A Study of Viscosity in the Extraction System Constituted by Tributyl Phosphate and Phosphoric Acid

Data on the kinematic viscosity of phosphoric acid solutions in technical-grade tributyl phosphate and in an industrial extract from a technological purification system based on tributyl phosphate, which contain 0–18% phosphoric acid in terms of P₂O₅, at 10–70°C are presented.     

TDDFT-modeling of theoretical UV spectra of binuclear sulfur-containing iron nitrosyl clusters and products of their decomposition

Russian Chemical Bulletin - The UV spectra of four binuclear sulfur-containing iron nitrosyl clusters, namely, cationic Fe2{[S(CH2)2NH3]2(NO)4}SO4·2.5H20 and...     

Molecular decomposition of polyolefins: Kinetic parameters and geometry of the transition state

The experimental data on the molecular decomposition of olefins ( 1 -pentens) of various structures to two olefins in a gas phase were analyzed by means of the parabola intersection method. The enthalpies and kinetic parameters characterizing such decomposition were calculated for eighteen reactions. Decomposition of olefins representing two-centered concerted re action was found to be characterized by a very high classic potential barrier of thermoneutral reaction (197.4 kJ/mol). The kinetic parameters (activation energy and velocity constant) of fifteen reverse reactions of formation of olefins from two alkenes were calculated using the parabola-intersection method. The factors affect ing the activation energy of the reactions of olefin decomposition and formation are discussed. Quantum chemical calculations of the transition state energy and geometry for six reactions of olefin decomposition were performed.     

Semiempirical Analysis of the Homolytic Decomposition of Peresters with the Concerted Cleavage of Two Bonds

The parabolic model of a bimolecular reaction is modified to study the monomolecular decomposition of molecules into radicals by the cleavage of several bonds. Together with the oscillation model of molecule decomposition with the concerted cleavage of several bonds, this model is used to analyze the kinetic data on the decomposition of 16 peresters with the simultaneous cleavage of C–C and O–O bonds. Parameters characterizing this decomposition are obtained and multiple variants in representing such decomposition in terms of the parabolic model are discussed.     

Features of the decomposition of the neutral nitrosyl iron complexes with aryl-containing thiolate ligands in various solvents. Reaction with glutathione

The decomposition of two neutral binuclear nitrosyl iron complexes (NICs) of the µ-S structural type and general composition [Fe₂(SR)₂(NO)₄]⁰ was studied in comparison. The exchange reaction of the thiophenol or 2-aminothiophenol thiolate ligand by glutathione (GSH) in neutral NICs was studied. The reaction system was analyzed by spectrophotometry to prove the presence of a new NICs with the GS^– ligand in it. It was found that, unlike the earlier studied binuclear cationic NICs of the µ-S type and general composition [Fe₂(µ-SR)₂(NO)₄]²⁺SO₄?nH₂O with cysteamine and penicillamine ligands in which both thiolate ligands exchange by GS^–, in these neutral complexes both thiolate ligands are de-tached by only one GSH ligand is attached. A water molecule is inserted into the second free site. It is assumed that the antitumor activity of the neutral NICs can be determined not only by their NO-donor activity but also by their ability to exchange the thiolate ligand by GS^–, i.e., "to remove" GSH from the medium as in the case of cationic NICs. The discovered reaction can prevent, most likely, the S-glutathionylation of important metabolites in the presence of GSH and is very significant for metabolism of NICs.     

Reactivity of alkyl iodides in molecular decomposition reactions

The experimental results for the concerted molecular decomposition of alkyl iodides RI to olefin and HI were analyzed in terms of the intersecting parabolas model (IPM). The activation energies (E) and rate constants (k) of the earlier unstudied reactions of the concerted molecular decomposition of RI were calculated on the basis of the enthalpy of the reaction and IPM algorithms. The factors that influence on E of RI decay were established: the enthalpy of the reaction, the energy of stabilization of radical R*, the length and force constant of the C—I bond, and the size of the halogen atom. The values of E and k for the backward reactions of HI addition to olefins were estimated.     

Diazo carbonyl derivatives of heterocycles. 5. Intramolecular cyclization of 2-hetarylmercaptoalkyl-diazo ketones. Synthesis of condensed 1,3-thiazin-5-ones

The intramolecular heterocyclization of 2-benzazolylmercaptoalkyl diazomethyl ketones under the influence of acidic agents leads to 1,3-thiazino[2,3-b]benzim-idazole, 1,3-thiazino[2,3-b]benzothiazolium, and 1,3-thiazino[2,3-b]benzoxazolium systems. Under similar conditions 2-quinolylmercaptoalkyl diazomethyl ketones form 1,3-thiazino[2,3-a]quinolinium systems.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 635–639, May, 1984.     

Reactivity of bromoalkanes in reactions of coordinated molecular decay

The results from experiments on reactions of the coordinated molecular decay of RBr bromoalkanes on olefin and HBr are analyzed using the model of intersecting parabolas (MIP). Kinetic parameters within the MIP are calculated from the experimental data, enabling calculation of the activation energies (E) and rate constants (k) of such reactions, based on the enthalphy of the reaction and the MIP algorithms. The factors affecting the E of the RBr decay reaction are established: the enthalphy of the reaction, triplet repulsion, the energy of radical R? stabilization, the presence of a π bond adjacent to the reaction center, and the dipole–dipole interaction of polar groups. The energy spectrum of the partial energies of activation is constructed for the reaction of coordinated molecular decay of RBr, and the E and k of inverse addition reactions are evaluated.     

Diazo carbonyl derivatives of heterocycles. 3. Alternative 1,3-dipolar addition to azidoalkyl α-diazo ketones and synthesis of five-membered heterocycles based on them

It is shown that the cycloaddition of dimethylacetylenedicarboxylate and N-phenylmaleinimide to azidoalkyl diazomethyl ketones leads to the corresponding 1,2,3-triazole and 2-pyrazoline derivatives. The electronic structure of one of the bisdipoles was determined.See [1] for communication 2.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 514–519, April, 1984.     

A study of post-radiation polymerization of 2-hydroxyethyl methacrylate γ-irradiated in crystalline and vitreous states

Dependent on the mode of preparation, 2-hydroxyethyl methacrylate (HEMA) can at low temperatures acquire either vitreous or crystalline states. On heating γ-irradiated vitreous HEMA, polymerization starts immediately after transition of the system from the vitreous state to that of a supercooled liquid (T_g = 177 K). This provides conditions for growth of polymer chains and suppression of bimolecular termination of active growing centres. Polymerization of radiated crystalline HEMA occurs at higher temperatures in the monomer melting region. At equal dosages of preliminary radiation, the transformation depth for the crystalline sample is considerably lower than that for the vitreous sample; this effect is due to different molecular mobilities in heated crystalline and vitreous samples. In HEMA post-polymerization, the very early transformation stages yielded an insoluble cross-linked polymer. This paper discusses the possible mechanism of cross-linking during polymerization of monomers of the HEMA type as a result of detachment of hydrogen from the carbon atom in the glycol group.