Acid-base chemistry nonaqueous systems

Almost all of the reactions that the practicing inotganic chemist observes in the laboratory take place in solution. Although water is the best-known solvent, it is not the only one of importance to the chemist. The organic chemist often uses nonpolar solvents sud) as carbon tetrachloride and benzene to dissolve nonpolar compounds. These are also of interest to Ihe inoiganic chemist and, in addition, polar solvents such as liquid ammonia, sulfuric acid, glacial acetic acid, sulfur dioxide, and various nonmctal halides have been studied extensively. The study of solution chemistry is intimately connected with acid-base theory, and the separation of this material into a separate chapter is merely a matter of convenience. For example, nonaqueous solvents are often interpreted in terms of the solvent system concept, the formation of solvates involve acid-base interactions, and even redox reactions may be included within the (Jsanovich definition of acid-base reactions. 

When one considers the incredible number of chemical reactions that are possible, it becomes apparent why a scheme that systemizes a large number of reactions is so important and useful. Indeed, classification of reaction types is important in all areas of chemistry, and a great deal of inorganic chemistry can be systematized or classified by the broad types of compounds known as acids and bases. Many properties and reactions of substances are understandable, and predictions can often be made about their reactions in terms of acid-base theories. In this chapter, we will describe the most useful acid-base theories and show their applications to inorganic chemistry. However, water is not the only solvent that is important in inorganic chemistry, and a great deal of chemistry has been carried out in other solvents. In fact, the chemistry of nonaqueous solvents is currently a field of a substantial amount of research in inorganic chemistry, so some of the fundamental nonaqueous solvent chemistry will be described in this chapter. 

Their unique relation to water systems favors the inclusion of acid-base reactions in deuterium oxide with aqueous acid-base equilibria, even though some aspects of the chemistry suggest inclusion with nonaqueous solvents. In studies such as those of deuterium isotope effects, it is desirable to be able to measure pD as an index of acidity in heavy water. Glass electrodes respond in a nemstian way to changes in deuterium ion concentration, and therefore the usual combination of glass and calomel electrodes can form the basis of an operational definition of pD ... 

It is practical to divide solvents into two groups, protic and aprotic solvents. Protic solvents are those that have protons bonded to heteroatoms and include acids, neutral solvents, and some bases. A review of solvents useful for electrochemistry has appeared [289]. Electrochemical reactions in nonaqueous systems [290] and the chemistry of non-aqueous solvents [291] have been treated in monographs. 

In the 1960s, remarkable new chemistry emerging mainly from Olah s studies drew attention to highly acidic nonaqueous systems. New information including the preparation of stable solutions of carbocations, the formation of new inorganic cations, and the successful protonation of vmusually weak bases, such as alkanes, required fundamental studies. One of the most basic properties of these systems is their unusually high acidity. 

King, E. J., Acid-base behaviour, in Physical Chemistry of Organic Solvent Systems (A. K. Covington and T. Dickinson, eds.). Plenum Press, London, 1973, pp. 331-403. Kolthoff, I. M. and M. K. Chantooni, General introduction to acid-base equilibria in nonaqueous organic solvents, in Treatise on Analytical Chemistry, Parti, Theory and Practice (I. M. Kolthoff and P. J. Elving, eds.), John Wiley Sons, New York, 1979, pp. 239-301. 

---