On acid-base properties

In many problems of peptide sequencing and peptide synthesis it is necessary to be able to separate mixtures of peptides and proteins. The principal methods used for this purpose depend on acid-base properties or on molecular sizes and shapes. 

Which analytic or preparative technique is based on acid-base properties of... 

Solvatochromism and specific features of interaction between nitropyrazoles and amphiprotic solvents have been studied in detail by Prof. Turchaninov s team [1119-1123, 1127]. The dependence on acid-base properties of solvents of the electron transition in 4-nitropyrazole connected with intramolecular charge transfer has been analyzed [1121], Amphiprotic solvents with a pronounced acidic function form with 4-nitropyrazole cyclic solvates. The results of ab initio calculations 6-31G show that a cyclic complex of both 4-nitropyrazole and 3-nitropyrazole with one water molecule is thermodynamically more stable than a linear complex of the same composition by 0.38 and 1.0 kcal/mol, accordingly [1120-1123] ... 

Effect of nonaqueous solvents on acid-base properties of NGu) (Acidic in dimethyl-formamide, pyridine and acet basic in HAc and formic acid) 26) E. Ripper, Explosivst 17 (7), 145-51 (1969) Bt CA 72, 48454(1970) (a-and /3-Nitroguanidine) (Reinvestigation of both forms by IR UV, Nuclear Magnetic Resonance (NMR), Differential Thermal Analysis (DTA),... 

This section will provide brief accounts of some representative synthetic procedures for preparation of solutes in superacidic media and of compounds which are derived from superacids and which owe their peculiar properties to their formation and stability under extremely weakly or strongly basic conditions. A large proportion of the examples will, of necessity, be drawn from studies using HF as solvent or reactant. This is because, in the case of HF, somewhat more inorganic chemistry has been published, to date, on acid-base properties of the solvent itself, on the nature of solutes, on unusual solutions produced in the solvent or on compounds derived from the solvent than is the case for HS03F, with even less available for CF3S03H. 

The influence of the mentioned parameters on acid-base properties can be considered on the basis of force characteristics of ions, which, unlike electronegativities, are more sensitive to the electron structure of elements [24], This is explained by the fact that the equation for the force characteristics Yi, determined as a ratio of n-ionization potential I to efficient radius fj,... 

The enthalpies of combustion, vapour pressures, enthalpies of sublimation, and enthalpies of formation (Af//° ,(g) = 42.9 and 55.9 kcal mol , respectively) of pyrazole and indazole have been measured <87MI 301-03). The effect of jV-methylation on acid-base properties of azoles, including the pyrazole/7V-methylpyrazole pair, has been studied by calorimetry in water and in DMSO (enthalpies of solution, enthalpies of vaporization or sublimation, and enthalpies of solvation) <89JP0646>. 

The effect of Y-AI2O3 modifying with silica on acid-base properties of the surface... 

Excitation of this type does not involve any appreciable charge separation, and the effect on acid-base properties is thus small. 

The Miscellaneous section (8.1.5) is divided in three parts subsection 8.1.5.1 on disproportionation-combination ratios is self-explanatory. Subsection 8.1.5.2 on isotope effects includes the results of experiments that yield only the isotope effect, as well as ratios derived from data in sections 8.1.3 and 8.1.4 however, special care has been taken to use only data that is fully compatible, avoiding ratios of individual rate constants that had been obtained under different conditions. Subsection 8.1.5.3 on acid-base properties lists only one entry and even this one is a tentative value. 

IBLG See questions from The Effect of Structure on Acid-Base Properties ... 

Figure 12. The effect of variations of substituents on the pjn idine ring of H 83/69 on acid-base properties (pX a) and their influence on the inhibitory acton on gastric acid secretion in the dog. Data represent an extract from the chemical synthesis program.

In order to prove/check the consistency of experimental data obtained in PT and CT, the principle of triads , raised first time elsewhere,will be presented in extended versions, with D and T as mixed-solvent systems, containing also some modifying agent Z, introdnced intentionally, in order to extend the pH-range covered by experimental points, obtained in PT and CT. These modifications were introduced to extend the possibilities offered by the new method of gaining a physicochemical knowledge on acid-base properties of some (mono- and polyprotic) acids in binary-solvent media. 

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