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941.
Dawson结构钼钒磷杂多化合物对苯酚过氧化氢羟化作用的研究 总被引:14,自引:0,他引:14
Dawson结构钼钒磷杂多化合物对苯酚过氧化氢羟化作用的研究于剑锋,杨宇,吴通好,孙家锺(吉林大学化学系理论化学研究所,长春,130023)关键词Dawson结构钼钒磷杂多化合物,苯酚羟化,过氧化氢苯二酚(DBH)是重要的化工原料.由芳香化合物羟化制... 相似文献
942.
Summary The semi-empirical theory on the retention volume in gas chromatography recently developed by some experiments, was found to require partial correction. It was newly refined and summarized. Overall experimental checking was performed by the use of Cl2, Br2, and I2.
Gas-Chromatographie von Halogenen
Zusammenfassung Die halbempirische Theorie über das Retentionsvolumen in der Gas-Chromatographie, die kürzlich an Hand einiger Versuche entwickelt wurde, erforderte eine teilweise Korrektur. Sie wurde verbessert und zusammenfassend dargestellt. Kontrollversuche wurden mit Hilfe von Chlor, Brom und Jod durchgeführt.相似文献
943.
Zusammenfassung Am Beispiel der Bestimmung von Phenacetin und Coffein im pharmazeutisch verwendeten Mengenverhältnis wird die quantitative in situ-Auswertung eines Zweikomponentensystems im on line-Betrieb: Densitometer—Integrator—Tischrechner beschrieben. Die Eichgerade wird für beide Substanzen auf jeder Platte gesondert bestimmt. Durch eine Einschränkung des Konzentrationsbereichs auf obere und untere Toleranzgrenze ergeben sich Vereinfachungen der Ausgleichsrechnungen. Die erzielten Genauigkeiten liegen bei 2 Analysen pro Platte bei 1,51% (Phenacetin) und 2,56% (Coffein) bzw. bei 4 Analysen pro Platte bei 1,50% (Phenacetin) und 2,64% (Coffein) (rel. gen. Standardabweichung, n=18 bzw. n=36).Der Deutschen Forschungsgemeinschaft danken wir für die großzügige Unterstützung dieser Arbeit durch Sach- und Personalmittel. Frau Koch danken wir für die gewissenhafte Mithilfe bei der praktischen Durchführung der Untersuchungen. 相似文献
944.
A new series of group 6 carbonyl complexes of N-[(2-pyridyl)methyliden]-α (or β)-aminonaphthalene (α/β-NaiPy) are described in this work. The complexes are formulated as cis-[M(CO)4(α/β-NaiPy)] by elemental, mass and other spectroscopic data. The complexes show emission spectra at room temperature and their quantum yield lies between 0.4 and 0.5. All the complexes exhibit negative solvatochromism. Cyclic voltammetry shows metal centred oxidation and ligand reductions. 相似文献
945.
The copolymerization of acrylonitrile (AN) in dimethylformamide (DMF) was retarded by the presence of itaconic acid (IA) comonomer. Addition of TEA helped overcome the retardation at enhanced concentrations of IA in the feed. The monomer reactivity ratios determined by both terminal and penultimate models revealed that the overall monomer reactivity’s are practically unaffected by the presence of TEA. The penultimate-unit effect for radicals terminated in AN was enhanced by the presence of TEA. Higher TEA concentrations helped regain the reactivities of AN and IA to AN-radical to the state in pure DMF. The penultimate model could explain the feed-copolymer composition profile for the whole range. Whereas IA systematically retarded the polymerization rate at all concentration regime in DMF, it increased the rate at higher IA concentration in DMF/TEA system. For a given IA concentration, the polymerization rate decreased as the solvent is enriched in TEA. The copolymers synthesized in the presence of TEA, manifested higher cyclization temperature and consequently lower char residue, attributed to the incorporation of TEA in the polymer by means of salt formation with IA moiety camouflaging the catalytic effect of the -COOH group in cyclization reaction. 13C-NMR studies confirmed the incorporation of the TEA molecules in the polymer chain. 相似文献
946.
Gupta D Roitzsch M Lippert B 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(22):6643-6652
Isocytosine (ICH; 1) exists in solution in an equilibrium of tautomers 1a and 1b with the N1 and N3 positions carrying the acidic proton, respectively. In the solid state, both tautomers coexist in a 1:1 ratio. As we show, the N3H tautomer 1b can selectively be crystallized in the presence of the model nucleobase 1-methylcytosine (1-MeC). The complex 1b x (1-MeC)2 x H2O (2) forms pairs through three hydrogen bonds between the components; hydrogen bonds between identical molecules are also formed, leading to an infinite tape structure. On the other hand, the N1H tautomer 1a co-crystallizes with protonated ICH to give [1a x ICH2]NO3 (3), again with three hydrogen bonds between the partners, yet the acidic proton is disordered over the two entities. With M(II)(dien) (M=Pt, Pd; dien=diethylenetriamine) preferential coordination of tautomer 1a through the N3 position is observed. DFT calculations, which were also extended to Pt(II)(tmeda) linkage isomers (tmeda=N,N,N',N'-tetramethylethylenediamine), suggest that intramolecular hydrogen bonding between the ICH tautomers and the co-ligands at M, while adding to the preference for N3 coordination, is not the major determining factor. Rather it is the inherently stronger Pt-N3 bond which favors complexation of 1a. With an excess of M(II)(dien), dinuclear species [M2(dien)2(IC-N1,N3)]3+ (M=Pd(II), 4 and Pt(II), 5) also form and were isolated as their ClO4(-) salts and structurally characterized. In strongly acidic medium 5 is converted to [Pt(dien)(ICH-N1)]2+ (6), that is, to the Pt(II) complex of tautomer 1b. 相似文献
947.
948.
以4-N,N-二乙基氨基水杨醛为原料,制备了2-(苯并噻唑-2-基)-5-(N,N-二乙基氨基)苯酚衍生物(探针L),并对其结构进行了表征。在DMSO/PBS(体积比3∶7,pH=7.4)溶液中,探针L具有高选择性并可荧光"关-开"识别H_2S,在365nm紫外灯照射下,由无荧光变成蓝色荧光。实验表明,探针L识别H_2S的检测限为2.05×10~(-6)mol/L,pH适用范围为6~9,可用于检测实际水样中的H_2S。 相似文献
949.
V. V. Nikitenko A. I. Martynenko S. A. Ostrovsky V. V. Rusak V. V. Kryuchkov D. A. Topchiev 《Russian Chemical Bulletin》1993,42(2):378-380
3-Methyl-l-vinylpyrazole (M3VP) and 5-methyl-1-vinylpyrazole (M5VP) were isolated as individual substances by vacuum rectification of their mixture (M3VP: M5VP 60 40). For each of them the kinetics of free-radical polymerization in MeOH were measured at low conversions. In both cases the rate of polymerization is proportional to 0.5 order with respect to the initiator (AIBN) concentration. On the other hand, a first order of reaction with respect to monomer concentration is observed only when the latter is relatively low (3M). At higher initial concentrations of monomers the order of reaction becomes less than unity. The overall rate of polymerization for M5VP was higher than for M3VP, whereas the initiation rate remained constant in the whole range of monomer concentrations and did not depend on the exact structure of the monomer. The difference in the rates of polymerization observed for M3VP and M5VP is probably connected with the difference in the key parameterk
p/k
t
1/2
for each of the two isomers. It is concluded that the correct kinetic information about homo- and co-polymerization of M3VP and M5VP cannot be obtained without their adequate separation.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 413–415, February, 1993. 相似文献
950.
用停止-流动分光光度法研究了Eu~(2+)与二甲酚橙(XO)间快速电子转移反应的动力学规律。求得了速控步骤的动力学参数。如反应级数(n=2)、几个不同温度下的速率常数(k_(278 K)=5.7×10~8 L·mol~-·s~(-1), k_(s38 K)=1.01×10~9 L·mol~(-1)·s~(-1))、活化能(E=7.6×10~3 J·mol~(-1)), 以及指前因子(A=1.5×10~(10) L·mol~(-1)·s~(-1)), 并判断出其为溶液中扩散控制型反应。根据实验现象与测试结果, 提出了Eu~(2+)与XO的反应分别在Eu~(2+)相对过量和在XO过量时的反应机理, 并判断了各反应步骤速率常数之间的相对关系。 相似文献