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The self-consistent spectrophotometric acidity scale of neutral Bronsted acids in acetonitrile (AN) spanning 24 orders of magnitude of acidities is reported. The scale includes 93 acids that are interconnected by 203 relative acidity measurements and contains compounds with gradually changing acidities, including representatives from all of the conventional families of OH, NH and CH acids.

Several nonionic superbasic phosphazene bases, tetramethylguanidino-substituted at the P atom, are synthesized and the base strength of these compounds is established in tetrahydrofuran (THF) solution by means of spectrophotometric titration. The gas phase basicities of numerous guanidino- and N',N',N',N'-tetramethylguanidino-substitited phosphazenes and their cyclic analogues are also calculated.

Results discuss the relative ion-pair basicities of 25 substituted aryl and alkyl iminophosphoranes and 20 N-bases in THF medium. Data indicate that the basicity for 2-methoxypyridine to EtP(sub)1(pyrr) spans over 18 pK units.

Research demonstrates determination of basicity by analyzing 29 different bases in acetonitrile on a scale of pK(sub)a value of 12.33 of pyridine. Data on a total of 53 equilibrium constants each describing the basicity of two bases are presented.

A unified self-consistent scale of acidity in acetonitrile in the range of 4-16 pKa units has been developed. It comprises 74 independent equilibrium constant measurements, each providing a detailed account of the relative acidity of two acids. The quantitative ultraviolet-vis spectrophotometric scale helps set a solid foundation for the reliable pKa determinations of strong acids in acetonitrile. This demonstrates that the acidities of strong acids can be readily measured, with acetonitrile an appropriate medium for the undertaking.

The bis-guanidino compound [H.sub.2]C[{hpp}.sub.2] (hppH = 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) is converted to the monocation and isolated as the chloride and tetraphenylborate salts. Triadic analysis has shown that the dominant term causing the high basicity is the relaxation energy.

A general route is described for functionalized pentakis(trifluoromethyl)phenyl ([C.sub.6][(C[F.sub.3]).sub.5]) derivatives. The origin of the acidifying effect of the [C.sub.6][(C[F.sub.3]).sub.5] group is explored by using the isodesmic reactions approach.

The goal of the study is to expand significantly the existing self-consistent scale toward superbasic direction and also toward weaker neutral organic bases for several pKa units. The revised basicity scale was interconnected with the self-consistent acidity scale by delta(pKa) measurements between acids and bases.

The Staudinger or the Kirsanov reactions have synthesized eleven new phenyl-substituted phosphazenes (P1-, P3-, and P4- bases). The objective is to extend the basicity scale into the region of stronger bases.

Research has been conducted on heptane. The authors report that the UV-vis spectrophotometric ion-pair acidity scale in heptane has been expanded.

A method for creating self-consistent acidity and basicity scales in nonaqueous solvents is presented and the current progress in applying such scales to different solvents is reviewed. The method is based on UV-Vis spectrophotometric titration of a mixture of two acids (or two bases) with a non-absorbing base (acid). From the titration data the relative acidity (relative basicity) of the two compounds — the difference of their pKa values (ΔpKa) — is obtained. When a large set of compounds that have different acid (base) strengths is available and ΔpKa measurements are carried out in such a way that each compound is measured against several other compounds, a self-consistent acidity (basicity) scale can be built. The relative acidities (basicities) of the compounds included in the scale can be determined at very high accuracy: many of the error sources, most importantly moisture and impurities in the solvent and in the compounds, influence both compounds in a similar way and at least partially cancel out. Using this method, self-consistent acidity scales have been created in heptane and acetonitrile and self-consistent basicity scales have been developed in acetonitrile and THF. These scales are discussed and future plans are outlined. [ABSTRACT FROM AUTHOR]