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51.
Dwayne R. Senn 《Journal of polymer science. Part A, Polymer chemistry》1994,32(6):1175-1183
Random copoly(p-phenylene sulfide sulfone/ketone)s (PPSS/K) are prepared in high yield by the polycondensation of sodium hydrosulfide (NaSH) with bis(4-chlorophenyl) sulfone (BCPS) and 4,4′-dichlorobenzophenone (DCBP). The polymerization is conducted between 200–220°C, depending on the composition of the copolymer, and in the presence of water without any detrimental effects to the molecular weight. The copolymers with sulfone/ketone mole ratios (S : K) > 25 : 75 are amorphous, while the copolymers with S : K ratios ≤ 25 : 75 are crystalline. These materials form tough, creaseable films and exhibit a linear increase in the glass transition temperature with increasing sulfone content. Sulfuric acid solutions of the copolymers are dark orange to red and display an increasing λmax in the uv-visible spectra as the S:K ratio of the copolymers decreases. © 1994 John Wiley & Sons, Inc. 相似文献
52.
The equilibrium of the heterogeneous reaction between dissolved sodium sulfide and biologically produced sulfur particles has been studied. Biologically produced sulfur was obtained from a bioreactor of a hydrogen sulfide removal process in which the dominating organism is Thiobacillus sp. W5. Detailed knowledge of this reaction is essential to understand its effect on the process. The results were compared with the equilibrium of the reaction of sulfide with ‘inorganic’ elemental sulfur. The equilibrium between dissolved sodium sulfide and biologically produced sulfur particles can be described by an equilibrium constant, Kx, which consists of a weighted sum of constants for polysulfide ions of different chain length, rather than a true single equilibrium constant. For biologically produced sulfur pKx = 9.10 ± 0.08 (21 °C) and 9.17 ± 0.09 (35 °C) with an average polysulfide chain length x = 4.91 ± 0.32 (21 °C) and 4.59 ± 0.31 (35 °C). The pKx value for biologically produced sulfur is significantly higher than for reaction of dissolved sodium sulfide with inorganic sulfur (pKx = 8.82; 21 °C). This difference is probably caused by the negatively charged polymeric organic layer, which is present on biologically produced sulfur but absent with “inorganic” sulfur. Specific binding of polysulfide ions to the organic layer results in a higher polysulfide concentration at the reaction site compared to the bulk concentration. This results in an apparent decrease of the measured equilibrium constant, Kx. 相似文献
53.
Monperrus M Tessier E Veschambre S Amouroux D Donard O 《Analytical and bioanalytical chemistry》2005,381(4):854-862
A robust method has been developed for simultaneous determination of mercury and butyltin compounds in aqueous samples. This method is capable of providing accurate results for analyte concentrations in the picogram per liter to nanogram per liter range. The simultaneous determination of the mercury and tin compounds is achieved by species-specific isotope dilution, derivatization, and gas chromatography–inductively coupled plasma mass spectrometer (GC–ICP–MS). In derivatization by ethylation and propylation, reaction conditions such as pH and the effect of chloride were carefully studied. Ethylation was found to be more sensitive to matrix effects, especially for mercury compounds. Propylation was thus the preferred derivatization method for simultaneous determination of organomercury and organotin compounds in environmental samples. The analytical method is highly accurate and precise, with RSD values of 1 and 3% for analyte concentrations in the picogram per liter to nanogram per liter range. By use of cleaning procedures and SIDMS blank measurements, detection limits in the range 10–60 pg L–1 were achieved; these are suitable for determination of background levels of these contaminants in environmental samples. This was demonstrated by using the method for analysis of real snow and seawater samples. This work illustrates the great advantage of species-specific isotope dilution for the validation of an analytical speciation method—the possibility of overcoming species transformations and non-quantitative recovery. Analysis time is saved by use of the simultaneous method, because of the use of a single sample-preparation procedure and one analysis. 相似文献
54.
V. A. Startseva L. E. Nikitina N. P. Artemova S. A. Dieva V. V. Plemenkov 《Chemistry of Natural Compounds》2000,36(6):587-589
Ethanedithiol and di(mercaptoethyl)sulfide react regio- and stereoselectively with (+)-3-carene and -hydroxy(-)--pinene -oxides in the presence of sodium ethoxide to give the corresponding bis- and tris-sulfides with two terpene fragments 相似文献
55.
C.?Buron C.?Filiatre F.?Membrey A.?FoissyEmail author J.?F.?Argillier 《Colloid and polymer science》2004,282(5):446-453
The interaction between sodium dodecyl sulphate (SDS) and gelatin was studied at pH 4.5 and 6.5 where the gelatin is positively charged (i.e.p. 8). At pH 4.5 a SDS/gelatin concentration range was found where gelatin precipitates. At pH 6.5 the SDS-gelatin complex remains soluble although three SDS concentration domains were distinguished where the SDS-gelatin complex had very different affinities for the solvent. Below C1 the complex was highly surface active but other measurements (viscosity, potentiometry, protons uptake) did not reveal any particular consequence of binding. Between C1 and C2 the molecular size decreased (viscosity lowering) upon charge neutralization and collapse about small SDS aggregates (17 SDS molecules per gelatin molecule). Above C2 a cooperative binding mechanism lead to the formation of SDS aggregates; the complex stretched out and turned strongly hydrophilic (the viscosity increases, low surface activity). At saturation one gelatin molecule bound about 200 SDS molecules. Above the overlap concentration (about 3 wt%) SDS aggregates formed between several gelatin molecules, the viscosity increased continuously with SDS concentration and the binding ratio was lower than in dilute gelatin solutions. A very good correspondence was found between the different analytical data including turbidity, viscosity, surface tension, protons uptake and direct potentiometric SDS binding measurements. 相似文献
56.
重氮树脂与十二烷基硫酸钠相互作用研究罗杨磊曹维孝(北京大学化学与分子工程学院北京100871)关键词重氮树脂,十二烷基硫酸钠,负性PS版随着化学与生命科学领域的发展,大分子与小分子在溶液的相互作用越来越受到关注.表面活性剂因其具有自组装能力,... 相似文献
57.
58.
The reaction of [SiMe2(C5H4)2][(C5Me5)ZrMe2]2 with H2S at 110°C proceeds with the formation of [SiMe2(C5H4)2][(C5Me5)Zr(-S)]2]2. The molecular structure of this dinuclear zirconocenophane compound features a non-planar four-membered Zr2(-S)2
2 ring with two symmetrically-bridging sulfido groups. The bridging dimethylsilyl-bridged bis(cyclopentadienyl) ligand adopts a skewed orientation to accommodate the long Zr ... Zr separation of 3.611(1) Å. This compound crystallizes in the centrosymmetric space group P1 with refined lattice parameters ofa = 10.905(1) Å,b = 10.939(2) Å,c = 14.621(2) Å, = 106.32(1)°, = 91.25(1)°, = 111.25(1)°,V = 1545.1(8) Å3, calc. = 1.512g/cm3,Z=2. Full-matrix refinement converged with final discrepancy indices of R(F
o = 0.045 andR(F
o) = 0.079 with GOF= 1.60 for 4403 data withF
o > 3(F
o).This paper is dedicated to Professor Larry Dahl, a valued friend and mentor, on the occasion of his 65th birthday and in recognition of his significant fundamental contributions to the field of metal cluster chemistry. May the Goddess Fortuna continue to bring distinction and honor to him and his research endeavors. 相似文献
59.
T. Yamamoto A. Taniguchi S. Dev E. Kubota K. Osakada K. Kubota 《Colloid and polymer science》1991,269(10):969-971
Organosols of NiS, PdS, and MnS in N,N-dimethylformamide were prepared by reaction of the metal acetate with H2S. Organosols of mixed-metal sulfides (Zn
x
Cd1–x
S, Hg
x
Cd1–x
S, Hg
x
Cu1–x
S, Cd
x
Mn1–x
S, Hg
x
Mn1–x
S, Hg
x
Cd1–x
S, and Mn
x
Zn1–x
S) were similarly obtained by reaction of mixtures of the metal salts with H2S. The organosol of Zn0.5Cd0.5S contained particle with two particle size distributions centered at 6.5 nm and 29 nm, as revealed by Ar laser-scattering analysis. The metal sulfides are recovered by addition of Et2O to the organosols. Zn
x
Cd1–x
S thus obtained shows magnetic susceptibility in the range 0.5×10–6–2.3×10–6 emug–1 depending on thex value. Addition of polymers to the organosols affords semiconducting films of metal sulfide-polymer composites. 相似文献
60.
离子选择电极—流动注射分析法动力学测定葡萄糖存在下的果糖 总被引:3,自引:0,他引:3
本文将离子电极与流动注射分析相结合,利用30℃下,在强碱性介质中,果糖和葡萄糖与2,4-二硝基酚钠反应速度明显差异,动力学测定了葡萄糖存在下果糖的含量。自制了2,4-二硝基酚电极作为动力学电位测定用的工作电极。本法测定果糖的范围为0.02~1.00mol/L,其RSD为4.0%~4.9%,RE为1.0~5.0%;当C葡/C果≤3倍时,葡萄糖的干扰不超过5%;本法也曾成功地用于果葡萄浆测定,其RSD 相似文献