Equilibrium and Exchange Rate Studies in Sulfur Monochloride, Thionyl Chloride and Related
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AN ABSTRACT OF THE THESIS OF SAMUEL CLEMMER DALTON for the Ph, D. (Name of student) (Degree) in CHEMISTRY presented onafrettiA/09 (Major) (Date) Title:EQUILIBRIUM AND EXCHANGE RATE STUDIES IN SULFUR MONOCHLORIDE, THIONYL CHLORIDE AND RELATED SYSTEMS Redacted for Privacy Abstract approved: T. H. Norris The phase diagram for the system sulfur monochloridetetra- ethylammonium chloride has been determined.The system was found to exhibit a miscibility gap throughout abroad concentration and tem- perature range. No evidence for adductformation between sulfur monochloride and tetraethylammonium chloride was obtained.This fact was of interest with regard to radiochlorineexchange studies between sulfur monochloride and thionyl chloride, the resultsof which are described below. Pressure--composition studies have been conducted for the systems thionyl chloride- -tetraethylammoniumchloride, thionyl chloride- -tetra-methylammonium chloride, sulfurmonochloride- - tetraethylammonium chloride, sulfur dioxide- -tetraethylammonium chloride and sulfur dioxidetetramethylammonium chloride.Evi- dence for the following previously unreported compounds wasfound: (CH)NC1 SOC12, 2( CH) NC1. SOC12, 2( CH)NC1 SO2' and 254 34 2 54 (C2H5)4NC1 SO2. No evidence was found for adduct formation be- tween sulfur monochloride and tetraethylammonium chloride.The preparation of the solid adduct (C2H5)4NC1SOC12 was of particular interest with regard to studies of chloride catalysis of the radiochlor- ine exchange described later. A spectrophotometric study of possible adduct formation, in acetonitrile solution, in the systems sulfur monochloride--tetraethyl- ammonium chloride and thionyl chloride--tetraethylammonium chlor- ide has been made. No evidence was found for adduct formation be- tween sulfur monochloride and tetraethylammonium chloride.How- ever, evidence for a solution species involving thionyl chloride and tetraethylammonium chloride, absorbing strongly in the ultraviolet, was found.No quantitative information concerning the stoichiometry and stability of this species could be obtained, however, even with total vacuum line techniques, due to low levels of contamination by water. The rate of exchange of chlorine-36 between sulfur monochlor- ide and thionyl chloride under various conditions has been studied in the pure mixed solvents.The radiochlorine exchange was found to be moderately slow in the two component system (t1/2'A' 0.5 days, N 150 0°C) andvery slow in the presence of elemental sulfur (t112 days, 0°C).The systems exhibited a high degree of irreproducibility in the experimental exchange rates. As a result, no kinetics informa- tion could be obtained for the uncatalyzed exchange.The Arrhenius energy of activation for exchange in equimolar systems in the pres- ence of sulfur was found to be 13.5 ± 4.0 kcal/mole. The effect of very low concentrations of the Lewis base chloride ion (tetraethylammonium chloride) on the rate of radiochlorine ex- change between sulfur monochloride and thionyl chloride in the pres- ence of sulfur has been investigated.Chloride ion has been found to exhibit a pronounced catalytic effect on the rate of this exchange.In excess thionyl chloride the kinetic order of the exchange reaction appeared to be about two.The high degree of irreproducibility in the radiochlorine exchange rates prevented further study of the kinetics of the reaction. An estimate of the upper limit of the free chloride concentration in the uncatalyzed system was made from the results of the chloride catalyzed exchange study.This estimate, rv10-8g-ion/liter for the free chloride ion concentration, suggests that neither sulfur monochloride nor thionyl chloride undergoes a significant degree of self-ionization. The effect of the Lewis acid antimony(V) chloride on the rate of radiochlorine exchange between sulfur monochloride and thionyl chloride has been studied.The presence of low concentrations of antimony(V) chloride exerts a pronounced catalytic effect on the rate of the radiochlorine exchange through a broad concentration range. The antimony(V) catalyzed exchange reaction, in excess thionyl chlor- ide, appeared to be first order with respect to sulfur monochloride and three-halves order with respect to antimony(V) chloride. How- ever, the high degree of irreproducibility in the exchange rates pre- vents the postulation of a truly meaningful rate law.The apparent Arrhenius energy of activation for the antimony(V) catalyzed radio- chlorine exchange between sulfur monochloride and thionyl chloride was 10.0 ± 0.4 kcal/mole in excess thionyl chloride. Meaningful kinetics data for the antimony(V) chloride catalyzed exchange could not be obtained in excess sulfur monochloride due to the fact that it was not found possible to determine accurately the concentration of antimony in such systems. Antimony(V) chloride was found to be catalytically less effec- tive than chloride ion by a factor of approximately 500. The results of the antimony(V) chloride catalyzed exchange of radiochlorine between sulfur monochloride and thionyl chloride indi- cate the dependence of the exchange rate on all three components and would appear to suggest a molecular rather than an ionic process and to imply the involvement of all three reactant species in the activated complex. Equilibrium and Exchange Rate Studies in Sulfur Monochioride, Thionyl Chloride and Related Systems by Samuel Clemmer Dalton A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy June 1970 APPROVED: Redacted for Privacy Professor of Chemistry in charge of major Redacted for Privacy Chairman of 5-e'ptr nent osr-CITemi stry Redacted for Privacy Dean of Graduate School Date thesis is presented October 3, 1969 Typed by Opal Grossnicklaus for Samuel Clemmer Dalton ACKNOWLEDGMENT The author wishes to express his sincere appreciation to Professor T. H. Norris for his guidance, friendship and patience during the course of this investigation. To my wife, Judie, and my mother, Lenore, goes my deepest appreciation for their understanding and encouragement throughout this work. This investigation was sponsored by the United States Atomic Energy Commission under contract AT(45-1)-244 between the com- mission and Oregon State University. In addition I would like to thank the Weyerhaeuser Company Foundation for the support provided by the Weyerhaeuser Fellowship during 1968-1969. DEDICATION To the women in my life, Judie and Lenore TABLE OF CONTENTS I. INTRODUCTION 1 II.PHASE DIAGRAM OF THE SULFUR MONOCHLORIDE- TETRAETHYLAMMCNIUM CHLORIDE SYSTEM 24 A.Introduction 24 B.Experimental 26 1. Thermal analysis technique 26 a.Melting point cell 29 b.Temperature transducer 32 c.Thermocouple calibration 32 d.Sample preparation 35 e.Procedure 36 f. Interpretation of cooling and warming curves 38 g.Reproducibility and accuracy check 41 h. Experimental data 44 2.Phase volume technique 44 a.Introduction 44 b.Sample preparation--phase volume technique 47 c.Temperature control and phase volume measurement 48 d.Experimental data 50 3.Static visual method 50 4.Analysis of solid phase in region NTEAC =0.25 to 0.50 54 C.Results and Discussion 59 1. Description of the phase behavior of the sulfur monochloride -- tetraethylammonium chloride system 59 2.Discussion of other investigations of the sulfur monochloride- -tetraethylammonium chloride system 65 3.Discussion of related phase systems and specu- lations regarding the nature of the present system 68 4.Conclusion 84 III. PRESSURE--COMPOSITION STUDIES OF BINARY SYSTEMS OF SULFUR DIOXIDE, SULFUR MONOCHLORIDE OR THI- ONYL CHLORIDE WITH TETRAETHYL- OR TETRAMETHYL- AMMONIUM CHLORIDE 85 A. Introduction 85 B.Experimental 93 TABLE OF CONTENTS (CONTINUED) 1. Introduction to the pressure- -composition technique 93 2.Manometer and sample systems 95 3.Purification and treatment of materials 97 4.Sample preparation 97 5.Temperature control 98 6.Vapor pressure measurement 100 7.Calculation of the enthalpy of dissociation of adducts 103 Preparation and analysis of (CH) NC1° SOC1 8. 254 2 and 2( C2 H5 )NC1 SO2 104 4 9.Melting point determinations 107 C.Results and discussion 126 1. The system, thionyl chloride-- tetraethyl- ammonium chloride 126 2.The system, thionyl chloride--tetramethyl- ammonium chloride 129 3.The system, sulfur dioxide- tetraethylammon- ium chloride 130 4.The system, sulfur dioxide- tetramethyl- ammonium chloride 132 5.The system, sulfur monochloride--tetraethyl- ammonium chloride 133 D.Conclusions 134 IV. SPECTROPHOTOMETRIC OBSERVATIONS OF SYSTEMS CONTAINING SULFUR MONOCHLORIDE, THIONYL CHLOR- IDE AND TETRAETHYLAMMONIUM CHLORIDE 139 A.Introduction 139 B.Experimental 142 1. Introduction 142 2.Experimental tec haiques used in preliminary observations 143 3.Determination of amount and source of water contamination in preliminary work 145 4.Acetonitrile drying procedure and preparation of stock salt solution 147 5.Ultraviolet spectra sample preparation and observation 149 6.Infrared spectra sample preparation and observation 155 TABLE OF CONTENTS (CONTINUED) 7.Preparation and analysis of the adduct (CH ) NC'. SOC12 157 254 C.Results and discussion 158 1. The system, sulfur monochloride- -tetraethyl- ammonium chloride. 2.The system, thionyl chloride--tetraethyl- ammonium chloride 16.% D.Conclusions 187 V.RADIOCHLORINE EXCHANGE BETWEEN SULFUR MONOCHLORIDE AND THIONYL CHLORIDE 189 A. Introduction 189 B.Experimental techniques and data 192 1.General 19.2 2.Radioactivity assay and counting techniques 195 3.Chemical analysis