ELECTROCHEMISTRY OF ORGANIC COMPOUNDS BY DE. WALTPIER LOB Privatdocent in the University of Bonn AUTHORIZED TRANSLATION FROM THE AUTHOR'S ENLARGED AND REVISED THIRD EDITION OF ELECTROLYSIS AND ELECTROSYNTHESIS OF ORGANIC COMPOUNDS BY H. W. F. LOKENZ, A.M., PH.D. Gradiiate of the University of Berlin Formerly Instructor of Organic Chemistry in the University of Pennsylvania Translator of Lasxar-Gohn' , ii "UHnary Analysis,'''' etc. WITH TEN ILLUSTRATIONS FIRST EDITION FIRST THOUSAHD NEW YORK JOHN WILEY & SONS LONDON: CHAPMAN" & HALL, LIMITED 1906 Copyright, 1905 Br H. W. F. LOREKZ EOBEHT DSUMMOND, PRINTJEE, KBW YORK AUTHOR'S PREFACE TO THE THIRD GERMAN EDITION. THE great progress which the electrochemistry of organic compounds has made in the past few years rendered it desirable to rearrange the whole material, and to express by a suitable title the extension of the task which the book seeks to fulfil. The theoretical discussions which form an introduction to the experimental part of electrolysis are of a subjective, par- tially hypothetical character, that the present state of our knowledge of the mechanism of the electrical reaction cannot prevent from being otherwise. But the given ideas have proved trustworthy as aids in directing and arranging my experimental work; perhaps they will be equally serviceable to others, not- withstanding the possibility and justifiability of divergent views. The object of the work has remained the same in the new as in the old form: to give a connected survey of what has been done, and to incite to further efforts in investigations, I desire here to express my thanks to Dr. E. Goecke who helped me in looking over the literature on the subject. The second English edition, corresponding to the present German edition, will appear shortly. WALTHER LOB. BONN, April, 1905. iii TRANSLATOR'S PREFACE TO SECOND AMERICAN EDITION. A NEW edition of Doctor Lob's book on this interesting and important subject has become necessary, because of the great increase in the past few years in the quantity of new experimental material. The author has happily met this requirement in his present excellent work on the " Electro- chemistry of Organic Compounds." Doctor Lob has spared no pains to bring the subject-matter strictly up to date, and has entirely rewritten and rearranged the material so as to present it in the best possible form. Two special chapters have been arranged, devoted to a more thorough discussion of the theoretics and methodics of organic electrochemistry, and also a chapter on electric en- dosmose. The whole of Part II, on electrothermic processes and the silent electric discharge, is new. Complying with the wish of the author in this as in the first translation, the original text has been followed by the translator as closely as possible. It is hoped that this new edition will meet with the same cordial reception accorded the earlier one. SPRINGFIELD, OHIO, October, 1905. v CONTENTS. PAGB INTRODUCTION 1 PART L ELECTROLYTIC PROCESSES. CHAPTER I. THEORETICS 5 1. Forms of Reaction 5 2. Properties of Electrolytic Processes io 3. Significance of the Velocity of Reaction IX 4. Reaction "Velocity and Specific Effect of Reducers and Oxidizers. 13 5. Electrode Potential and Reaction Mechanism 14 6. Electrode Processes 18 A. Cathodic Processes 18 a. Unattackable and Attackable Cathodes 18 b. Excess Potential and the Reduction Action. . 20 c. Concerning Substances Reducible with Difficulty 23 B. Anodic Processes 27 7. Theory of the Reaction Velocity in Electrolytic Processes 30 a. Diffusion Theory. 30 b. Osmotic Theory of Electrical Reduction 34 c. Summary of the Theories 37 CHAPTER II. METHODICS • • 40 1. The Cells 40 2. Arrangement of Experiments and Measurements of Potential 44 3. The Electrodes 51 vii viii CONTENTS. CHAPTER III. PAGE ELECTROLYSIS OF ALIPHATIC COMPOUNDS ,. 54 1. Carbon and Hydrocarbons 54 2. Nitro-derivatives of Hydrocarbons 56 3. Hydroxyl Compounds 57 4. Derivatives of the Alcohols 65 5. Aldehydes, Ketones, and their Derivatives 66 a. Aldehydes 66 6. Ketones 69 6. Acids 75 I. Monobasic Acids, C 7t H 2Tl 0 2 77 II. Monobasic Alcohol- and Ketonic Acids 95 ' a. Alcohol-acids 95 b. Ketonic Acids 99 III. Dibasic Acids .» 102 IV. Unsaturated Dibasic Acids 115 V. Polybasic Acids 116 7. Amines, Acid Amides, Imides and Nitriles 118 8. Carbonic-acid Derivatives 121 9. Sulphur Derivatives of Carbonic Acid 130 CHAPTER IV. ELECTROLYSIS OF AROMATIC COMPOUNDS 132 1. Hydrocarbons , 133 2. Nitro- and Nitroso-compounds 135 a. General Observations on the Heduction of Nitro-Com- pounds 136 b. Reduction of Nitrobenzene 145 I. Chemical Relations 145 II, Significance of the Electrical Relations 149 III. Presentation of the Reduction Phases of Nitrobenzene 154 c. Substitution Products of Nitrobenzene 103 I. General Laws Governing Substitution 103 II. Homologues of Nitrobenzene 168 III. Halogen Derivatives of Mononitro-bodies 174 IV. Nitrophenols 175 V. Nitranilines 177 VI. Nitro-derivatives of Diphenylamine and of Amidotri- phenylmethane 180 VII. Nitroaldehydes and Nitroketones 181 VIII. Nitrobenzene-carboxylic Acids , 183 IX. Nitrobenzene-sulphonic Acids 186 X. Further Reductions of Nitro-bodies igg CONTENTS. ix PAGE XI. Nitro-derivatives of the Naphthalene-, Anthracene-, and Phenanthrene Series 190 XII. Nitroso- and Nitro-derivatives of the Pyridine and Quinoline Series 192 3. Amido-derivatives 193 4. Phenols 199 5. Alcohols, Aldehydes, Ketones, Quinones 202 6. Acids ' 211 7. Acid Amides and Nitriles 215 8. The Reduction of Indigo 216 9. Pyridine Derivatives and Alkaloids 217 10. The Camphor Group 225 11. Electrolysis of Blood and Albumen 229 CHAPTER V. ELECTROLYSIS WITH ALTERNATING CURRENTS 230 CHAPTER VI ELECTRIC ENDOSMOSE 233 PART II. ELECTROTHERMIC PROCESSES AND THE SILENT ELECTRIC DISCHARGE. CHAPTER I. THEORETICS AND METHODICS 235 1. Theoretics 235 2. The Reaction Temperatures 238 3. Arrangements 241 CHAPTER II. THE SPARK DISCHARGE AND THE VOLTAIC ARC. 244 1, The Spark Discharge 244 2. The Voltaic Arc 249 CHAPTER III THE UTILIZATION OF CURRENT HEAT IN SOLID CONDUCTORS 252 x CONTENTS. CHAPTER IV. PAGE THE SILENT ELECTRIC DISCHARGE AND THE EFFECT OF TESIA-CURRENTS . 261 1. The Silent Electric Discharge 261 a. Arrangements 263 b. Chemical Kesults 265 I. Carbonic Acid and Carbon Monoxide 266 II. Hydrocarbons 270 III. Alcohols 273 IV. Aldehydes and Ketones 276 V. Acids and Esters 277 VI. 1. Concerning the Binding of Nitrogen to Organic Sub- stances 279 2. Behavior of Vapors towards Tesia-currents 288 LIST OF AUTHORS , 293 INDEX 297 ELECTROCHEMISTRY OF ORGANIC COMPOUNDS. INTRODUCTION. CHARACTERISTICS AND CLASSIFICATION OF THE SUBJECT-MATTER. THE application of electrical energy for effecting organic reactions was tried long ago and in the most various ways. The observations, however, w T ere at first few in number, leading points of view were lacking, and the results were incoherent and often contradictory. A definite start in attacking the many problems which are presented by organic chemistry was not made until larger electrical equipments were introduced into scientific and technical enterprises- For about a decade organic electrochemistry has been undergoing a quiet but steady development. Electrical energy can be employed directly or indirectly for accomplishing chemical reactions—directly, if the field traversed by the current is of an electrolytic nature; indirectly, if a transformation of electrical energy into other forms takes place, which—for instance, heat or light—can bring about chemical phenomena outside of the current field. Both utilizable forms of electricity are of theoretical and practical importance; the former in electrolysis, particularly in reduction, oxidation 2 ELECTROCHEMISTRY OF ORGANIC COMPOUNDS. and substitution reactions, the latter in pyrogenic and photo- chemical processes. Another kind of electrochemical action, and one in which the connection between electrical work and chemical effect is still hidden in obscurity, is the glow ; or silent discharge. In spite of the few facts known about this form of electrical energy, it can be claimed positively that it is of fundamental importance in the synthesis of simple organic bodies and is, perhaps, a means for explaining the methods which living nature employs in building up substances. A survey of the great number of organic electrochemical investigations shows a very unequal distribution of scientific labor among the separate parts of the extensive domain. The electrolytic reactions have been by far most thoroughly investi- gated, particularly the reduction processes. Oxidation and substitution reactions have more rarely been the subject of successful researches. Pyrogenic decompositions and syntheses of organic substances produced by the induction spark, the electric arc, or highly heated conductors of the first class have been numerously mentioned. However, we are just beginning to obtain scientific- results in this line of work. It has already been mentioned that our knowledge of the action of the glow and convective discharge on carbon compounds is extremely insignificant. The varied properties of organic bodies explain this unequal treatment and the result. The reduction of carbon compounds occurs usually at certain reducible groups in the molecule with- out destroying this latter. The whole molecule is usually exposed to the action of the electrolytic oxygen. The final product of a reduction is closely related chemically to the material started out with; the end result of an oxidation is often the complete combustion of the molecule. Quite a number of possibilities exist between a slight attack by oxygen upon and the complete destruction of a compound by oxidation. A realization of these, if at all possible, depends upon most painstaking observa- tions of fixed experimental conditions, which are often difficult to determine. Hence oxidation processes are much more com- [...]... addition of oxygen, or both, it is called oxidation Examples of such oxidations are the conversion of hydrazobenzene into azobenzene: C6H5NH - NH - C6H5 + O - C6H5N « NC6HS + H 2 0 ; the conversion of benzene into hydroquinone by a direct addition of oxygen: C6He-f2 0-C6H 4 (OH) 2 ; the production of nitrobenzoic acid from nitrotoluene by the addition of oxygen and withdrawal of hydrogen: N02C6H4CH3 + 3 O-NQ... electrolysis O ELECTROCHEMISTRY OF ORGANIC COMPOUNDS The reduction of nitrobenzene to nitrosoben^ene furnishes an example of deoxidation: C 6 H 5 N0 2 +2H ~ CGH5NO + H2(X In the conversion of azobenzene to hydrozobenzene an addition of hydrogen takes place: C6H5N « NC 6 H S +2H - C 6 H 5 NH - NHC6H5, A withdrawal of oxygen and addition of hydrogen occurs simultaneously in the reduction of nitrobenzene... another after their discharge Thus either a union of several anions occurs or, far oftener, more complicated transpositions and decompositions accompany these reactions 5 6 ELECTROCHEMISTRY OF ORGANIC COMPOUNDS An example of the first kind of decomposition is furnished by the electrolysis of potassium xanthate l : 2 C2H5OCSSK-2 C2H5OCSS'+2 K \ 2 CsHsOCSS-CsHsOCSS-SSCOCsHs In this case two anions unite to... mercury 0-0 05 volt ll 0.09 0.21 " 0.23 " rf 0.53 0.64 iC 0.70 " 0.78 " Nernst, who introduced the conception of excess potential into the science of electrochemistry, accepts as the cause of these phenomena the varying solubility of hydrogen in the metals l Ztschr I phys Chem 30, 89 (1899V 22 ELECTROCHEMISTRY OF ORGANIC COMPOUNDS Since the energy of reduction depends chiefly upon the height of the cathode... (1904) 2 24 ELECTROCHEMISTRY OF ORGANIC COMPOUNDS in explaining the phenomena occurring here, and we may possibly get along with a uniform interpretation The deciding importance of reaction, velocities on the course of every chemical action requires of us a clear explanation of the relation of the influences cooperating in the course of the reaction to that fundamental factor, the velocity of reaction... forces of affinity specific of the single elements or compounds and characteristic of the reacting masses In the majority of the electrolyses of organic bodies the circumstances are very much simplified by the fact that it is only a question of two different forms of reaction, viz reduction and oxidation The limits within which a reduction can take place at all are already given in the case of a cathodic... size regulates the number of the ions discharged in a unit of time at a given electrode surface, hence regulating its concentration; secondarily, the reactions of the ions with one another and with the depolarizer For variations in the concentration of the value 18 ELECTROCHEMISTRY OF ORGANIC COMPOUNDS c\ occur through both processes and, since the velocity of the reaction of the discharged ions with... of the reversible hydrogen evolution by a, and the value of the excess potential by e7 then the electrical work in the separation of a gram-equivalent of gaseous hydrogen in the first case is A =96540a; and in the second Ai-96540(a-he) Since the total work in both cases must be equal, there results, if, as assumed, a production of a quantity of heat q occurs, the equation 96540a = 96540 ( a + e ) -. .. disposition of each of the three resulting chapters * ELECTROCHEMISTRY OF ORGANIC COMPOUNDS- It may be remarked, particularly in regard to the description of the methods, that only the necessary and important data are mentioned here The author does not intend to give a practical guide for making experiments Only original investigations or special text-books x can serve such a purpose It is the object of the... determinatively influenced by these concentrations The importance of the reaction velocity is especially fundamen- 12 ELECTROCHEMISTRY OP ORGANIC COMPOUNDS tal for the course of the reaction; for in the majority of cases it is a case of processes vying with one another, the reaction velocities of which determine the preponderance, and hence the result, of the one or the other process The last remark, that competitive . Lasxar-Gohn' , ii "UHnary Analysis,'''' etc. WITH TEN ILLUSTRATIONS FIRST EDITION FIRST THOUSAHD NEW YORK JOHN WILEY & SONS LONDON: CHAPMAN" &. Concerning the Binding of Nitrogen to Organic Sub- stances 279 2. Behavior of Vapors towards Tesia-currents 288 LIST OF AUTHORS , 293 INDEX 297 ELECTROCHEMISTRY OF ORGANIC COMPOUNDS. INTRODUCTION Further Reductions of Nitro-bodies igg CONTENTS. ix PAGE XI. Nitro-derivatives of the Naphthalene-, Anthracene-, and Phenanthrene Series 190 XII. Nitroso- and Nitro-derivatives of the Pyridine