Experimental Modeling of Formation of the Basic Mineral Phases of Calcifications

Calcium phosphate phase formation was studied under process conditions involving human blood plasma. Calcium phosphate was synthesized with variable supersaturation (S) and experimental time. It was found that a non-stoichiometric hydrated carbonated hydroxyapatite, identical in the composition to calcifications in humans, is formed under the experimental conditions. The highest amount of carbonate ions (5.54 wt %) in the solid phase corresponds to the apatite synthesized at S = 50 for 10 weeks. The dissolution rate of solid phases was determined by mathematical processing of the obtained kinetic curves; this can be used to find compounds able to stop the development of vascular calcinosis.     

Main regularities of crystallization of calcium oxalate in the presence of amino acids

Processes of crystallization of calcium oxalate from aqueous solutions are investigated. Main regularities of the nucleation and crystal growth of calcium oxalate during mass crystallization without admixtures and in the presence of amino acids are established. The inhibiting action of the aspartic and glutamic amino acids on the growth of calcium oxalate crystals is demonstrated. Addition of amino acids does not affect the nucleation kinetics.     

IR spectra of substituted pyrroles

The IR spectra of 52 substituted pyrroles, including 24 1-vinylpyrroles, were thoroughly analyzed. The principal analytical bands of the pyrrole ring and the vinyl group were isolated. Doublet character of the bands of the stretching vibrations of the double bond ( ^v C=C) and the C-H (CH₂=) out-of-plane deformation vibrations, which indicates the presence of rotational isomerism relative to the N-vinyl bond, was detected. The integral intensify of the principal component of the ^v C=C doublet was measured for 12 of the 1-vinylpyrroles, and it is shown that it is practically independent of the structure of the alkyl substituents in the ring. Proof for the existence of a nonplanar gauche conformation for the 1-vinylpyrroles was obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 910–914, July, 1977.     

Solid-Phase Solvate-Free Formation of Magnesium Hydroaluminates Mg(AlH4)2and MgAlH5upon Mechanochemical Activation or Heating of Magnesium Hydride and Aluminum Chloride Mixtures

It is shown that vibromechanically activated or heated magnesium hydride is capable of solid-phase interacting with aluminum chloride to form magnesium tetra- and pentahydroaluminates (Mg(AlH₄)₂and MgAlH₅). When heated above 100°C, Mg(AlH₄)₂undergoes thermolysis (or mechanolysis upon mechanical activation) to form MgAlH₅and AlH₃. The latter liberates aluminum and hydrogen in the moment of isolation. In the 230 to 280°C interval, MgAlH₅also loses reactive AlH₃ . On further heating, the obtained active aluminum and MgH₂give intermetallide Al₂Mg. The ability of Mg(AlH₄)₂to transform into MgAlH₅by the addition of excessive activated MgH₂, as in the case of Sr(AlH₄)₂, is revealed.     

Pyrroles from ketoximes and acetylene. 14. Quantitative estimate of the effect of substituents on the NH acidities of pyrroles

The pK values of a series of substituted pyrroles and the vNH values (in dimethylformamide), which characterize their relative acidities were measured by the transmetallation method. It was established that the acidities of pyrroles are determined primarily by the inductive effect of the substituents and are virtually independent of the ability of the latter to enter into conjugation with the ring. This means that the electron pair of the anion that is set free in the ionization of pyrrole retains character. The linear dependences of the pK and NH values on the inductive constants (I) of the substituents can be used to estimate the pK values of various compounds that contain a pyrrole ring starting from the NH and I values.See [1] for communication 13.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 632–638, May, 1980.