Standard enthalpy of formation of La2CoO4(cr)

The enthalpies of reactions of La₂CoO₄(cr) and CoCl₂(cr) with hydrochloric acid were measured with an isothermal-jacket calorimeter. The results obtained and the available literature data were used to calculate the standard enthalpy of formation of La₂CoO₄(cr) at 298.15 K, Δ_f H ^o = ?2179 ± 7 kJ/mol.     

Synthesis and conversions of polyhedral compounds 17. Conversion of 1,3-diaza- and 1,3,5-triazaadamantanes to nitrogen-containing pentacyclic compounds

It has been shown that derivatives of 1,3-diaza- and 1,3,5-triazzaadaniantanes, and also derivatives of 3,7-diazabicyclo[3.3.1]nonane, interact with 3,7-bis(bromoacetyl)-3,7-diaza- and 3,7-bis(bronwacetyl)-1,3,7-triazabicyclo[3. 3. 1]nonanes in the presence of bases to form previously unknown types of heteropolyhedral structures — nitrogen-containing pentacyclic compounds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 106–110, January, 1994. Original article submitted October 20, 1993.     

Anti-oxidant and pro-oxidant reactivities of copper(II), manganese(II) and iron(III) 3,5-di-<Emphasis Type="Italic">i</Emphasis>-propylsalicylate chelates during peroxidation of alkylbenzenes

Bioactive copper(II), iron(III), and manganese(II) 3,5-di-i-propylsalicylate (3,5-DIPS) chelates were investigated in order to determine their ability to inhibit the free radical initiated chain reactions leading to the peroxidation of isopropylbenzene (i-PrPh) and ethylbenzene (EtPh). Quantitative kinetic studies of these chelates established the following order of anti-oxidant reactivities: manganese(II)-(3,5-DIPS)₂>iron(III)(3,5-DIPS)₃>copper(II)₂(3,5-DIPS)₄> > 3,5-DIPS acid. The mechanism of anti-oxidant reactivity of these three chelates is established as being due, in part, to their chain-breaking capacity resulting from the chemical reduction of the generated peroxyl radical to yield alkybenzenelhydroperoxides via reaction of the 3,5-DIPS ligand with the peroxyl radical. In the case of manganese(II)3,5-di-i-propylsalicylate, the central metalloelement also interacts with the peroxyl radical. The manganese(II)-(3,5-DIPS)₂ and copper(II)₂(3,5-DIPS)₄ chelates were also found to exhibit alkylhydroperoxide pro-oxidative reactivity leading to the formation of the alkylbenzeneperoxyl radical. In addition, the manganese(II) atom underwent oxidation to manganese(III) with the formation of the alkylbenzenehydroperoxide or superoxide with air oxygen oxidation. Amyl acetate and dipropylamine (n-Pr₂NH) were added to the reaction mixture to model the biochemical presence of ester or amine cellular components. Addition of amyl acetate to the reaction mixture increased the anti-oxidant reactivity of manganese(II)-(3,5-DIPS)₂ while decreasing its pro-oxidant reactivity. The weaker anti-oxidant reactivites of iron(III)(3,5-DIPS)₃ and copper(II)₂(3,5-DIPS)₄ were less affected by the addition of amyl acetate and the pro-oxidant reactivity of copper(II)₂(3,5-DIPS)₄ was not changed by the addition of amyl acetate, while the pro-oxidant property of iron(III)(3,5-DIPS)₃ was eliminated. In contrast to 2,6-di-t-butyl-4-methylphenol, butylated hydroxy toluene (BHT), anti-oxidant reactivities of copper(II), iron(III), and manganese(II) 3,5-DIPS chelates were dramatically enhanced by the addition of n-Pr₂NH to the reaction mixture. It is concluded that all three metalloelement chelates react with and remove alkylbenzeneperoxyl radicals and the hydroperoxyl radical. The manganese(II)-(3,5-DIPS)₂ and copper(II)₂(3,5-DIPS)₄ chelates may also be useful in removing hydroperoxides in vivo. These reactivities, in addition to their established superoxide dismutase (SOD)-mimetic and catalase-mimetic reactivities, are suggested to possibly permit anti-oxidant and pro-oxidant reactivities in aqueous and organic cellular compartments.     

Determination of the Kinetic Significance of Elementary Steps in the Reaction of Ethylbenzene Oxidation Inhibited by para-Substituted Phenols: Choice of an Effective Antioxidant

A conceivable method (value method) for analyzing the reaction kinetics models of inhibited liquid-phase oxidation of organic compounds was considered. A procedure for the numerical calculations of the molecular structure parameters of an inhibitor and an inhibitor concentration that results in a maximum inhibition of the reaction was presented. In the kinetic model of a chain reaction of liquid-phase ethylbenzene oxidation in the presence of a para-methylphenol inhibitor, the dynamics of contributions from individual steps was calculated. This allowed us to simplify the reaction mechanism. The inhibition of the oxidation reaction due to reactions with the participation of a phenoxyl radical was found to occur under conditions of the quasi-equilibriumRO ₂ ^· +HO'RRO₂H +OC₆H₄'RThe molecular structures and initial concentrations of para-substituted phenols, which are most effective for the given reaction conditions, were determined.     

1,2,4-Triazole-Based Hybrid Heterocyclic Carbaldehyde Hydrazones and Their Effect on DNA Methylation Level

Russian Journal of Organic Chemistry - While developing new approaches to the design of biologically active compounds based on 1,2,4-triazole, a number of new hydrazones containing...     

Study of the heat-strength of PENTELAST one-component silicon adhesive-sealants

This work presents the results of testing the changes in the physical and mechanical parameters of PENTELAST adhesive-sealants due to isothermal aging at 200, 250, and 300°C within a period of 10 days. The operating temperature ranges are determined in which the PENTELAST adhesive-sealants may be used without impairing the strength and elastic properties. It is clearly shown that PENTELAST-1159 and PENTELAST-1161 materials have the maximal heat strength.     

Differential pulse voltammetric studies of ethidium bromide binding to DNA

The interaction of ethidium bromide (EtBr) with calf thymus DNA is investigated electrochemically with the use of differential pulse voltammetry (DPV) at two different ionic strengths of a solution (0.154 M and 0.02 M [Na+], pH 7.0). It is revealed that EtBr binds with DNA in more than one way. The appropriate values of constants (K) and number site sizes (n) of EtBr binding to DNA are determined. The values of binding constants are equal to 1.9 x 10(6) and 5.6 x 10(5) M(-1), and number site sizes to 9 and 3.6 for strong interactions at ionic strengths of solutions 0.02 and 0.154 M Na+ at 28 degrees C, respectively. For a weaker interaction, these parameters are equal to 7 x 10(4) and 8 x 10(4) M(-1) and 1.5 and 1 at the mentioned ionic strengths of solutions, respectively. Thus, EtBr interacts with DNA in more than one way--intercalative and electrostatic at low ionic strength, and semi-intercalative and electrostatic at a higher strength of the solution. These results are in good accordance with the ones obtained by spectroscopic (absorption and fluorimetric) methods.     

New DNA Methylation Inhibitors Based on 1,2,4-Triazole Thioether Derivatives

New 4-substituted 4H-1,2,4-triazole-3-thiol derivatives were synthesized by introducing benzylsulfanylethyl groups in the 5-position of the heterocycle. Alkylation of the thiol group provides additional pharmacophore thioether, carboxamide, carboxyl, and hydroxyethyl fragments. Regardless of the nature of the substituents in the position 5 aminomethylation and cyanoethylation proceed at the N₂ atom. The synthesized compounds were studied for anti-tumor activity and the effect on the methylation level of tumor DNA.     

Synthesis and conversions of polyhedral compounds 20. Synthesis of certain derivatives of 3,7-diazabycyclo[3.3.1]nonane

1,3-Diazaadamantanes containing hydrogen atoms or a hydroxyl or oxime group at C₍₆₎, under the action of 2 moles of aralkyl halides, are converted in alkaline aqueous media to 3,7-diaralkyl-3, 7-diazabi cyclo(3.3.1]nonanes containing the indicated groups at C₍₉₎. Analogously, quaternary salts of 1,3-diaza-adamantanes containing hydrogen atoms or a hydroxyl group at C₍₆₎ are converted in an alkaline aqueous medium to the corresponding 3-alkyl-3,7-diazabicyclo[3.3.1]nonanes containing the indicated groups at C₍₉₎.For Communication 19, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 401–406, March, 1994.