苯胺气相N－烷基化反应研究Ⅱ．苯胺和乙醇常压催化合成N－乙基苯胺的工业应用

苯胺气相Ｎ－烷基化反应研究Ⅱ．苯胺和乙醇常压催化合成Ｎ－乙基苯胺的工业应用陈骏如，李瑞祥，韩银仙，李贤均（四川大学化学系成都６１００６４）Ｎ－乙基苯胺是制造染料、塑料、炸药和医药等许多化工产品的重要中间体，其合成方法过去多采用无机酸催化剂，如Ｈ＿２Ｓ...     

Interaction between 18-crown-6-tetracarboxylic acid and positional substituents of enantiomers and simultaneous separation of positional enantiomers of methyl-DL-tryptophans by capillary electrophoresis

18-Crown-6-tetracarboxylic acid (18C6H4) is a chiral selector with high selectivity for the enantioseparation of solutes bearing the primary amine function. This work presents the simultaneous separation of positional enantiomers of methyl-DL-tryptophans by using 18C6H4 as an additive to the background electrolyte. Separation conditions such as pH, the concentration of 18C6H4, and the applied voltages have critical inference on the simultaneous separation. The addition of cyclodextrins as anionic surfactants to the background electrolyte did not improve the separation. The selector-selectand interactions between 18C6H4 and the positional enantiomers have been investigated. It was observed that both the position and type of substituents contribute to the enantioselectivity. The migration order and resolution depended on the distance from the substituents to the asymmetric carbon of the enantiomers.     

Chiral separation of N-(trans-4-isopropylcyclohexylcarbonyl)-D,L-phenylalanine isomers by high performance liquid chromatography

Summary A high-performance liquid chromatographic method was developed for the chiral separation of a new anti-diabetic agent, N-(trans-4-isopropylcyclohexylcarbonyl)-D-phenylalanine, and its L-enantiomer. The separation was performed on a Sumichiral OA-3300 column. Optimized mobile phase was 0.025 mol.L⁻¹ ammonium acetate in methanol solution. UV detection was at 210 nm. Baseline chiral separation was obtained within 12 minutes. The detection limits are 80 pg for the D-enantiomer and 120 pg for the L-enantiomer. RSD of the method was below 1% (n=5).     

Chemical Vapor Deposition of Silicon Dioxide by Direct-Current Corona Discharges in Dry Air Containing Octamethylcyclotetrasiloxane Vapor: Measurement of the Deposition Rate

Experiments in a positive-polarity, wire/plate electrode establish the effects of the concentration of octamethylcyclotetrasiloxane (150–1100 ppm) and the operating current (0.5–2.55 μA/cm length of wire) on the rate of deposition of silicon dioxide on the high voltage wire. The wire is 100 μm radius tungsten and the wire-to-plate spacing is 1.5 cm. Analyses of the deposit with X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy show that it is amorphous silicon dioxide. The deposition rate increases linearly with increasing silicone concentration and corona current. For the concentrations of silicone likely to present in indoor air, the gas-phase processes limit the rate of deposition.     

Dichloro bis(η5) molybdenum catalysed reduction of organic halides by sodium borohydride

Summary Dichloro bis(⁵) molybdenum catalyses the reduction of organic halides by sodium borohydride smoothly and selectively. The reactions with representative organic monohalides and polyhalides are investigated. The ease of reduction depends on the structure of the halide and the solvent used. alkoxycarbonyl and cyano groups are unattacked in the reaction. An oxidative addition-reductive elimination mechanism is tentatively suggested.     

Acidities in cyclohexanediols enhanced by intramolecular hydrogen bonds

Equilibrium gas-phase acidities of the six isomeric cyclohexanediols were measured in a Fourier transform ion cyclotron resonance mass spectrometer. Although all six cyclohexanediols have the same functional groups and similar structures, the acidities vary over 11 kcal/mol. This large difference is due mostly to the balance between hydrogen bonding and geometric strain. To understand the origins of the acidity differences in more detail, the conformations and energetics of the cyclohexanediols were studied using density functional theory, which gave good agreement with the experimental acidities. Finally, methanol-methoxide and methanol-methanol interactions were used as a model for the hydrogen bonding.     

Aggregate manganese Schiff base moieties by terephthalate or acetate: dinuclear manganese and trinuclear mixed metal Mn2/Na complexes

A reaction system consisting of terephthalic acid, NaOH, inorganic Mn(II) or Mn(III) salt, and salicylidene alkylimine resulted in dinuclear manganese complexes (salpn)(2)Mn(2)(mu-phth)(CH(3)OH)(2) (1, salpn = N,N'-1,3-propylene-bis(salicylideneiminato); phth = terephthalate dianion), (salen)(2)Mn(2)(mu-phth)(CH(3)OH)(2) (2, salen = N,N'-ethylene-bis(salicylideneiminato)), (salen)(2)Mn(2)(mu-phth)(CH(3)OH)(H(2)O) (3), and (salen)(2)Mn(2)(mu-phth) (4), while the absence of NaOH in the reaction led to a mononuclear Mn complex (salph)Mn(CH(3)OH)(NO(3)) (5, salph = N,N'-1,2-phenylene-bis(salicylideneiminato)). In addition, a trinuclear mixed metal complex H[Mn(2)Na(salpn)(2)(mu-OAc)(2)(H(2)O)(2)](OAc)(2) (6) was obtained from the reaction system by using maleic acid instead of terephthalic acid. Five-coordinate Mn ions were found in 4 giving rise to an intermolecular interaction and constructing a one-dimensional linear structure. Antiferromagnetic exchange interactions were observed for 1-3, and a total ferromagnetic exchange of 4 was considered to stem from intermolecular magnetic coupling. (1)H NMR signals of phenolate ring and alkylene (or phenylene) backbone of the diamine are similar to those reported in the literature, and the phth protons are at -2.3 to -10.1 ppm. Studies on structure, bond valence sum analysis, and magnetic properties indicate the oxidation states of the Mn ions in 6 to be +3, which are also indicated by ESR spectra in dual mode. Ferromagnetic exchange interaction between the Mn(III) sites was observed with J = 1.74 cm(-1). A quasireversible redox pair at -0.29V/-0.12V has been assigned to the redox of Mn(2)(III)/Mn(III)Mn(II), implying the intactness of the complex backbone in solution.     

一组新的高分子溶液粘度与浓度关系函数式

<正> 粘度法是测定高聚物分子的大小与结构最简便、最常用的方法.在用粘度法测定高聚物分子大小与结构时,需求得极限粘数[η].为此,需确立高分子溶液粘度与浓度的关系,文献中有过种种不同的函数式.通常,将ηsp/c、logηsp/c、lnηr/c对c或ηsp/c对ηsp作图外推到c为零或ηsp为零得[η].Heller对各种外推方法进行了详细的研究,可是到目前为止,采用的成对外推公式不多,且有明显的缺陷.