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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.

The pK(sub a) values in DMSO for 22 di- and triprotected hydrazine NH acids and two monosubstituted hydrazines is determined using potentiometric titration. The results stated that for the protected hydrazine compounds under study, the pK(sub a) values distinctly reflect structural features and exhibit a total span of about 21 units.

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.

The acidities of CH3-nFnOH and CH3-nFnSH (n = 0-3) have been calculated at the G2 level of theory. Attention is given to the factors driving the behaviour of the geometries and energetics of these species and their heterolytic and homolytic dissociation products.

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.

Measurements of relative acidities in heptane can be obtained through an ultraviolet-vis spectrophotometry. The phosphazene base t-BuP4 can be employed as the deprotonating agent. Its protonated form is a good counterion for the anions of the acids due to its bulkiness and its delocalized charge. Hence, it does not have specific interactions with the anions. A self-consistent scale of relative acidities in heptane spanning for 3 pKa units has been developed.

FT-ICR mass spectrometric technique helps determine the gas-phase acidity of 1H-undecafluorobicyclo(2.2.1)heptane, 1H, 4H-decafluorobicyclo(2.2. 1)-heptane and (CF3)3CH. Open chain (CF3)3CH exhibits higher acidity than the other two. Bridge-head counterparts result from the failure of these acids to form planar anionic structures, which are necessary for maximum hyperconjugation. Experimental results support the role of anionic hyperconjugation on the stability of aliphatic fluorosubstituted carbanions.

The pulsed FT ion cyclotron resonance equilibrium constant method was used to obtain gas-phase acidities of very strong, neutral Bronsted acids. The strongest gas-phase superacid to be measured was (C4F9SO2)2NH. Information regarding strong gas-phase superacids may be applied to condensed-phase chemistry.

The polyfluorination and polytrifluoromethylation effects on electronic structure and intrinsic acidities are studied by using DFT B3LYP and NBO calculations for the valence isomers of benzene and phenol, that is, the structures of prismane, benzvalene, Kekule and Dewar systems. The isomerization of the benzene derivatives has resulted in cases where the acidities increased when compared to the respective phenol derivatives.

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.

Several experiments are conducted to supplement and extend the experimental gas-phase basicity (GB) scale in the superbasic region by employing almost seventeen superbasic phosphazenes and two Verkade's bases in the study. The analysis provides the values of GB for all the metal-oxide, as well as organic bases, hence laying the pathway for further basicity investigations in this region.

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.

The carbonyl infrared stretching frequencies for 57 meta-, para- and ortho-substituted phenyl benzoates, C6H5CO2C6H4-X and alkylbenzoates, C6H5CO2R, containing besides neutral substituents the charged substituents in phenoxy and alkoxy part in dimethyl sulfoxide (DMSO) have been recorded. The carbonyl stretching frequencies, νCO, for meta- and para-substituted phenyl esters of benzoic acids in the case of neutral substituents were found to correlate well with the substituent constants, σ°. The νCO values for ortho derivatives correlated with the inductive substituent constants, σI, only. The values of constants for charged substituents, σ°±, calculated on the basis of the νCO and the 13C NMR chemical shifts, δCO, in DMSO agree well with the σ°± values for the corresponding ion pairs reported by Hoefnagel and Wepster and those determined from the log k values of the alkaline in 4.4 M NaCl solution at 50 °C. Thus, the values of substituent constants for ion pairs of charged substituents estimated on the basis of aqueous data could be successfully used in non-aqueous solution (DMSO) simultaneously with neutral substituents in case the charged substituents were not completely ionized and are in ion pair form. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]