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231.
232.
Russian Journal of General Chemistry - Some novel (E)-2-cyano-3-(substituted phenyl/dimethylamino)-N′-[1-(pyren-3-yl)]acrylohydrazides and benzochromenone-2-carbohydrazide derivatives were... 相似文献
233.
Hesham Fahmy Jordan K. Zjawiony Sherief Khalifa Frank R. Fronczek 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(2):o85-o87
The title molecule, 2(R)‐[(1E,3E,7S,8S,11E,13R)‐13‐hydroxy‐4,8,12‐trimethyl‐7,8‐epoxycyclotetradeca‐1,3,11‐trien‐1‐yl]propane‐1,2‐diol, C20H32O4, is a semi‐synthetic analog of sarcophine, the natural cembranoid of marine origin, isolated from the soft coral Sarcophyton glaucum. The conformation of the 14‐membered ring differs substantially from that of sarcophine. The two OH groups of the propane‐1,2‐diol moiety form an unusual weak intramolecular hydrogen bond with an O⋯O distance of 2.788 (2) Å, and the molecules are linked into double chains by intermolecular hydrogen bonds with O⋯O distances of 2.772 (2) and 2.849 (2) Å. 相似文献
234.
235.
Fast Grey RA has been applied as the chromogenic agent for the photometric assessment of copper in the skeletal system of the Egyptian camel (Camelius dromedarius), with amounts of copper as low as 4 to 10 ng determinable. In the preferred procedure, dry ashing and solution in acid are followed by separation of calcium as insoluble calcium sulfate. The copper content of the bones of the camel ranges from 1.1 to 5.6 ppm, dry basis. The procedure should be broadly applicable to mammalian bone. 相似文献
236.
N. El-Said A. Mekhail S. M. Khalifa H. F. Aly 《Journal of Radioanalytical and Nuclear Chemistry》1996,208(1):243-255
Selective efficient method have been for separation of palladium by strong basic anion exchangers IRA-410 and IRA-900 from intermediate radioactive nitrate medium. The different conditions for exchange behaviour of palladium from [ILLW] solutions containing numbre of elements were investigated by batch technique. Selective recovery of palladium from the [ILLW] solution was achieved using column technique. The elution of palladium was carried out via reduction with formic acid where the rate of the reduction process was increased by decreasing the formic acid concentration till 50% followed by dissolving the separated palladium by nitric acid. 相似文献
237.
238.
Summary Solochrome Black P.V. has proved to be a suitable metallochromic indicator in direct titrations of Mg, Zn, Cd and MnII with EDTA or in back titrating Pb, M and Co at pH 10. By its aid together with the application of masking agents as potassium cyanide and ammonium fluoride and the mercuric nitrate procedure, fifteen binary mixtures were analysed using simple procedures which gave precise, reproducible and highly accurate results. It can be used as a substitute for Eriochrome Black T in determining micro and milligram amounts of the above mentioned cations.Part I: Khalifa, H., and S. W. Bishra: Z. analyt. Chem. 183, 108 (1961). 相似文献
239.
The ternary purple coloured complex formed between Th(4+), bromocresol orange (BCO) and cetylpyridinium bromide (CPB) in acidic medium was investigated spectrophotometrically. Results obtained revealed the formation of 1:1:1, Th:BCO:CPB complex in aqueous solution at pH approximately 0.5 with a logarithmic conditional stability constant of 12.04+/-0.1, I=0.1 at 25 degrees C. The colour of the ternary complex was used for the determination of thorium(IV) in the range of 0.02-2.6 mug ml(-1) Th(4+), =9.2x10(4) l mol(-1) cm(-1) at 560 nm. Beside its high sensitivity, the reaction was also proved to be highly selective for Th(4+). Thorium(IV) was determined in presence of great number of transition metal ions, rare earths and different anions. Th(4+) was also determined with high accuracy and precision by its titration with disodium ethylenediaminetetraacetate (Na(2)EDTA) using BCO as an indicator at pH approximately 0.5. The endpoint was detected either visually or spectrophotometrically (lambda=550 nm). The proposed procedures were successfully applied for the determination of Th(4+) in standard Th-U ores and in a series of naturally occurring ores or minerals containing thorium. A spectrophotometric method was also described for the determination of fluoride ion, which was based upon the decrease in colour intensity of the Th-BCO complex on mixing it with F(-) ion. The proposed method was convenient, rapid and sensitive for fluoride. It could be used for the determination of fluoride ion in the 0.02-3.00 mug ml(-1) range (S.D.+/-0.9%). The proposed method was successfully applied for direct determination of F(-) ion in water obtained from different origins and the results were satisfactory. 相似文献
240.
el-Asmy AA Khalifa ME Rakha TH Hassanian MM Abdallah AM 《Chemical & pharmaceutical bulletin》2000,48(1):41-44
Complexes of several transition metal ions with alpha-oximinoacetoacetyl pyridine-4-phenylthiosemicarbazone (H3OAPT) have been prepared. Attempts were made to elucidate their geometries by elemental analysis, molar conductance, magnetic measurements and by some spectroscopic (IR, ESR and electronic) techniques. All the investigated metal ions form mononuclear complexes except for CuII, which forms mononuclear and trinuclear complexes with its chloride and acetate salts, respectively. The IR spectra show that the ligand behaves as a mono or binegative tridentate. Moreover, it acts as a trinegative hexadentate in the trinuclear CuII complex. The protonation constants (logK1H = 9.9 and log K2H = 6.0), as well as the stability constants of the metal complexes, are determined by the pH-titration of H3OAPT and its metal(II) complexes against 0.01 M NaOH. CuII complexes possess square-planar stereochemistry while CoII and NiII have an octahedral one. The crystal field parameters of CoII and NiII complexes are evaluated. 相似文献