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251.
Six new derivatized deltahedral Zintl ions have been synthesized by reactions between the known Zintl ions Ge(9) (n-) with the halides R(3)EX and/or the corresponding anions R(3)E(-) for E=Ge or Sn. This rational approach is based on our previous discovery that these derivatization reactions are based on nucleophilic addition to the clusters. All species were structurally characterized as their salts with potassium countercations sequestered in 2,2,2-crypt or [18]crown-6 ether. The tin-containing anions were characterized also in solutions by (119)Sn NMR spectroscopy. The reaction types for such substitutions and the structures of the new anions are discussed. 相似文献
252.
A rapid and reliable high performance liquid chromatographic (HPLC) method for the simultaneous determination of heterocyclic
compounds, namely nicotinic acid, nicotinamide, and 3-cyanopyridine, in industrial effluent is described. A Φ4.6 mm × 150
mm, 5 μm C-18 reversed phase stationery phase, and a methanol-acetonitrile-water tertiary mobile phase (20:20:60 v/v) were
used for separation. The detection wavelength of a diode array (DAD) was set at 216 nm with a bandwidth of 16 nm. Phenol was
used as an internal standard. The regression equations revealed a linear relationship between the concentration of the analytes
injected and the peak area detected by DAD. The limits of detection (S/N = 3) ranged from 0.70 to 1.18 mg L−1, the recoveries ranged from 87% to 102% and the precision expressed as % RSD intra-day and inter-day varied from 0.9 to 3.9
and 1.2 to 5.6, respectively. This method is rapid, sensitive and suitable for the monitoring of nicotinic acid, nicotinamide,
and 3-cyanopyridine in effluent of related pharmaceutical manufacturing plants. 相似文献
253.
本文对一类重要的ⅥB族金属叁键化合物R_2M_2(CO)_4(R为环戊二烯基及类环戊二烯基)近年来的研究成果进行了综述,综述重点是这类化合物的官能团M≡M参键的化学活性,全文包括R_2M_2(CO)_4的合成及结构,M≡M叁键与亲核试剂、与碳-碳重键,与氧或与金属羰基物等试剂的反应及其应用。 相似文献
254.
本文报道了三种聚苯乙烯支载苯并-15-冠-5与两种聚苯乙烯支载无环冠醚的合成,并研究了它们对K~+与Na~+的络合性能与相转移催化性能。 相似文献
255.
Dilithiated N,N′‐dimethyl‐piperazine, LiCH2N(CH2CH2)2 NCH2Li ( 2 ) was prepared by transmetallation of N,N′‐bis(trimethylstannylmethyl)‐piperazine ( 1 ) with nBuLi and was isolated as a highly pyrophoric yellowish powder in high yield. Compound 2 was characterized by elemental analysis and was reacted as difunctional aminomethylating reagent with dialkyl‐earth metal chlorides, R2MCl (M = Al, Ga; R = Me, tBu) which resulted in the formation of spirocyclic adducts of N,N′‐bis(dialkylmetallamethyl)‐piperazine and unreacted dialkylmetal chlorides, [(Me2AlCl)Me2AlCH2N(CH2CH2)2NCH2AlMe2(ClAlMe2)] ( 3 ) and [(tBu2GaCl)tBu2GaCH2N(CH2CH2)2NCH2GatBu2(ClGatBu2)] ( 4 ) with five‐membered rings. Compounds 1 , 3 and 4 were identified by NMR‐spectroscopy (1H, 13C, 119Sn for 1 , 27Al for 3 ), mass spectra (EI, for 1 ) and by crystal structure determinations. 相似文献
256.
Stella C Galland A Liu X Testa B Rudaz S Veuthey JL Carrupt PA 《Journal of separation science》2005,28(17):2350-2362
An RPLC was developed to rapidly determine lipophilicity of neutral and basic compounds using three base deactivated RPLC stationary phases particularly designed for the analysis of basic compounds, namely, Supelcosil ABZ(+)Plus, Discovery RP Amide C16, and Zorbax Extend C18. The work consisted of three sets of experiments. In the first log kw values of neutral compounds were extrapolated using hydroorganic mobile phases at different compositions. Good correlation between log kw and log Poct indicated that the method was appropriate for these supports, without adding a silanol masking agent. In the second set of experiments, isocratic log k values of neutral and basic compounds were measured with three different mobile phases. The best estimation of lipophilicity was obtained for neutral and basic compounds when the secondary interactions were strongly reduced (i. e., when basic compounds were under their neutral form). In the third set of experiments, isocratic retention factors of basic compounds (in their neutral form) were measured with a high-pH mobile phase, on a chemically stable support (Zorbax Extend C18). Under these chromatographic conditions, correlation between the isocratic retention factors and log Poct (log D10.5) for basic compounds was similar to that for neutral compounds. 相似文献
257.
Shigeru Shimada Osamu Yamazaki Yohichi Suzuki 《Journal of organometallic chemistry》2004,689(19):3012-3023
Hypervalent organobismuth compounds, 6-tert-butyl-5,6,7,12-tetrahydrodibenz[c,f][1,5]azabismocines, with 13 different substituents on the bismuth atom including halogens, alkyl, alkenyl, alkynyl, aryl, or phenylthio groups have been synthesized. A key compound, 12-chloro-6-tert-butyl-5,6,7,12-tetrahydrodibenz[c,f][1,5]azabismocine, which is a precursor for other azabismocines, has been synthesized by two different procedures; one is based on Akiba’s method using 2-bromobenzylbromide as one of the starting materials and the other is a newly developed one using a cheaper starting material, 2-chlorobenzyl chloride. The structures of 12 new bismuth compounds were determined by X-ray diffraction. The eight-membered tetrahydroazabismocine ring has proved to be highly flexible and the hypervalent Bi-N bond distances vary ranging from 2.568(3) to 2.896(5) Å, depending on the electronic nature of the substituents on the bismuth atom. The Bi-N bond distances have good linear relationship against Hammett’s σm constants. 相似文献
258.
J. M. Bayona J. Grimalt J. Albaigs W. Walker B. W. de Lappe R. W. Risebrough 《Journal of separation science》1983,6(11):605-611
Analyses of hydrocarbon fractions from different areas of the marine environment are described to illustrate the possibilities and limitations of high resolution gas chromatography (HRGC) in the analysis of environmental samples. Examples are given of dissolved, particulate, and sedimentary hydrocarbons and organochlorine compounds; the importance of an adequate sampling of the marine environment is stressed. HR chromatographic profiles obtained in two columns of low and high polarity (SE-52 and PEG 20M) permit the sources and transport pathways of both natural and anthropogenic hydrocarbons to be traced. Analysis of tissues of marine mammals, which metabolize or excrete many of the biogenic and petrogenic hydrocarbons present in other areas of the marine environment, may provide an opportunity to obtain relatively clean profiles of many anthropogenic compounds of interest. The plotting of mass chromatograms from data compiled by COM-GC-MS remains the most appropriate method for the conclusive indentification of these compounds. 相似文献
259.
桥联双(甲巯咪唑)化合物的合成和配位性能 总被引:3,自引:0,他引:3
研究了桥联双(甲巯咪唑)化合物(Ⅰ_a—Ⅳ_a、Ⅰ_b)的合成和配位性能。UV谱显示Ⅰ_a—Ⅳ_a与UO_2~(2+)离子(硬酸)配位,溶液中形成3:1的配合物。Ⅰ_b与Hg~(2+)、Au~(3+)离子(软酸)配位形成2:1的配合物,用CNDO/2方法计算了各配体分子中原子净电荷密度和HOMO、LUMO能量。 相似文献
260.