Viewed the Entropy Problem Associated with the Structure of Dinitro
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A STUDY OP SO MIL PHYSICAL AMD CHEMICAL PROPERTIES OP THE BINARY SYSTEM DINITROGEN TETR0XIDE-1,4-DI0XANE DISSERTATION Presented in partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Harry Wilson Ling, A.B. The Ohio State university 1954 i ACKNOWLEDGEMENTS The author wishes to express appreciation to Dr. Harry H. Sisler for suggesting this research and for his continued personal interest and guidance throughout the course of the investigation. Appreciation is also extended to E. D. Loughran for his cooperation in the use of the Perkin-Elmer infrared spectrophotometer, and to Dr. William J. Taylor for contributing to the discussion of the structure of the dioxane-dinitrogen tetroxide complex. The assistance of the Ordnance corps, U. S. Army, through a contract with The Ohio state University Research Foundation, and of the Standard oil Company (Indiana), through fellowship funds, are gratefully acknowledged. ii TABLE OP CONTENTS Page ACKNOWLEDGEMENTS i LIST OP FIGURES iv LIST OP TABLES v I. INTRODUCTION 1 II. HISTORICAL a. physical Properties of Dinitrogen Tetroxide 2 b. structure of Dinitrogen Tetroxide 3 c. Molecular Addition Compounds of Dinitrogen Tetroxide 11 III. VISCOSITY STUDY IN THE SYSTEM DINITROGEN TETROXIDE-1,4-DIOXANE a. Introduction 23 b. purification of Materials 30 c. Experimental Procedure 31 d. Results 36 e. Discussion and Conclusions 40 IV. CRYOSCOPIC STUDY OP SOLUTIONS OP DINITROGEN TETROXIDE IN 1,4-DIOXANE a. introduction 41 b. purification of Materials 44 c. Experimental Procedure 45 d. Results 51 e. Discussion and Conclusions 53 iii Page V. STUDY OF THE SYSTEM DINITROGEN TETROXIDE 1,4-DIOXANE IN THE GAS PHASE a. Introduction 56 b* Experimental Procedure 59 c. Results 65 d. Discussion and Conclusions 76 VI. SUMMARY AND DISCUSSION 78 BIBLIOGRAPHY 8 6 AUTOBIOGRAPHY 91 I iv LIST OF FIGURES Figure Page 1. Dinitrogen Tetroxide purification Apparatus 32 2. Dinitrogen Tetroxide Transfer Cell 33 3. viscosity Apparatus 35 4. Density-Composition Diagram of Binary System 38 5. Viscosity-composition Diagram of Binary System 39 6 . Freezing point Apparatus 46 7. Typical Cooling Curve 50 8 . Cryoscopic Data; X-Composition Diagram 55 9. Colorimetric Apparatus for Gas phase Study 60 10. Dioxane Gas Infrared Absorption Cell 64 11. Infrared Absorption Spectrum of Gaseous 1,4-Dioxane 6 6 12. Infrared Absorption Spectrum of Gaseous Dinitrogen Tetroxide • 67 13. Infrared Absorption Spectrum of the Combined Gases 6 8 v LIST OF TABLES Table Page I. Viscosity Study in the System Dinitrogen Tetroxide-1,4-Dioxane 57 II. Cryoscopic Constant of 1,4-Dioxane 52 III. Cryoscopic Measurements of Solutions of Dinitrogen Tetroxide in Excess 1,4-Dioxane 54 IV. Calibration of Electrophotometer 65 v. Colorimetric Study of the Gas phase System Dinitrogen Tetroxide-1,4-Dioxane 70 VI. Qualitative Observation of the Gas phase System Dinitrogen Tetroxide-1,4-Dioxane 71 VII. Infrared Absorption Study of the Gas phase System Dinitrogen Tetroxide-1,4-Dioxane 72 1 A STUDY OF SOME PHYSICAL AND CHEMICAL PROPERTIES OF THE BINARY SYSTEM DINITROGEN TETROXIDE-1,4-DIOXANE I. INTRODUCTION Recently Rubin, Sisler and Shechter^ established that dinitrogen tetroxide is capable of forming addition compounds with certain ethers. This was accomplished by making phase studies of the binary dinitrogen tetroxide- ether systems. The addition compounds formed In the systems investigated were shown to be complexes of N2 O4 molecules by magnetic and spectroscopic analysis. Of the several addition compounds observed it was noted that the 1:1 addition compound formed between 1,4-dioxane and dinitrogen tetroxide was quite different from the others in its higher stability and relatively high melting point. A bicyclic monomer, a dimer, and a polymeric aggre gation were proposed as possible structures for the dinitrogen tetroxide-1 ,4-dioxane addition compound. In the case of the bicyclic structure the relatively high melting point of the compound may be explained by analogy with a number of other compounds which also have unusually high melting points, e.g. camphor. in the case of the polymeric aggregation the relatively high melting point of the compound may be explained as resulting from its high molecular weight. With the hope of obtaining information which would assist in resolving this question of structure the authors proposed (1 ) to investigate the viscosity of various 1,4-dioxane-dinitrogen tetroxide liquid mixtures, and (2 ) to determine the molecular weight of the addition compound using the cryoscopic method. Since the existence of the addition compound between 1 ,4-dioxane and dinitrogen tetroxide has been established in the solid and liquid states, it was proposed, as a logical extension of these facts, to study gaseous mix tures of the two components to investigate the possibility of association in the vapor phase. II. HISTORICAL a. Physical properties of Dinitrogen Tetroxide The dinitrogen tetroxide-nitrogen dioxide equilibrium N 2 0 4 2 n 0 2 has long been recognized. At temperatures well below the melting point of dinitrogen tetroxide the equilibrium is shifted almost entirely to the left as indicated by the Q formation of colorless crystals. At -11.2°c. , the melting point of dinitrogen tetroxide, the slight yellow color present indicates that some dissociation has taken place and nitrogen dioxide is present. At the boiling 2 point 21.15°C. t the vapor is dissociated to the extent of about 16 per cent2 and is deep reddish-brown in color. On heating above the boiling point the color of the vapor darkens, the color change being accompanied by a decrease in vapor density to 140°C. At 140°C. the density corres ponds to molecular nitrogen dioxide. As the vapor is heated above this temperature the density decreases and the color becomes paler owing to the dissociation 2N0g ^"'" — 2N0 + 02 until at 62o°C. the gas is colorless and dissociation into nitric oxide and oxygen is essentially complete'"’. According to vapor density measurements the dissociation of dinitrogen tetroxide into nitrogen dioxide at various temperatures ( 1 atmosphere pressure) is as follows^. Temp.°C. 21.9 26.7 6 0 . 2 100.1 135.0 140.0 % Dissoc. 15.7 20.1 52.8 89.3 99.1 '"**100.0 The equilibrium constant for the dinitrogen tetroxide-nitrogen dioxide equilibrium has been measured by Verhoek and Daniels^ at several temperatures. The idealized equilibrium constants (Kp) extrapolated to zero pressure are 0.1426 atmospheres at 25°C., 0.3183 atmos pheres at 35°C. and 0.6706 atmospheres at 45°C. b. The Structure of Dinitrogen Tetroxide The structure of the dinitrogen tetroxide molecule has been the subject of much controversy. Several structures have been proposed. A typical resonance form for each structure is shown below* 0=N-0-0-N“0 i tt I II III la IV Ilia la and Ilia are the older representations of modern structures I and III. Structures I, III and their older counterparts have received considerable support whereas structure II was never considered very seriously because of the peroxide linkage. The initial approach to the determination of the structure of the dinitrogen tetroxide molecule was through chemical evidence obtained from various reactions of Mellor5 has summarized the early chemical evidence which seems to favor structure Ilia. Mellor pointed out that Exner® favored Ilia because of the reaction of nitryl chloride and silver, nitrite to produce dinitrogen tetroxide and silver chloride, and also because dinitrogen tetroxide reacts with water to form nitrous and nitric acids NOo I J D ----- >HONO ■+• HONOp i r ~ p~' j N O ______ Henryk reported the production of alkyl nitrates from alkyl halides, a fact which supports structure Ilia. Further chemical support for this structure comes from the reaction® of potassium nitrate and nitrosyl sulfuric acid to form dinitrogen tetroxide and potassium hydrogen sulfate, and from the formation® of diazobenzene nitrate from aniline. Nitrosyl sulfuric acid also reacts® with sodium chloride or sodium bromide with production of nitrosyl chloride or nitrosyl bromide, respectively. Houston and Johnson-**®, In their summary of evidence for structure Ilia, indicate the presence of a nitroso group from the reaction of N-methylaniline to give N-methyl-N-nitroso-p nitroaniline. They point out that dinitrogen tetroxide reacts with water to produce nitrous and nitric acid which contain nitrogen of different oxidation state. Hence, it must be that these two atoms are of dissimilar oxidation state in the original molecule. Otherwise, It would have to be supposed that mutual oxidation and reduction have taken place between these two nitrogens. Regarding this possibility of mutual oxidation and reduction, structure la shows both nitrogens as having an oxidation state of five whereas in structure II, both are assigned an oxidation state of three. In either of these cases one atom would have to retain its original oxidation state and the other change on reaction with water. The primary reaction of dimethyl or diethyl malonate is explicable on the basis of structure Ilia. When dinitrogen tetroxide is distilled into aniline, ortho-, meta- or para- nitroaniline in anhydrous benzene, diazonium nitrates are formed along with diazo-amido- benzenes. The unusual behavior of dinitrogen tetroxide towards mercury diphenyl**"*- is easily explained by the nitrosyl nitrate structure. Pauling-*-^ suggested that structure I should be less stable than structure III primarily on the basis of the adjacent charge rule. Meyer**-® considered that structure II is consistent with the combination of amylene and dinitrogen tetroxide to form a substance of formula C^H^o(NOg)2 • Reduction of this compound gives ammonia and not the diamine indicating carbon to oxygen attachments rather than carbon to nitrogen. However this work was later shown to be in erro Sudborough and Millar**-8 considered nitrogen dioxide as the oxide of nitrosyl, corresponding'to nitrosyl chloride.