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The solid state reactions between TiO2 and Na2S2O8 or K2S2O8 have been investigated using TG, DTG, DTA, IR, and X-ray diffraction studies in the range of 20 to 1000°C.It has been shown that TiO2 reacts stoichiometrically (1 : 1) with Na2S2O8 in the range of 160 and 220°C forming the complex sodium monoperoxodisulfato—titanium(IV) as characterized by IR and X-ray analysis. The new complex then decomposes into the reactants above 190°C.An exothermic reaction has been observed between TiO2 and molten K2S2O7 at mole ratio 1:2 respectively and higher, in the range of 280 and 350°C. The IR and X-ray analyses have shown the formation of a complex namely, potassium tetrasulfato titanium(IV) for which the formula and structure have been proposed. This complex decomposes at higher temperatures into K2SO4 and a mixed sulfate of potassium and titanium. The mixed sulfate melts at 620°C and decomposes into K2SO4, TiO2, and the gaseous SO3.On the other hand, Na2S2O8 decomposes in a special mode producing a polymeric product of Na10S9O32. Decomposition of this species occurs after melting at 560°C into Na2SO4 and sulfur oxides. The decomposition reaction has been proved to be catalysed by TiO2 itself. 相似文献
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The biomimetic catalytic enantioselective addition of aldehydes to amines is reported. This was accomplished by combining biomimetic coupled catalytic aerobic oxidation of amines involving ruthenium-induced dehydrogenation and organocatalytic asymmetric Mannich reactions. The novel one-pot reactions furnished β-amino aldehyde and α-amino acid derivatives in high yields with excellent chemoselectivity and up to >99% ee. 相似文献
4.
The carbon-13 chemical shifts of seven N-(4-substituted phenyl) piperidine; the corresponding N-oxides, and their thermal rearrangement products were analyzed and assigned. The N-oxidation effect on the carbon-13 chemical shift is discussed, a correlation of N-oxidation effect with substituent constant (σp, σm, σI and σR) has been studied; dual substituent-parameter equation produce better correlation. 相似文献
5.
In the present paper, conformal spherical symmetric perfect fluid solutions to Einstein’s field equations are obtained by using the invariance of the equations under the Lie group of transformations. All the solutions thus obtained are analyzed physically. 相似文献
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Al-Ameen Bariz OmarAli Ahmed Jasim M. Al-Karawi Adil A. Awad Necmi Dege Sevgi Kansz Erbil Agar Zaman Ahmed Hussein Iman Rajab Mohammed 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(5):476-482
Reaction of N,N′‐(cyclohexane‐1,2‐diylidene)bis(4‐fluorobenzohydrazide), C20H18F2N4O2, ( LF ), with zinc chloride and mercury(II) chloride produced different types and shapes of neutral coordination complexes, namely, dichlorido[N,N′‐(cyclohexane‐1,2‐diylidene)bis(4‐fluorobenzohydrazide)‐κ2N,O]zinc(II), [ZnCl2(C20H18F2N4O2)], ( 1 ), and dichlorido[N,N′‐(cyclohexane‐1,2‐diylidene)bis(4‐fluorobenzohydrazide)‐κ4O,N,N′,O′]mercury(II), [HgCl2(C20H18F2N4O2)], ( 2 ). The organic ligand and its metal complexes are characterized using various techniques: IR, UV–Vis and nuclear magnetic resonance (NMR) spectroscopies, in addition to powder X‐ray diffraction (PXRD), single‐crystal X‐ray crystallography and microelemental analysis. Depending upon the data from these analyses and measurements, a typical tetrahedral geometry was confirmed for zinc complex ( 1 ), in which the ZnII atom is located outside the bis(benzhydrazone) core. The HgII atom in ( 2 ) is found within the core and has a common octahedral structure. The in vitro antibacterial activities of the prepared compounds were evaluated against two different bacterial strains, i.e. gram positive Bacillus subtilis and gram negative Pseudomonas aeruginosa bacteria. The prepared compounds exhibited differentiated growth‐inhibitory activities against these two bacterial strains based on the difference in their lipophilic nature and structural features. 相似文献
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Córdova A Ibrahem I Casas J Sundén H Engqvist M Reyes E 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(16):4772-4784
Hexose sugars play a fundamental role in vital biochemical processes and their biosynthesis is achieved through enzyme-catalyzed pathways. Herein we disclose the ability of amino acids to catalyze the asymmetric neogenesis of carbohydrates by sequential cross-aldol reactions. The amino acids mediate the asymmetric de novo synthesis of natural L- and D-hexoses and their analogues with excellent stereoselectivity in organic solvents. In some cases, the four new stereocenters are assembled with almost absolute stereocontrol. The unique feature of these results is that, when an amino acid is employed as the catalyst, a single reaction sequence can convert a protected glycol aldehyde into a hexose in one step. For example, proline and its derivatives catalyze the asymmetric neogenesis of allose with >99 % ee in one chemical manipulation. Furthermore, all amino acids tested catalyzed the asymmetric formation of natural sugars under prebiotic conditions, with alanine being the smallest catalyst. The inherent simplicity of this catalytic process suggests that a catalytic prebiotic "gluconeogenesis" may occur, in which amino acids transfer their stereochemical information to sugars. In addition, the amino acid catalyzed stereoselective sequential cross-aldol reactions were performed as a two-step procedure with different aldehydes as acceptors and nucleophiles. The employment of two different amino acids as catalysts for the iterative direct aldol reactions enabled the asymmetric synthesis of deoxysugars with >99 % ee. In addition, the direct amino acid catalyzed C(2)+C(2)+C(2) methodology is a new entry for the short, highly enantioselective de novo synthesis of carbohydrate derivatives, isotope-labeled sugars, and polyketide natural products. The one-pot asymmetric de novo syntheses of deoxy and polyketide carbohydrates involved a novel dynamic kinetic asymmetric transformation (DYKAT) mediated by an amino acid. 相似文献
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The Carbon-13 chemical shifts of N-Cinamylidenehexyl, t-butyl and sixteen substituted aryl amines were analysed. The lanthanide induced carbon-13 chemical shifts of the cis and trans of four N-cinamylidene substituted anilines were analysed. The spectra N-cinamylidene hexylamine showed only the trans form. The cis/trans ratio of N-cinamylidene aryl amines increased as the LSR concentration increased. 相似文献