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1.
Quantitative DTA results are presented for the phase changes in some cadmium and zinc n-alkanoates. Cadmium carboxylates form liquid crystal phases. The total entropy of the solid-to-liquid transition is small indicating a high degree of aggregation in the isotropic liquid. The phases previously reported by Skoulios are shown to be due to the presence of basic carboxylates. The zinc carboxylates have solid—solid transformations but do not form liquid crystal phases. The entropies of fusion are of the same order as those in the lead salts showing only a small degree of aggregation in the liquid. 相似文献
2.
The 23Na NMR lineshapes are reported for the ionic mesophase and isotropic phase of the melts of sodium n-butyrate and sodium isovalerate. The powder pattern for the central transition typical for the second-order quadrupole effect observed in the mesophase melts is of particular interest. Some analogies to 23Na behavior in sodium β-alumina are pointed out. 相似文献
3.
We have studied the thermal stabilities of the alkali metal trifluoroacetates by means of DTA and TG, and shown that they are stable in the solid form, with the exception of the lithium salt. We have determined the enthalpies of melting of these five salts. We have also studied the kinetics of decomposition of CF3COONa, of CF3COOK and of their mixture. This decomposition is in all cases of the first order. The mixture decomposes in two steps, the first one corresponding to the decomposition of the sodium salt.
We are grateful to Miss H. Lartigue for technical assistance. Thanks are due to Prof. A. Buchs, Director of the Mass-spectrometry Laboratory. 相似文献
Zusammenfassung Die ThermostabilitÄt der Alkalitrifluoracetate wurde durch DTA und TG untersucht und festgestellt, da\ diese in der festen Form mit Ausnahme des Lithiumsalzes stabil sind. Die Schmelzenthalpie dieser fünf Salze wurde bestimmt. Die Kinetik der Zersetzung von CF3COONa, CF3COOK und ihrer Gemische wurde ebenfalls untersucht. Diese Zersetzung ist in allen FÄllen ein Vorgang erster Ordnung. Die Gemische werden in zwei Stufen zersetzt, wobei die erste Stufe der Thermolyse des Natriumsalzes entspricht.
Résumé Nous avons étudié la stabilité thermique des trifluoroacétates alcalins par ATD et TG, et montré que seul le sel de lithium se décompose avant la fusion. Nous avons déterminé les enthalpies de fusion de ces cinq sels. Nous avons également étudié la cinétique de décomposition de CF3COONa, CF3COOK et de leurs mélanges. Cette décomposition est dans tous les cas d'ordre 1. Les mélanges se décomposent en deux étapes, la première correspondant à la thermolyse complète du sel de sodium.
. , . , . CF3COOK, CF3COONa . . , .
We are grateful to Miss H. Lartigue for technical assistance. Thanks are due to Prof. A. Buchs, Director of the Mass-spectrometry Laboratory. 相似文献
4.
The CF3COOK-CF3COONa phase diagram was studied by DTA between 100% and 50 wt. % CF3COOK; the thermal decomposition of CF3COONa-rich samples prevents the complete determination of the phase diagram. Two eutectics were found:E
1 at 89.5 wt. % CF3COOK andE
2 at 62 wt. %, with melting points at 122–123 and 112–113, respectively, representing a temperature approximately 30 lower than the m. p. of pure CF3COOK (140.5). The presence of a compound between these two eutectics is not formally established, but is probable at about 85 or 87 wt. % CF3COOK, melting at 124–125. DTA has shown that the fused mixtures solidify into a metastable state, the phase diagram of which presents a labile eutectic at 75 wt. % CF3COOK, melting at 88.
This paper is based on part of the Dissertation (No. 1721) of R. Dallenbach, University of Geneva.
Thanks are due to Professor R. Monnier and Dr. J. J. Duruz for useful discussions. 相似文献
Zusammenfassung Das CF3COOK-CF3COONa Phasendiagramm wurde mittels DTA, zwischen 100 und 50 Gew. % CF3COOK untersucht; die thermische Zersetzung CF3COONa-reicher Proben macht die Bestimmung des vollständigen Phasendiagramms unmöglich. Zwei Eutektika wurden gefunden:E 1 bei 89.5 Gew. % CF3COOK undE 2 bei 62 Gew. %, mit den entsprechenden Schmelzpunkten bei 122–123 und 112–113, welche bei um etwa 30 niedrigeren Temperaturen liegen als der Schmelzpunkt des reinen CF3COOK (140.5). Die Existenz einer Verbindung zwischen diesen beiden Eutektika wurde zwar nicht genau bewiesen, sie liegt aber wahrscheinlich bei etwa 85 oder 87 Gew. % CF3COOK und schmilzt bei 124–125. Mittels der DTA konnte nachgewiesen werden, daß die geschmolzenen Gemische in einen metastabilen Festkörperzustand übergehen, dessen Phasendiagramm ein labiles Eutektikum bei 75 Gew. % CF3COOK mit einem Schmelzpunk bei 88 aufweist.
Résumé Le diagramme de phases CF3COOK-CF3COONa a été établi par ATD entre CF3COOK et le mélange à 50% poids; la décomposition thermique des échantillons riches en CF3COONa empÊche la détermination complète du diagramme de phases. On observe deux eutectiques:E 1 à 89.5 % poids en CF3COOK etE 2 à 62% poids, fondant respectivement à 122–123 et 112–113, ce qui représente un abaissement d'environ 30 C par rapport au P. F. de CF3COOK pur (140.5). L'existence d'un composé entre ces deux eutectiques n'a pu Être montrée formellement. Il se situe vraisemblablement vers 85 ou 87 % poids en CF3COOK et fond à 124–125. L'ATD a montré que les mélanges fondus se solidifient dans un état métastable, dont le diagramme de phases présente un eutectique labile à 75% poids en CF3COOK fondant à 88.
CF3COOK—OF3COONa CF3COOK 100 50 .%. CF3COONa, . :E 1 CF3COOK 89,5 .% 2-62 .% 122–123 112–113, 30 , . . CF3COOK (140,5). , , , CF3COOK 85 87 .% 124–125. , , CF3COOK 75 .% 88.
This paper is based on part of the Dissertation (No. 1721) of R. Dallenbach, University of Geneva.
Thanks are due to Professor R. Monnier and Dr. J. J. Duruz for useful discussions. 相似文献
5.
L. P. Burleva V. M. Andreev V. V. Boldyrev 《Journal of Thermal Analysis and Calorimetry》1988,33(3):735-739
The thermal decompositions of the even silver dicarboxylates from silver oxalate to silver sebacate were studied. In vacuum, the dicarboxylates decomposed to give metallic silver, CO2 and organic diradicals as primary products, and polymers as secondary products. The higher silver dicarboxylates were much more stable to thermal treatment than silver oxalate, probably due to the initiation of decomposition of all carboxylates except silver oxalate by the rupture of a Ag-O and not a C-C bond.
Zusammenfassung Die thermische Zersetzung der geradzahligen Silberdicarboxylate Silberoxalat bis-sebacinat wurde untersucht. Unter Vakuum zersetzen sich die Dicarboxylate zu metallischem Silber, CO2 und organischen Diradikalen als Primärprodukt und Polymeren als Sekundärprodukt. Die höheren Silberdicarboxylate sind wesentlich stabiler als das Oxalat, wahrscheinlich weil bei ihnen die Zersetzung von der Spaltung einer Ag-O-Bindung und nicht einer C-C-Bindung wie beim Oxalat ihren Anfang nimmt.
, . , — . , . , , , Ag-O, -.相似文献
6.
Mario Bianchi Piero Frediani Ugo Matteoli Gloria Menchi Franco Piacenti Giorgio Petrucci 《Journal of organometallic chemistry》1983,259(2):207-214
The behaviour of the [Ru2(CO)4(CH3COO)2]n/tributylphosphine/acetic acid system has been investigated as a function of reaction conditions and molar ratios of reactants. Tricyclohexylphosphine and triethylphosphite were also used as ligands and investigation was extended to the related oxalic, malonic, succinic, glutaric and adipic acid derivatives. These derivatives were isolated and characterized in view of their possible role as catalysts in the homogeneous hydrogenation of carboxylic acids in the presence of phosphine- or phosphite-substituted ruthenium carbonyl derivatives. 相似文献
7.
Energy transfer processes affecting the luminescence properties and methods of controlling them by a change in the compositions and structures of luminescent compounds are analyzed in the review on example of lanthanide aromatic carboxylates. The analysis demonstrates clearly how the understanding of the physical regularities of the processes leading to luminescence makes it possible to perform the purposeful design of organic ligands and their brightly luminescing complexes with lanthanides. 相似文献
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10.
Thermal decomposition of anhydrous Cu(HCOO)2 (1) affords H2, CO, CO2, H2O, HCuOOH, CuHCOO, Cu, and the polymeric product, which contains -CH2O,-C(O)OH-, and -RCH-0- groups. Dccomposition of1 proceeds in stages with formation of copper(I) formate as an intermediate. Possible pathways of decomposition ofI, including isomeric forms of the HCO2 radical as intermediates, were analyzed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1406–1412, June, 1996. 相似文献
11.
Metal carboxylates with open architectures 总被引:6,自引:0,他引:6
Rao CN Natarajan S Vaidhyanathan R 《Angewandte Chemie (International ed. in English)》2004,43(12):1466-1496
The field of inorganic open-framework materials is dominated by aluminosilicates and phosphates. The metal carboxylates have emerged as an important family in the last few years. This family includes not only mono- and dicarboxylates of transition, rare-earth, and main-group metals, but also a variety of hybrid structures. Some of the carboxylates possess novel adsorption and magnetic properties. Dicarboxylates and related species provide an effective means of designing novel hybrid structures with porous and other properties. In some of these structures, the dicarboxylate acts as a linker between two inorganic units. Hybrid nanocomposites are also of particular note, for example, cadmium oxalate host lattices that can accommodate extended alkali-metal halide structures. This Review discusses the synthesis, structure, and properties of various types of open-framework metal carboxylates. 相似文献
12.
Dynamics of changes in microstresses during thermal decomposition of Cu(HCOO)2 crystals and their effect on the thermal decomposition kinetics were studied by IR spectroscopy at 105 to 120 °C. The formation of solid intermediate HCOOCu was observed, and the dynamics of its accumulation was followed. Kinetic regularities of transformation of HCOO groups were compared with those for gas evolution.For Communication 1, see Ref. 1.Translated from Izvestiya va Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 350–354, February, 1996. 相似文献
13.
Thermal solid-phase decomposition of anhydrous copper(ii) formate has been studied at 120–180 ° The rate of gas evolution during the decomposition depends on the depth of conversion and can be presented as the sum of first-order reaction rates and the rate of the autocatalytic process (a second-order reaction). The evolution of the solid phase during thermolysis has been observed by optical microscopy. The decomposition of copper formate is a complex topochemical process, a combination of homogeneous and heterogeneous transformations and dispersion of large crystals.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. l, pp. 72–76, January, 1996. 相似文献
14.
I. V. Kalinovskaya A. N. Zadorozhnaya Yu. M. Nikolenko V. E. Karasev 《Russian Journal of Inorganic Chemistry》2006,51(3):457-461
Mixed-ligand binuclear and mononuclear europium carboxylate complexes with nitrogen-and phosphorus-containing neutral ligands have been studied by luminescence and X-ray photoelectron spectroscopy. The coordination of neutral ligands through the nitrogen donor atom leads to an increase in electron density at the Eu3+ atom. In groups of carboxylates of the same type, the coordination of neutral donor ligands leads to an increase in the relative intensity of the 5 D 0-7 F 4 electric dipole transition. Analysis of the luminescence excitation spectra points to the presence of two excitation energy transfer channels for mixed-ligand europium trifluoroacetate and toluate complexes and of one channel for europium cinnamate complexes with neutral ligands. 相似文献
15.
A. A. Nikonorov E. S. Ostroglyadov O. S. Vasil’ev V. M. Berestovitskaya 《Russian Journal of General Chemistry》2011,81(8):1681-1690
3-Methoxycarbonyl-4-phenyl- and 4-(3-pyridyl)-2-pyrrolidones react with 2-aryl(heteryl)-1-nitroethenes to form C3-adducts as one or two diastereomers. Their structure was characterized by the IR, 1H, and 13C NMR spectroscopy, using the two-dimensional correlation spectroscopy. 相似文献
16.
Boronate ureas operate as catalysts for the activation of nitrocyclopropane carboxylates in nucleophilic ring-opening reactions. A variety of amines were found to open the urea-activated nitrocyclopropane carboxylates, generating highly useful nitro ester building blocks in good yields. Standard manipulations allow access to a wide range of valuable compounds from the ring-opened products with direct applications in bioactive target synthesis. 相似文献
17.
Benoît Moreau Dino Alberico Vincent N.G. Lindsay André B. Charette 《Tetrahedron》2012,68(17):3487-3496
A Cu(I)-catalyzed asymmetric cyclopropanation of alkenes with an iodonium ylide has been developed. The copper source, hypervalent iodine source, solvent, and additives all have a significant effect on the yields and enantioselectivities. High enantioselectivity (up to 99:1 er) and diastereoselectivity (95:5 dr trans/cis) were achieved for a wide range of alkenes. Conditions were developed to convert the trans products to the cis isomers. In addition, 1-nitrocyclopropyl carboxylates were transformed into the corresponding substituted cyclopropane amino acids and aminocyclopropanes. Moreover, a comparative study between Zn- and In-mediated reduction reactions of the nitro group in these compounds with regards to the er erosion in the process is also documented. 相似文献
18.
Measurements have been made of the temperatures and enthalpy changes of phase transitions in the systems lead dodecanoate/lead oxide and lead dodecanoate/hendecane. The data have been discussed in terms of the R theory of amphiphylic mesophases. The concepts of the R theory are shown to be useful in the interpretation of phase transitions in molten carboxylate systems. 相似文献
19.
Gardimalla HM Mandal D Stevens PD Yen M Gao Y 《Chemical communications (Cambridge, England)》2005,(35):4432-4434
Candida rugosa lipase immobilized on maghemite nanoparticles demonstrated high stereoselectivity in kinetic resolution of racemic carboxylates and improved long-term stability over its parent free enzyme, allowing the supported enzyme to be repeatedly used for a series of chiral resolution reactions. 相似文献
20.
We have found a form of copper(II) terephthalate that occluded an enormous amount of gases such as N2, Ar, O2, and Xe. Copper(II) terephthalate is the first metal complex found capable of adsorbing gases. This complex has opened a new field of adsorbent chemistry and is recognized as a leader in the construction of microporous metal complexes. In extending the route for the synthesis of microporous complexes, we obtained many new porous materials that are widely recognized as useful materials for applications in areas such as gas storage, molecular sieves, catalysis, inclusion complexes, and surface science. 相似文献