Homo-Diels-Alder reaction of a very inactive diene, bicyclo[2,2,1]hepta-2, 5-diene, with the most active dienophile, 4-phenyl-1,2,4-triazolin-3,5-dione. Solvent, temperature, and high pressure influence on the reaction rate

Solvent, temperature, and high pressure influence on the rate constant of homo-Diels-Alder cycloaddition reactions of the very active hetero-dienophile, 4-phenyl-1,2,4-triazolin-3,5-dione (1), with the very inactive unconjugated diene, bicyclo[2,2,1]hepta-2,5-diene (2), and of 1 with some substituted anthracenes have been studied. The rate constants change amounts to about seven orders of magnitude: from 3.95.10-3 for reaction (1+2) to 12200 L mol-1 s-1 for reaction of 1 with 9,10-dimethylanthracene (4e) in toluene solution at 298 K. A comparison of the reactivity (ln k2) and the heat of reactions (r-nH) of maleic anhydride, tetracyanoethylene and of 1 with several dienes has been performed. The heat of reaction (1+2) is -218 ± 2 kJ mol-1, of 1 with 9,10-dimethylanthracene -117.8 ± 0.7 kJ mol-1, and of 1 with 9,10-dimethoxyanthracene -91.6 ±0.2 kJ mol-1. From these data, it follows that the exothermicity of reaction (1+2) is higher than that with 1,3-butadiene. However, the heat of reaction of 9,10- dimethylanthracene with 1 (-117.8 kJ mol-1) is nearly the same as that found for the reaction with the structural C=C counterpart, N-phenylmaleimide (-117.0 kJ mol-1). Since the energy of the N=N bond is considerably lower (418 kJ/bond) than that of the C=C bond (611 kJ/bond), it was proposed that this difference in the bond energy can generate a lower barrier of activation in the Diels-Alder cycloaddition reaction with 1. Linear correlation (R = 0.94) of the solvent effect on the rate constants of reaction (1+2) and on the heat of solution of 1 has been observed. The ratio of the volume of activation (V≠) and the volume of reaction (V r-n) of the homo-Diels-Alder reaction (1+2) is considered as "normal": V≠/Vr-n = -25.1/-30.95 = 0.81. Copyright © 2012 John Wiley & Sons, Ltd

Dinuclear complexes of copper(I) with crown ether-containing N-thiophosphorylated bis-thioureas and 2,2'-bipyridine or 1,10-phenanthroline: Synthesis, characterization, and picrate extraction properties

Reaction of O,O'-diisopropylthiophosphoric acid isothiocyanate (iPrO) 2P(S)NCS with 1,10-diaza-18-crown-6, 1,7-diaza-18-crown-6, or 1,7-diaza-15-crown-5 leads to the N-thiophosphorylated bis-thioureas N,N'-bis[C(S)NHP(S)(OiPr)2]-1,10-diaza-18-crown-6 (H 2LI), N,N'-bis[C(S)NHP(S)(OiPr)2]-1,7-diaza-18- crown-6 (H2LII) and N,N'-bis[C(S)NHP(S)(OiPr) 2]-1,7-diaza-15-crown-5 (H2LIII). Reaction of the potassium salts of H2LI-III with a mixture of CuI and 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen) in aqueous EtOH/CH 2Cl2 leads to the dinuclear complexes [Cu 2(bpy)2LI-III] and [Cu2(phen) 2LI-III]. The structures of these compounds were investigated by 1H, 31P{1H} NMR spectroscopy, and elemental analysis. The crystal structures of H2LI and [Cu2(phen)2LI] were determined by single-crystal X-ray diffraction. Extraction capacities of the obtained compounds in comparison to the related compounds 1,10-diaza-18-crown-6, N,N'-bis[C(=CMe2)CH2P(O)(OiPr)2]-1,10-diaza-18- crown-6, N,N'-bis[C(S)NHP(O)(OiPr)2]-1,10-diaza-18-crown-6 towards the picrate salts LiPic, NaPic, KPic. and NH4Pic were also studied. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Coordination mode of the nickel(II) cation with N-diisopropoxyphosphinyl-p- bromothiobenzamide

Reaction of the potassium salt of N-diisopropoxyphosphinyl-p- bromothiobenzamide p-BrC6H4C(S)NHP(O)(OiPr)2 (HL) with Ni(NO3)2 in aqueous EtOH leads to complex of formula [Ni(HL-O)2(L-O,S)2] (1). The structure of 1 was investigated by single crystal X-ray diffraction analysis, IR, 1H and 31P{1H} NMR spectroscopy, MALDI and microanalysis. The nickel(II) ion in 1 has a tetragonal-bipyramidal environment, (O ax)2(Oeq)2(Seq) 2, with two neutral ligand molecules coordinated in axial positions through the oxygen atoms of the P=O groups. The equatorial plane of bipyramide is formed by two anionic ligands involving 1,5-O,S-coordination mode. The chelating ligands are bound in trans configuration. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA

Role of salicylic acid in acclimation to low temperature

Low temperature is one of the most important limiting factors for plant growth throughout the world. Exposure to low temperature may cause various phenotypic and physiological symptoms, and may result in oxidative stress, leading to loss of membrane integrity and to the impairment of photosynthesis and general metabolic processes. Salicylic acid (SA),phenolic compound produced by a wide range of plant species, a may participate in many physiological and metabolic reactions in plants. It has been shown that exogenous SA may provide protection against low temperature injury in various plant species, while various stress factors may also modify the synthesis and metabolism of SA. In the present review, recent results on the effects of SA and related compounds in processes leading to acclimation to low temperatures will be discussed

Homo-Diels-Alder reaction of a very inactive diene, bicyclo[2,2,1]hepta-2, 5-diene, with the most active dienophile, 4-phenyl-1,2,4-triazolin-3,5-dione. Solvent, temperature, and high pressure influence on the reaction rate

Solvent, temperature, and high pressure influence on the rate constant of homo-Diels-Alder cycloaddition reactions of the very active hetero-dienophile, 4-phenyl-1,2,4-triazolin-3,5-dione (1), with the very inactive unconjugated diene, bicyclo[2,2,1]hepta-2,5-diene (2), and of 1 with some substituted anthracenes have been studied. The rate constants change amounts to about seven orders of magnitude: from 3.95.10-3 for reaction (1+2) to 12200 L mol-1 s-1 for reaction of 1 with 9,10-dimethylanthracene (4e) in toluene solution at 298 K. A comparison of the reactivity (ln k2) and the heat of reactions (r-nH) of maleic anhydride, tetracyanoethylene and of 1 with several dienes has been performed. The heat of reaction (1+2) is -218 ± 2 kJ mol-1, of 1 with 9,10-dimethylanthracene -117.8 ± 0.7 kJ mol-1, and of 1 with 9,10-dimethoxyanthracene -91.6 ±0.2 kJ mol-1. From these data, it follows that the exothermicity of reaction (1+2) is higher than that with 1,3-butadiene. However, the heat of reaction of 9,10- dimethylanthracene with 1 (-117.8 kJ mol-1) is nearly the same as that found for the reaction with the structural C=C counterpart, N-phenylmaleimide (-117.0 kJ mol-1). Since the energy of the N=N bond is considerably lower (418 kJ/bond) than that of the C=C bond (611 kJ/bond), it was proposed that this difference in the bond energy can generate a lower barrier of activation in the Diels-Alder cycloaddition reaction with 1. Linear correlation (R = 0.94) of the solvent effect on the rate constants of reaction (1+2) and on the heat of solution of 1 has been observed. The ratio of the volume of activation (V≠) and the volume of reaction (V r-n) of the homo-Diels-Alder reaction (1+2) is considered as "normal": V≠/Vr-n = -25.1/-30.95 = 0.81. Copyright © 2012 John Wiley & Sons, Ltd

Multifactorial mathematical modeling of demand for medications to treat bronchial asthma for the hospitals of the republic of Tatarstan

The correlation and regression analysis between the need for medications to treat bronchial asthma at the hospitals and epidemiological, demographic, medical, and social factors was carried out. The designed mathematical multifactorial models-based prognosis of demand for medications to treat bronchial asthma for hospitals of the Republic of Tatarstan was given

Homo-Diels-Alder reaction of a very inactive diene, bicyclo[2,2,1]hepta-2, 5-diene, with the most active dienophile, 4-phenyl-1,2,4-triazolin-3,5-dione. Solvent, temperature, and high pressure influence on the reaction rate

Solvent, temperature, and high pressure influence on the rate constant of homo-Diels-Alder cycloaddition reactions of the very active hetero-dienophile, 4-phenyl-1,2,4-triazolin-3,5-dione (1), with the very inactive unconjugated diene, bicyclo[2,2,1]hepta-2,5-diene (2), and of 1 with some substituted anthracenes have been studied. The rate constants change amounts to about seven orders of magnitude: from 3.95.10-3 for reaction (1+2) to 12200 L mol-1 s-1 for reaction of 1 with 9,10-dimethylanthracene (4e) in toluene solution at 298 K. A comparison of the reactivity (ln k2) and the heat of reactions (r-nH) of maleic anhydride, tetracyanoethylene and of 1 with several dienes has been performed. The heat of reaction (1+2) is -218 ± 2 kJ mol-1, of 1 with 9,10-dimethylanthracene -117.8 ± 0.7 kJ mol-1, and of 1 with 9,10-dimethoxyanthracene -91.6 ±0.2 kJ mol-1. From these data, it follows that the exothermicity of reaction (1+2) is higher than that with 1,3-butadiene. However, the heat of reaction of 9,10- dimethylanthracene with 1 (-117.8 kJ mol-1) is nearly the same as that found for the reaction with the structural C=C counterpart, N-phenylmaleimide (-117.0 kJ mol-1). Since the energy of the N=N bond is considerably lower (418 kJ/bond) than that of the C=C bond (611 kJ/bond), it was proposed that this difference in the bond energy can generate a lower barrier of activation in the Diels-Alder cycloaddition reaction with 1. Linear correlation (R = 0.94) of the solvent effect on the rate constants of reaction (1+2) and on the heat of solution of 1 has been observed. The ratio of the volume of activation (V≠) and the volume of reaction (V r-n) of the homo-Diels-Alder reaction (1+2) is considered as "normal": V≠/Vr-n = -25.1/-30.95 = 0.81. Copyright © 2012 John Wiley & Sons, Ltd

Dinuclear complexes of copper(I) with crown ether-containing N-thiophosphorylated bis-thioureas and 2,2'-bipyridine or 1,10-phenanthroline: Synthesis, characterization, and picrate extraction properties

Reaction of O,O'-diisopropylthiophosphoric acid isothiocyanate (iPrO) 2P(S)NCS with 1,10-diaza-18-crown-6, 1,7-diaza-18-crown-6, or 1,7-diaza-15-crown-5 leads to the N-thiophosphorylated bis-thioureas N,N'-bis[C(S)NHP(S)(OiPr)2]-1,10-diaza-18-crown-6 (H 2LI), N,N'-bis[C(S)NHP(S)(OiPr)2]-1,7-diaza-18- crown-6 (H2LII) and N,N'-bis[C(S)NHP(S)(OiPr) 2]-1,7-diaza-15-crown-5 (H2LIII). Reaction of the potassium salts of H2LI-III with a mixture of CuI and 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen) in aqueous EtOH/CH 2Cl2 leads to the dinuclear complexes [Cu 2(bpy)2LI-III] and [Cu2(phen) 2LI-III]. The structures of these compounds were investigated by 1H, 31P{1H} NMR spectroscopy, and elemental analysis. The crystal structures of H2LI and [Cu2(phen)2LI] were determined by single-crystal X-ray diffraction. Extraction capacities of the obtained compounds in comparison to the related compounds 1,10-diaza-18-crown-6, N,N'-bis[C(=CMe2)CH2P(O)(OiPr)2]-1,10-diaza-18- crown-6, N,N'-bis[C(S)NHP(O)(OiPr)2]-1,10-diaza-18-crown-6 towards the picrate salts LiPic, NaPic, KPic. and NH4Pic were also studied. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim