in gas phase .............................. l68 10. Summary of the rate constants for the reactions between arylcarbenium ions and alkenes in 1,2-DCE at 24 C .......... l60 LIST OF FIGURES Figure Page 1. Schematic diagram of the inhomogeneous distribution of the primary species formed in the irradiated liquid.................. 6 2. The optical absorption spectra of benzyl cation, benzhydryl cation, and trityl cation ............................. 10 3. Time profile of an 85 ns pulse and a 600 ns pulse ....................... 15 4. Schematic diagrams of the double pass optical detection system and of the single pass detection system..................... 17 5. Spectral radiant energy distribution for Rudolph xenon lamp with 450 watt bulb .... 19 6. Time profile of xenon flash at 405 nm .... 20 7. Spectral responses of phototubes with s-1, s-5 , and s-19 response .............. 23 8. Reaction cells used in pulse radiolysis experiments .............................. 25 9. A cryostat used in temperature dependent experiment ............................... 27 10. Apparatus used for the determination of solubility of gas in 1 ,2-dichloroethane solution ................................. 30 11. Two typical oscilloscope traces showing formation following the pulse and decay following the pulse ...................... 34 12. The plot of optical density at 364 nm vs. the concentration of dibenzylmercury in the irradiated dibenzylmercury-1,2-DCE solution..44 1 3. The time dependent spectrum resulting from irradiation of a O.OO55 M solution of dibenzylmercury in 1,2-DCE under vacuum.... 45 vii LIST OF FIGURES (continued) Figure Page 14. The time dependent spectrum of irradiated propylene-dihenzylmercury-l,2-DCE solution