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The Effect of Stabilizing Groups on the Extent of Long-Range ΀ Electron Western Michigan University ScholarWorks at WMU Dissertations Graduate College 8-1976 The Effect of Stabilizing Groups on the Extent of Long-Range Π Electron Participation and the Effect of the Negative Charge on the Chemical Shift of Neighboring Protons in Carbanions Atilla Tuncay Western Michigan University Follow this and additional works at: https://scholarworks.wmich.edu/dissertations Part of the Organic Chemistry Commons Recommended Citation Tuncay, Atilla, "The Effect of Stabilizing Groups on the Extent of Long-Range Π Electron Participation and the Effect of the Negative Charge on the Chemical Shift of Neighboring Protons in Carbanions" (1976). Dissertations. 2826. https://scholarworks.wmich.edu/dissertations/2826 This Dissertation-Open Access is brought to you for free and open access by the Graduate College at ScholarWorks at WMU. It has been accepted for inclusion in Dissertations by an authorized administrator of ScholarWorks at WMU. For more information, please contact [email protected]. THE EFFECT OF STABILIZING GROUPS ON THE EXTENT OF LONG-RANGE 7 f ELECTRON PARTICIPATION AND THE EFFECT OF THE NEGATIVE CHARGE ON THE CHEMICAL SHIFT OF NEIGHBORING PROTONS IN CARBANIONS by Atilla Tuncay A Dissertation Submitted to the Faculty of the Graduate College in partial fulfillment of the Degree of Doctor of Philosophy Western Michigan University Kalamazoo, Michigan August 1976 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. THE EFFECT OF STABILIZING GROUPS ON THE EXTENT OF LONG-RANGE I f ELECTRON PARTICIPATION AND THE EFFECT OF THE NEGATIVE CHARGE ON THE CHEMICAL SHIFT OF NEIGHBORING PROTONS IN CARBANIONS Atilla Tuncay, Ph.D. Western Michigan University, 1976 2 .4-Diphenylbicyclo octa-2,6-diene, 2 ,4-diphenylbicyclo [^3.2.lj oct-2-ene and trans-1 ,3-diphenylpropene were synthesized and their base-catalyzed hydrogen-deuterium exchange rates were measured. Examination of the rate data showed that all three hydro­ carbons underwent exchange at essentially the same rate. It was thus concluded that the extent of long-range ' t f participation in delocalizing a negative charge is a function of the stability of the developing carbanion. 2.4-Diphenylbicyclo |j3.2.lj octa-2,6-diene was converted to its anion by means of n-butyllithium in THF-ds-hexane. Examination of the nmr spectrum of carbanion showed a close similarity to that of the completely delocalized homoaromatic bicyclo |^3.2.lJ octa- 2,6-dienyl anion. It was thus concluded that anisotropic effects due to charge delocalization at C 2 3 u must play a much more important role in influencing changes in the chemical shifts of carbanions, than previously anticipated. Therefore, conclusions regarding long-range *7Y interactions, homoaromaticity and homoaromatic ring current effects must be arrived at by examining not only the proton nmr spectrum of the anion under consideration but also its stability relative to a suitably chosen reference system. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ACKNOWLEDGEMENTS I am deeply indebted to my research advisor, Dr. G.B. Trimitsis, for his untiring assistance and understanding during the course of this work. I am also grateful to Dr. D.C. Iff land, Dr. R.E. Harmon and Dr. M.E. McCarville for their help. Special thanks are due to Dr. G. Slomp, T. Schahil and S. Mizsak of the Upjohn Company for their assistance in obtaining the nmr spectra. Finally, I wish to acknowledge the financial assistance received from the Chemistry Department in the form of teaching assistantships and the Graduate School for associateships. Atilla Tuncay Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. INFORMATION TO USERS This material was produced from a microfilm copy of the original document. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the original submitted. The following explanation of techniques is provided to help you understand markings or patterns which may appear on this reproduction. 1.The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)”. If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting thru an image and duplicating adjacent pages to insure you complete continuity. 2. When an image on the film is obliterated with a large round black mark, it is an indication that the photographer suspected that the copy may have moved during exposure and thus cause a blurred image. You will find a good image of the page in the adjacent frame. 3. When a map, drawing or chart, etc., was part of the material being photographed the photographer followed a definite method in "sectioning" the material. It is customary to begin photoing at the upper left hand corner of a large sheet and to continue photoing from left to right in equal sections with a small overlap. If necessary, sectioning is continued again - beginning below the first row and continuing on until complete. 4. The majority of users indicate that the textual content is of greatest value, however, a somewhat higher quality reproduction could be made from "photographs" if essential to the understanding of the dissertation. Silver prints of "photographs" may be ordered at additional charge by writing the Order Department, giving the catalog number, title, author and specific pages you wish reproduced. 5. PLEASE NOTE: Some pages may have indistinct print. Filmed as received. Xerox University Microfilms 300 North Zeeb Road Ann Arbor, Michigan 40106 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 7 6 -2 3 ,5 7 0 TUNCAY, Atilla, 1948- THE EFFECT OF STABILIZING GROUPS ON THE EXTENT OF LONG-RANGE 7T ELECTRON PARTICIPATION AND THE EFFECT OF THE NEGATIVE CHARGE ON THE CHEMICAL SHIFT OF NEIGHBORING PROTONS IN CARBANIONS, Western Michigan University, Ph.D., 1976 Chemistry, organic Xerox University MicrofilmsAnn , Arbor, Michigan 48106 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TO SELMA iii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS CHAPTER PAGE I. INTRODUCTION ......................................... 1 II. HISTORICAL ......................................... 2 III. STATEMENT OF P R O B L E M ................................... 24 IV. RESULTS AND DISCUSSION................................. 26 A. Preparation of Starting Materials ............... 26 B. The Effect of Stabilizing Groups on the Extent of Long-Range ')[' Electron Participation in Carbanions.......................................... 33 C. Effect of the Negative Charge on the Chemical Shift of Neighboring Protons in Carbanions Devoid of Long-Range Interactions ................ 54 V. EXPERIMENTAL........................................... 67 A. G e n e r a l ............................................ 67 B. Preparation of Starting Materials ............... 68 C. Preparation of the 2,4-Diphenylbicyclo [3.2.l] octa-2,6-diene Anion (78) 85 D. Kinetic Procedure ............................... 87 VI. SUMMARY ............................................... 91 VII. BIBLIOGRAPHY........................................... 93 VIII. V I T A .......................................... 98 iv Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF TABLES TABLE PAGE 1. Second-Order Rate Constants of Hydrogen-Deuterium Exchange of Hydrocarbons .............................. 37 2. Relative Rates of Solvolysis of 7-Norbornenyl and 7-Norbornyl p-Nitrobenzoates in Dioxane-Water at 2 5 ° ...................................................... 47 3. Relative Rates of Solvolysis of 1-Aryl-l-cyclo- propyl-l-ethyl and 2-Aryl-3-methyl-2-butyl p- Nitrobenzoates in 80% Acetone at 2 5 ° ................... 49 4. Relative Rates of Solvolysis of 2-Aryl-2-norbomenyl p-Nitrobenzoates in 80% Acetone at 2 5 ° ................. 51 5. Relative Rates of Solvolysis of 5-Methyl-2-aryl-2- norbornenyl p-Nitrobenzoates in80% Acetone at 25° . 52 6. Summary of NMR Data for Hydrocarbon G5 and its Corresponding Anion 78 61 7. Summary of NMR Data for Hydrocarbon ^42 and its Corresponding Anion 4 > 4 ..................................62 8 . Extent of Deuterium Incorporation as a Function of T i m e .................................................. 90 v Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF FIGURES FIGURE PAGE 1. Graphic depiction of HMO energies of cyclopentadienyl anion j j ............................. 4 2. Graphic depiction of HMO energies of pentadienyl anion j i ................................... 4 3. HMO energy levels for cyclopropenyl anion 11 and allyl anion 1. ................................. 6 4. HMO energy levels for cycloheptatrienyl anion 1J3 . 7 5. Typical first order plot of the base-catalyzed hydrogen-deuterium exchange in 2,4-diphenylbicyclo [3.2.1] oct-2,6-diene ( 6 5 ) ............................. 38 6. Typical first order plot of the base-catalyzed hydrogen-deuterium exchange in 2,4-diphenylbicyclo [3.2.1] oct-2-ene (66) ................................. 39 7. Typical first order plot of the base-catalyzed hydrogen-deuterium exchange in
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