The synthesis and thermal decomposition of Na2(SO4)22H2O in both air and nitrogen are described. The synthesis was performed by two different procedures, but in both cases the same
product was obtained, corresponding to the general formula given above.
The crystals obtained were investigated by methods of X-ray powder diffraction, and chemical and thermal analysis. The differences
in thermal decomposition in air and nitrogen are discussed.
The synthesis of hydroxylammonium uranyl acetate is described. The identity of the synthesized compound was confirmed by chemical and infrared analysis. The intermediates and final products of the thermal decomposition were identified by means of thermogravimetric analysis, differential thermal analysis and X-ray diffraction. The thermal decomposition of hydroxylammonium uranyl acetate involves several steps. Two of them are due to decomposition of this compound to UO2 via UO2(CH3COO)2, and the third to the partial oxidation of UO2 to UO3 and the formation of U2O8 in the solid state at higher temperature.
Authors:V. Pet’kov, E. Asabina, A. Markin, and N. Smirnova
Data on synthesis, thermal behavior and thermodynamic properties for the NZP phosphates NaMe2(PO4)3 and Na5Me(PO4)3 (Me=Ti, Zr, Hf) are reported. The compounds were synthesized by sol-gel method and solid-state reactions and characterized by
X-ray powder diffraction, IR spectroscopy, electron microprobe and chemical analysis. Their thermal behavior was studied by
the DTA measurements. The heat capacities of the phosphates were measured between temperatures 7 and 650 K. The fractal dimensions
for the phosphates were calculated. The obtained thermodynamic characteristics of these phosphates and also literature data
for the compounds of NZP type structure are summarized.
Authors:O. Temiz-Arpaci, B. Eylem Cifcioglu Goztepe, Fatma Kaynak-Onurdag, Selda Ozgen, Fatma Senol, and I. Erdogan Orhan
Akbay, A., Oren, I., Temiz-Arpacı, O., Akı-Şener, E., Yalçin, I. (2003) Synthesis and HIV-1 Reverse Transcriptase Inhibitor activity of some 2,5,6-substituted benzoxazole, benzimidazole, benzothiazole and oxazolo(4,5-b)pyridine derivatives. Arzneim
The paper presents a new, nonconventional method, based upon coprecipitation, for the synthesis of niobium oxidic compounds.
The coprecipitation product of niobic acid with calcium oxalate was used as precursor. Calcium metaniobate was obtained by
appropriate thermal treatment of the coprecipitate. The coprecipitation mechanism was studied and the optimal conditions for
quantitative precipitation of niobium and calcium were established. The mechanism of thermal decomposition of the coprecipitate
was investigated by means of differential thermal analysis and X-ray powder diagrams. The final product of thermal decomposition,
calcium metaniobate, is formed at 730°C.
Authors:Piotr M. Korczyk, Monika E. Dolega, Slawomir Jakiela, Pawel Jankowski, Sylwia Makulska, and Piotr Garstecki
Conducting reactions in droplets in microfluidic chips offers several highly attractive characteristics, among others, increased yield and selectivity of chemical syntheses. The use of droplet microfluidic systems in synthetic chemistry is, however, hampered by the intrinsically small throughput of micrometric channels. Here, we verify experimentally the potential to increase throughput via an increase of the scale of the channels.We use the results of these experiments characterizing the processes of (1) generation of droplets, (2) mixing in droplets, (3) inter-phase extraction, and (4) the yield of synthesis of pyrrole, to postulate a number of guidelines for scaling up the throughput of microfluidic droplet systems. In particular, we suggest the rules for maximizing the throughput via an increase of the size of the channels and via parallelization to optimize the throughput of synthesis against the cost of fabrication of the chips and against the kinetic requirements of specific reactions.
The study presents results of examination on Na0.5Bi0.5TiO3 (NBT) ferroelectric synthesis through intermediate binary compound Bi4Ti3O12 (BIT). The first stage of the study related to obtaining BIT from oxide precursors, i.e. Bi2O3 and TiO2. The second stage included obtaining NBT from Bi4Ti3O12, Na2CO3 and TiO2. Two polymorphic modifications of TiO2 (anatase, rutile) and diversified initial homogenization of raw material batches were applied during examination.