Electrochemistry in Nonaqueous Solutions. Kosuke Izutsu Copyright © 2002 Wiley-VCH Verlag GmbH & Co. KGaA ISBNs: 3-527-30516-5 (Hardback); 3-527-60065-5 (Electronic) Kosuke Izutsu Electrochemistry in Nonaqueous Solutions Electrochemistry in Nonaqueous Solutions. Kosuke Izutsu Copyright © 2002 Wiley-VCH Verlag GmbH & Co. KGaA ISBNs: 3-527-30516-5 (Hardback); 3-527-60065-5 (Electronic) Related Titles from WILEY-VCH Bard, A.J., Stratmann, M., Licht, S. (Eds) Encyclopedia of Electrochemistry, Volume VI 2001. ISBN 3-527-30398-7 Kaifer, A.E., Gómez-Kaifer, M. Supramolecular Electrochemistry 1999. ISBN 3-527-29597-6 Memming, R. Semiconductor Electrochemistry 2000. ISBN 3-527-30147-X Günzler, H., Williams, A. (Eds) Handbook of Analytical Techniques 2001. ISBN 3-527-30165-8 Electrochemistry in Nonaqueous Solutions. Kosuke Izutsu Copyright © 2002 Wiley-VCH Verlag GmbH & Co. KGaA ISBNs: 3-527-30516-5 (Hardback); 3-527-60065-5 (Electronic) K. Izutsu Electrochemistry in Nonaqueous Solutions Electrochemistry in Nonaqueous Solutions. Kosuke Izutsu Copyright © 2002 Wiley-VCH Verlag GmbH & Co. KGaA ISBNs: 3-527-30516-5 (Hardback); 3-527-60065-5 (Electronic) Professor Dr. K. Izutsu n This book was carefully produced. Nevertheless, 3-8-23 Motomachi author and publisher do not warrant the informa- Matsumoto 390-0803 tion contained therein to be free of errors. Rea- Japan ders are advised to keep in mind that statements, data, illustrations, procedural details or other items may inadvertently be inaccurate. Library of Congress Card No.: applied for British Library Cataloguing-in-Publication Data: A catalogue record for this book is available from the British Library. Die Deutsche Bibliothek – CIP-Cataloguing-in- Publication Data A catalogue record for this publication is available from Die Deutsche Bibliothek. © WILEY-VCH Verlag GmbH D-69469 Weinheim, 2002 All rights reserved (including those of translation in other languages). No part of this book may be reproduced in any form – by photoprinting, mi- crofilm, or any other means – nor transmitted or translated into machine language without written permission from the publishers. Registered names, trademarks, etc. used in this book, even when not specifically marked as such, are not to be considered unprotected by law. Typesetting K+V Fotosatz GmbH, Beerfelden Printing betz-druck gmbh, Darmstadt Bookbinding J. Schäffer GmbH & Co. KG, Grünstadt printed in the Federal Republic of Germany printed on acid-free paper ISBN 3-527-30516-5 Electrochemistry in Nonaqueous Solutions. Kosuke Izutsu V Copyright © 2002 Wiley-VCH Verlag GmbH & Co. KGaA ISBNs: 3-527-30516-5 (Hardback); 3-527-60065-5 (Electronic) Preface A majority of chemical reactions are carried out in solution. The use of a solvent as reaction medium makes it easy to control reaction conditions such as tempera- ture, pressure, pH, rate of mass transfer, and concentration of reactant. Water is the most popular solvent. However, by using appropriate non-aqueous solvents, substances that are insoluble in water can be dissolved, substances that are un- stable in water remain stable, and chemical reactions that are impossible in water become possible. The reaction environments are markedly wider in non-aqueous solvents than in water. The widespread use of non-aqueous solvents, especially dipolar aprotic solvents, began in the 1950s in various fields of pure and applied chemistry and has con- tributed greatly to later advances in chemical sciences and technologies. From the very beginning, electrochemistry in non-aqueous solutions has played an impor- tant role in exploring new chemical possibilities as well as in providing the meth- ods to evaluate static solvent effects on various chemical processes. Moreover, many new electrochemical technologies have been developed using non-aqueous solvents. Recently, electrochemistry in non-aqueous solutions has made enormous progress: the dynamic solvent effects on electrochemical processes have been greatly elucidated and solvent effects are now understood much better than be- fore. On the other hand, however, it is also true that some useful solvents have properties that are problematic to human health and the environment. Today, ef- forts are being made, under the framework of ‘green chemistry’, to find environ- mentally benign media for chemical processes, including harmless non-aqueous solvents, immobilized solvents, ionic liquids, supercritical fluids, aqueous sys- tems, and even solventless reaction systems. For electrochemical purposes, replac- ing hazardous solvents by harmless solvents, ionic liquids and supercritical fluids appears to be promising. This book was written to provide readers with some knowledge of electrochem- istry in non-aqueous solutions, from its fundamentals to the latest developments, including the current situation concerning hazardous solvents. The book is di- vided into two parts. Part I (Chapters 1 to 4) contains a discussion of solvent prop- erties and then deals with solvent effects on chemical processes such as ion solva- tion, ion complexation, electrolyte dissociation, acid-base reactions and redox reac- tions. Such solvent effects are of fundamental importance in understanding chem- VI Preface istry in non-aqueous solutions; furthermore, their quantitative evaluations are of- ten carried out by means of electrochemical techniques. Part II (Chapters 5 to 12) mainly deals with the use of electrochemical techniques in non-aqueous solu- tions. In Chapter 5, the fundamentals of various electrochemical techniques are outlined in preparation for the following chapters. In Chapters 6 to 9, the applica- tions of potentiometry, conductimetry, polarography, voltammetry, and other new electrochemical techniques in non-aqueous solutions are discussed by focusing on the chemical information they provide. Chapters 10 and 11 examine methods of selecting and purifying the solvents and electrolytes of electrochemical impor- tance. Finally, in Chapter 12, some practical applications of non-aqueous solvents in modern electrochemical technologies are discussed. These include their use in batteries, capacitors and display devices, and such processes as electrolytic refin- ing, plating, synthesis and polymerization. The applicability of ionic liquids and supercritical fluids as environmentally benign media for electrochemical technol- ogy is also dealt with. Most chemists are familiar with chemistry in aqueous solutions. However, the common sense in aqueous solutions is not always valid in non-aqueous solutions. This is also true for electrochemical measurements. Thus, in this book, special emphasis is placed on showing which aspects of chemistry in non-aqueous solu- tions are different from chemistry in aqueous solutions. Emphasis is also placed on showing the differences between electrochemical measurements in non-aque- ous systems and those in aqueous systems. The importance of electrochemistry in non-aqueous solutions is now widely recognized by non-electrochemical scientists – for example, organic and inorganic chemists often use cyclic voltammetry in aprotic solvents in order to determine redox properties, electronic states, and reac- tivities of electroactive species, including unstable intermediates. This book will therefore also be of use to such non-electrochemical scientists. I obtained most of the information included in this book from the publications of many scientists in this field. I would like to express my sincere thanks to all of them. I also would like to thank my coworkers for their cooperation, the editorial and production staff of Wiley-VCH for their help and support, and my wife for her assistance and patience. Matsumoto, December 2001 Kosuke Izutso Books, reviews and data compilations relating to non-aqueous solution chemistry and/or non-aqueous solvents: 1 Lagowski, J.J. (Ed.) The Chemistry of 3 Bard, A.J. (Ed.) Electroanalytical Chemis- Non-Aqueous Solvents, Academic Press, try, Marcel Dekker, New York, Vol. 3, New York, Vol. 1, 1966; Vol. 2, 1967; Vol. 1969, p. 57; Vol. 8, 1975, p. 281, etc. 3, 1970; Vol. 4, 1976; Vol. 5A, 1978; Vol. 4 Coetzee, J.F., Ritchie, C.D. (Eds) So- 5B, 1978. Includes many reviews. lute-Solvent Interactions, Marcel Dekker, 2 Charlot, G., Trémillon, B. Chemical New York, Vol. I, 1969; Vol. II, 1976. In- Reactions in Solvents and Melts, Pergamon cludes reviews. Press, Oxford, 1969. Preface VII 5 Mann, C.K., Barnes, K.K. Electrochemi- 18 Burger, K. Solvation, Ionic and Complex cal Reactions in Nonaqueous Solvents, Mar- Formation Reactions in Nonaqueous Sol- cel Dekker, New York, 1970. vents, Elsevier, Amsterdam, 1983. 6 Janz, G.J., Tomkins, R.P. T. (Eds) Non- 19 Marcus, Y. Ion Solvation, Wiley & Sons, aqueous Electrolytes Handbook, Academic New York, 1985. Includes large amounts Press, New York, Vol. 1, 1972; Vol. 2, of data. 1973. 20 Riddick, A., Bunger, W.R., Sakano, 7 Covington, A.K., Dickinson, T. (Eds) T. K. Organic Solvents, Physical Properties Physical Chemistry in Organic Solvent Sys- and Methods of Purification, 4th edn, Wi- tems, Plenum Press, New York, 1973. In- ley & Sons, New York, 1986. Includes de- cludes reviews and data compilations. tailed data on solvent properties and 8 Fritz, J.S. Acid-Base Titrations in Non- methods of solvent purification. aqueous Media, Allyn & Bacon, Needham 21 Safarik, L., Stransky, Z. Titrimetric Heights, MA, 1973. Analysis in Organic Solvents, Comprehen- 9 Trémillon, B. Chemistry in Nonaqueous sive Analytical Chemistry, Vol. 22, Else- Solvents, D. Reidel, Dordrecht, the vier, Amsterdam, 1986.