动力学体系二维数据的秩分析及其应用

详细论证了动力学体系中存在的多种共线性情况,以及在此情况下二维数据阵的秩与独立反应数及组分数的关系.分析了通过增秩这一方式来判断体系组分数的条件.讨论了反应间存在物质交换对数据阵秩的影响.建立起一套通过秩分析判断未知动力学体系中存在的反应组分数、独立反应数以及可能反应机理的方法.将秩分析技术应用到聚苯胺与质子酸反应,初步分析了该体系存在的多种吸光性结构及结构变化.确定了[H＋]=0.01～0.1 mol•L－1范围内,聚苯胺与质子酸反应存在一个三结构两步互变过程.     

Preparation and reactivity of metal-containing monomers

Mono- and disubstituted cluster metal-containing monomers were obtained under mild conditions on interaction of Rh₆(CO)₁₆ with 4-vinylpyridine (4-ViPy) in the presence of N-trimethylaminoxide. These products were characterized by IR and¹H NMR spectroscopy and by elemental and X-ray analyses. Rh₆(CO)₁₅(4-ViPy) was found to be an octahedral cluster with eleven terminal and four ₃-bridging carbonyl ligands. 4-ViPy is linked with the Rh(3) atom through the N atom and occupies the coordination site of the twelfth CO terminal ligand. The mean value of the Rh-Rh bond length is 2.762 Å. The unsaturated ligand has little or no effect on the geometry of the starting cluster and its double bond retains the ability to undergo addition reactions.For part 28, seeRuss. Chem. Bull., 1993, 453.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 975–979, May, 1993.     

Erosion of efficiency in non-uniform linear chromatography

In linear chromatography (i.e. chromatography performed in the absence of sample overloading), when the plate height of a column is roughly uniform along its length, variations in the velocities of solutes are the only possible causes of erosion of efficiency. The sources of these variations (variations in capacity ratio and in the density of the mobile phase, etc.) play no direct role in the erosion of efficiency except through their effect on solute velocities. In other words, what eventually causes the erosion of efficiency is merely variation in the time required for solutes to traverse equally small segments of a column. Significant erosion can only arise from abrupt and deep deceleration of solutes in one or several relatively small segments of a column. If erosion of efficiency caused by pressure gradients in linear SFC is to be large, the depth and the sharpness of the deceleration of a solute must go beyond that hitherto confirmed experimentally. Many relevant examples are analyzed graphically.     

Strukturelle Abwandlungen anN-Acetylneuraminsäure, 3

From methyl-5-acetylamino-7,8-anhydro-4,9-O-bis-(t-butyldimethylsilyl)-3,5-dideoxy--D-glycero-D-galacto-2-nonulopyranosidonic acid methylester (1) the derivatives1 a and1 b were obtained by removing the 9-O-(t-butyldimethylsilyl)group withBu ₄NF, followed by acetylation. Treatment of1 b with 80% acetic acid and acetanhydride/pyridine yields the 8-epi-N-acetylneuraminic acid derivative2 a and the 7-epi-N-acetylneuraminic acid derivative3 a in a ratio of 3:1 (Scheme 1). The structure elucidation of2 b was achieved by converting2 b via the 4,9-bis-O-(tBDMSi)-8-O-tosyl-derivative2 d into the epoxide1 (Scheme 2). Using the same sequence the epoxides4 and5 were transformed into theN-acetylneuraminic acid derivative6 a and the 7,8-bis-epi-N-acetylneuraminic acid derivative7 a (Scheme 3). After treatment with sodium hydroxide and 0.025m HCl and Dowex 50 H⁺ the 8-epi-, 7-epi- and 7,8-bis-epi-N-acetylneuraminic acids2,3, and7 were obtained. These three compounds were tested withCMP-N-acetylneuraminic acid synthetase.

Herrn KollegenK. Schlögl mit den besten Wünschen zum 60. Geburtstag.     

Applications of a miniaturized fluorimetric photodiode array detector for capillary liquid chromatography

A high sensitivity, multichannel fluorescence detector with small volume has been developed for capillary column liquid chromatography. Using an intensified linear photodiode array to monitor fluorescence emission, several important mixtures exhibiting native fluorescence have been examined following high efficiency separation on a capillary column. By correlating mass spectral, fluorescence spectral, and retention time data, information of potential utility in the structural elucidation of aromatic molecules contained in complex mixtures can be obtained. Examples include the separation and spectral examination of the polyaromatic compounds in samples of both biological and environmental interest.     

Conductance studies in amide-water mixtures. II. Sodium salts inN,N-dimethylformamide-water mixtures at 35°C

Conductance data for sodium nitrite, chloride, and acetate in water andN,N-dimethylformamide (DMF)-water mixtures (74.82D42.48) for the concentration range 0.001–0.04N, as well as the densities, viscosities, and dielectric constants of the solvent mixtures at 35°C, are reported. The data have been analyzed by the Fuoss (1975) equation. The existence of a maximum in the viscosity at a 13 mole ratio of DMF and water is indicated. The Walden products for all the three salts pass through a maximum while the equivalent conductances show a minimum with increasing DMF content. The maxima in the Walden product are attributed to the dehydration of ions by the cosolvent (DMF).Part I:Indian J. Chem. 14A, 1015 (1976).Deceased.     

除草剂2-甲基-4-氯苯氧乙酸(MCPA)与OH自由基的气相化学反应

采用长光程气体池结合傅里叶变换红外光谱仪测得了除草剂2-甲基|4|氯苯氧乙酸(MCPA)与·OH自由基在23 ℃时的反应速率常数为2.67×10-11  cm3/(s*mol), 以此估算了在大气中·OH自由基浓度为 7×105  mol/cm3时, MCPA与·OH自由基反应导致的大气寿命为14.9 h. 结果表明, 在大气环境中MCPA较容易降解, 不会通过大气输送对环境造成广泛和持久性污染.      

Classification of oxide glasses: A polarizability approach

A classification of binary oxide glasses has been proposed taking into account the values obtained on their refractive index-based oxide ion polarizability α_O2−(n₀), optical basicity Λ(n₀), metallization criterion M(n₀), interaction parameter A(n₀), and ion's effective charges as well as O1s and metal binding energies determined by XPS. Four groups of oxide glasses have been established: glasses formed by two glass-forming acidic oxides; glasses formed by glass-forming acidic oxide and modifier's basic oxide; glasses formed by glass-forming acidic and conditional glass-forming basic oxide; glasses formed by two basic oxides. The role of electronic ion polarizability in chemical bonding of oxide glasses has been also estimated. Good agreement has been found with the previous results concerning classification of simple oxides. The results obtained probably provide good basis for prediction of type of bonding in oxide glasses on the basis of refractive index as well as for prediction of new nonlinear optical materials.     

流体熵相关性质的Monte Carlo模拟新方法

提出了用于计算实际体系熵相关性质的Monte Carlo多级取样分子模拟方法. 应用这一方法, 对硬球流体的化学势及Helmholtz自由能进行了估算, 得到了满意的结果. 计算化学势时, 不存在通常试验粒子方法所遇到的高密度问题. 该方法特别适合规律性的系统研究, 较之普通模拟方法要有效得多. 模拟得到的硬球体系无限稀释组份的超额化学势与对比直径的关系, 在相变区域为一条双凹曲线; 无论是在相变区还是在单相区, Carnahan-Starling公式对这一关系的描述均有较大偏差.     

邻苯二甲酸在异丙醇-水混合溶剂中电离热力学性质的研究

The first thermodynamic dissociation constants of o-phthalic acid were determined at five temperatures from 278.15 to 318.15 K in 10, 14.93 and 20 wt% isopropanol-water solvent mixtures, by precise e. m. f. measurements of hydrogen-silver chlorld electrodes in cells without liquid junction. On the basis of Pitzer's theory, the method of polynomial approximation was used to determine the dissociation constants of H_2P and the results obtained were compared with traditional extrapolation according to the extended Debye-Huckel equation Results obtained from both methods agree within experimental error. The dependence of the first thermodynamic dissociation constant on temperature was given as a function of the thermodynamic temperature T by the empirical equation: pK_1=A_0+A_1/T+A_2/T. The thermodynamic quantities of dissociation in the mixed solvents have been calculated, and the results have been discussed.