Progress in the Analysis of Inorganic and Organic Compounds in Non-Aqueous Solutions

Abstract

The unrelaxed excited states of atomic hydrogen centres in a mixed configuration in alkali halides, in which the hydrogen atom is tetrahedrally surrounded by three host anions and one heavier anion-HP(Br, I) centres-have been investigated for six configurations by means of magneto-optical and optical measurements. With a simple charge-transfer model for the optical transitions it is possible to explain quantitatively the oscillator strength, the change of the first moment of the magnetic circular dichroism and the energy splitting of the optical absorption bands. The unrelaxed excited state can be described as a charge-transfer state, in which two electrons reside at the interstitial H-ion, one in a 1s-type orbital and one in a 2s-type orbital, and one hole resides in an outer p orbital of the heavier anion, whereby the charge transfer is incomplete. The best agreement was obtained for a degree of transfer of H.

Exploring Reversible Quenching of Fluorescence from a Pyrazolo[3,4‐b]quinoline Derivative by Protonation

“…[44] However, in ethanolic solution, HCl is a medium-strength acid (much weaker than in water) with pK A % 1.98. [45] Therefore, HCl in ethanol may not dissociate completely into H + and Cl À , and the [H + ] concentration will be much lower than the prepared concentration of [HCl]. An equilibrium dissociation process of HCl must then be taken into account, and this can be expressed as Equation (8)…”

“…[HCl] 1/2 ). Taking pK A of HCl in ethanol to be 1.98, as reported in reference [45], we obtain the static quenching constant to be K S = 1.95 m À1 .…”

Organic Microchemistry

“…Kreshkov and co-workers in a series of papers (226,227,230, 232) presented a number of methods for the analysis of silicon-containing organic compounds. Fritz and Burdt (110) proposed reaction with bromine for SiH and SiCeHs groups.…”

Potentiometric Titrations

“…This method has been extended to the use of sulfuric acid in place of perchloric acid and benzene solvent (120). A procedure for differentiating titration of production mixtures of nitric acid and a-hydroxyisobutyrie acids in methyl ethyl ketone or acetone solvent and glass electrode indicator system has been described by Kreshkov et al (116). A potentiometric method has been developed by Kreshkov,Bykova,and Pevzner (115) for the analysis of aromatic diamine monomers of types employed to produce heterochain polyamides.…”