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81.
Reactions of the substituted 2‐formyl chromones with aroylhydrazines gave corresponding 2‐(aroylhydrazonomethylidyne) chromones. Then 2‐(3′‐acetyl‐5′‐aryl‐2′,3′‐dihydro‐1′,3′,4′‐oxadiazol‐2′‐yl) chromones were prepared by these 2‐(aroylhydrazonomethylidyne) chromones under refluxing with Ac2O. All target compounds were characterized through elemental analysis and IR, 1H NMR, MS. 相似文献
82.
Summary A dichrometric procedure has been reported for the direct titration of mercury(I) to an iodine monochloride end point. The concentration of hydrochloric acid must be at least 7.5 N at the end point. 相似文献
83.
A selective analytical extraction method for rapid successive complexometric determination of thorium(IV) and uranium(VI) in sulphuric acid media is described. The method is based on the extraction of thorium and uranium from sulphuric acid media with N-butylaniline or N-benzylaniline in chloroform. Both thorium and uranium are selectively and quantitatively extracted in the presence of ascorbic acid and EDTA. Most cations and anions do not interfere. The reduction of uranium(VI) with sodium dithionite at room temperature is rapid and quantitative and superior to that with ascorbic acid, which reduces uranium(VI) in boiling solution. The method is simple, rapid and accurate, and the experimental conditions are not highly critical. 相似文献
84.
G.B. Song C.Q. Han J.K. Liang Q.L. Liu F.S. Liu G.H. Rao 《Journal of solid state chemistry》2004,177(7):2394-2403
The subsolidus phase relations of the PrOx-CaO-CuO pseudo-ternary system sintered at 950-1000°C have been investigated by X-ray powder diffraction. In this system, there exist one compound Ca10Pr4Cu24O41, one Ca2Pr2Cu5O10-based solid solution, seven three-phase regions and two two-phase regions. The crystal structures of Ca10Pr4Cu24O41 and Ca2Pr2Cu5O10-based solid solution have been determined. Compound Ca10Pr4Cu24O41 crystallizes in an orthorhombic cell with space group D2h20−Cccm, Z=4. Its lattice parameters are a=11.278(2) Å, b=12.448(3) Å and c=27.486(8) Å. The crystal structure of Ca2Pr2Cu5O10-based solid solution is an incommensurate phase based on the orthorhombic NaCuO2 type subcell. The lattice parameters of the subcell of the Ca2.4Pr1.6Cu5O10 are a0=2.8246(7) Å, b0=6.3693(5) Å, c0=10.679(1) Å, and those of the orthorhombic superstructure are with a=5a0, b=b0, c=5c0. The Ca2.4Pr1.6Cu5O10 structure can also be determined by using a monoclinic supercell with space group C2h5−P21/c, Z=4, a=5a0, b=b0, and β=104.79(1)° or 136.60(1)°, V=5a0b0c0. 相似文献
85.
86.
Summary A volumetric method has been developed for the determination of thorium salts with Titriplex III (disodium EDTA) using a mixture of ferrous salt and cacotheline as indicator. The titration of the thorium salt is carried out in a buffered solution ofph 2.72 in carbon dioxide atmosphere with magnetic stirring until a pink color appears. The reduction of cacotheline to the pink compound occurs only when all the thorium is complexed by EDTA. The end point is sharp and the method has been found to give results accurate to 0.2 to 0.3%. Ferric iron, zirconium and phosphates are found to interfere while ferrous iron does not interfere. Walpole sodium acetate-HCl buffers are to be employed since phosphate-citrate buffers interfere, due to the presence of phosphate and citrate.In conclusion one of us, Mr. V. Narayana Rao, desires to express his grateful thanks to the Ministry of Education, Government of India, for the award of Senior Research Fellowship which has enabled him to take part in this investigation. 相似文献
87.
C.N.R. Rao 《Tetrahedron》1976,32(13):1561-1566
Systematics in the ionization energies corresponding to the different π orbitals of para, meta and ortho-disubstituted benzenes obtained from PES have been investigated. The data have been discussed in terms of correlations with substituents constants and such correlations are shown to provide the basis to differentiate steric from electronic effects in the case of ortho derivatives. Ionization energies from PES corresponding to the lone pair orbitals of substituents in related series of p-disubstituted benzenes are shown to vary systematically with the substituent constants. 相似文献
88.
Alkali metal ion—oxygen donor solvent cages as well as coordination compounds, alkali metal oxide glasses and oxyanion salts of alkali metals exhibit low-frequency bands in the infrared spectrum characteristic of the cation—oxygen polyhedra. Similar bands are seen with nitrogen donors. Alkaline earth ions also show such absorption bands due to quantised vibration of cations. These bands not only provide a means of establishing the nature of cation coordination in diverse systems, but also serve as probes to examine ion-solvent interactions. 相似文献
89.
[Chemical reaction: See text] We have developed a general, efficient, and inexpensive catalyst system for arylation of amines by using 10 mol % of CuI as the copper source, 20 mol % of diphenyl pyrrolidine-2-phosphonate (DPP) as the ligand, K3PO4 as the base, and DMF containing 2% water (v/v) as the solvent. 相似文献
90.
P. Govindan A. Palamalai K. S. Vijayan K. Dhamodharan S. Subbuthai S. V. Mohan R. V. Subba Rao 《Journal of Radioanalytical and Nuclear Chemistry》2003,255(3):571-574
A method is developed for the selective leaching of 233U from a thorium oxalate cake. The leaching capacity of ammonium carbonate and nitric acid have been investigated, showing that (NH4)2CO3 leads to higher recovery. The maximum leaching efficiency is obtained using 0.5% ammonium carbonate, with a minimal thorium pick-up. A uranium recovery of 94% is obtained after three consecutive contact experiments in carbonate media, with minimal thorium uptake in the leachate. This process was applied to an actual plant stream, allowing the reduction of the 233U -activity from 5.64 to 0.3 Ci/g of thorium oxalate cake. 相似文献