A Chiral Coordination Polymer of Silver(I) with Saccharinate and Pyridine: Synthesis,Spectral, Thermal,and Structural Characterization of [Ag(sac)(py)]<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>

The first silver(I) complex of saccharinate (sac) with pyridine (py), [Ag(sac)(py)]_n has been synthesized and characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffractometry. The complex crystallizes in chiral, trigonal space group P3₁21 (No. 152) with unit cell parameters of a = 11.2605(2) Å, c = 17.3300(4) Å, V = 1903.02(6) ų and Z = 6. [Ag(sac)(py)]_n contains monomeric [Ag(sac)(py)] units linked into infinite helices by way of Ag⋅sAg interactions [d(Ag⋅sAg) = 2.909(2) and 2.985(1) Å]. The distorted square-planar environment of Ag is completed by an N-bonded sac [Ag—N = 2.084(2) Å] and a py molecule [Ag—N = 2.116(2) Å]. The N_sac—Ag—N_py angle is 173.85(10)^∘. The one-dimensional chains are crosslinked by C—H⋅sO interactions involving the carbonyl and sulfonyl O atoms of sac and aromatic-ring hydrogen atoms of both sac and py. The thermal stability of the title complex was investigated using thermogravimetry and differential thermal analysis in a static atmosphere of air. The first decomposition stage between 90 and 160^∘C corresponds to removal of the py molecule in a single stage, while the degradation of the sac moiety occurs at two stages in the temperature range 370–515^∘C, giving an end product of metallic Ag.     

Synthesis of Functionalized (2-Thienylcarbonyl)thiazoles and 4-(2-Thienyl)pyridines by Reaction of (2-Thienylcarbonyl)thioacetanilides and their Enamine Derivatives

Summary. The condensation of two molecules of 2-(2-thienylcarbonyl)thioacetanilides catalyzed by piperidine yielded thiazole derivatives as confirmed by X-ray crystal structure analysis. The reaction of malononitrile with 3-morpholino-3-(2-thienyl)acrylic acid thioanilides furnished 6-amino-1-aryl-4-(2-thienyl)-1,2-dihydro-2-thioxopyridine-5-carbonitriles. A similar reaction of malononitrile with 3-morpholino-3-(2-thienyl)acrylic acid anilides provided 2-oxopyridine-5-carbonitriles.     

2-取代吡啶半菁染料的无溶剂微波合成及光谱性质的理论研究

在微波促进无溶剂条件下, 由N-甲基-2-甲基吡啶碘盐与取代芳香醛在哌啶作用下合成了一系列2-取代的吡啶半菁染料, 产物结构由元素分析, ¹H NMR, MS, IR, UV得到确认. 该方法操作简便, 收率高. 在此基础上, 对N-甲 基-2-(p-N,N-二甲氨基-苯乙烯基)吡啶半菁染料的光谱性质进行了理论计算.     

含二茂铁和吡啶单元的手性席夫碱配体在钌催化的不对称氢转移反应中的应用

Chiral Schiff base complexes are very efficient for a wide range of reactions, including expoxidation[1], epoxide ring opening[2], Diels-Alder reaction[3], aldol reaction[4], etc. However, there are only few examples of P-N chelate Schiff bases being used as the chiral ligands in the asymmetric transfer hydrogenation of ketones. Recently, Gao et al[5] reported a series of P,N,N,P Schiff base ligands that have relatively low enantioselectivity in the asymmetric transfer hydrogenation of ketones.     

镓改性ZSM-5沸石中镓活性中心的形成与表征

采用脉冲微反体系研究了经不同程度还原和不同镓含量的GaZSM-5沸石的芳构化性能与吡啶吸附红外光谱特征谱带吸收度的关联，证实了1458 cm~(-1)吸收带的用于表征与Ga物种有关的活性中心，并研究了沸石的硅铝比对Ga中心形成和Ga的价态对芳构化性能的影响。结果表明，对Ga含量相同的样品来说，硅铝比愈低，起始Ga中心生成量愈多，高价态与低价态的Ga中心对丙烷芳构化反应都有促进作用。     

An automated FTIR method for the routine quantitative determination of moisture in lubricants: An alternative to Karl Fischer titration

An accurate primary Fourier transform infrared (FTIR) method for the determination of moisture in mineral and ester based lubricants has been developed based on the extraction of moisture into dry acetonitrile. FTIR evaluation of acetonitrile extracts from new and used lubricants as well as common lubricant additives and contaminants which might co-extract indicated that phenolic constituents interfered significantly with moisture measurements. By measuring moisture at 3676 cm⁻¹ on the shoulder of the asymmetric OH stretching band, spectral interferences from extracted phenolic constituents were minimized. The spectra of calibration standards (0-2100 ppm), prepared by gravimetric addition of water to dry acetonitrile, were recorded in a 1000-μm CaF₂ transmission flow cell and produced linear standard curves having an S.D. of ∼±20 ppm. Lubricant sample preparation involved the vigorous shaking (20 min) of a 1:1.5 (w/v) mixture of lubricant and dry acetonitrile, centrifugation to separate the phases, acquisition of the FTIR spectrum of the upper acetonitrile layer, and subtraction of the spectrum of the dry acetonitrile used for extraction. A Continuous Oil Analyzer and Treatment (COAT^®) FTIR system was programmed to allow the automated analysis of acetonitrile extracts, and the methodology was validated by analyzing 58 new and used oils, independently analyzed by the Karl Fischer (KF) method. Linear regression of FTIR versus KF results for these oils produced a linear plot with a between-method S.D. of ±80 ppm. As implemented on the COAT^® system, this FTIR method is capable of analyzing 72 acetonitrile extracts/h and provides a high-speed alternative to the KF titrimetric procedures for the determination of water in lubricants.     

Synthesis of o-carborane-C-carboxylates of certain natural terpene alcohols, sterols, phenols, and camphar oxime

Previously unreported esters 1b–20b were synthesized from natural terpene alcohols, sterols, plant phenols, and camphar oxime (1a–20a) by reaction with o-carborane-C-carboxylic acid chloride. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 434–436, September–October, 2006.     

Recovery of pyridine from aqueous solution by membrane pervaporation

Three different membranes, based on poly(dimethylsiloxane) (PDMS), cation-exchange material and poly(vinyl alcohol) (PVA) respectively, were tudied for the separation of pyridine-water mixtures by pervaporation. The PDMS membrane was preferentially permeable to pyridine and the other two were selective towards water. Three membranes showed different permeation performance, allowing the application of the technique to the separation of feeds of different composition. The temperature profile of the permeability suggests that it is possible to carry out the operation at an elevated temperature in order to achieve high productivity. A combination of the three types of membranes was designed for the production of anhydrous pyridine from dilute pyridine aqueous solution by pervaporation.     

Flammability studies of 3-methyl pyridine/water system

In industrial processes, information on the safety property of chemicals is essentially crucial for safe handling during unit operations. Ensuring the safe use of combustible or flammable substances in processes is unlikely without detailed investigations of their flammability characteristics and related hazards. We studied 3-methyl pyridine (3-picoline), e.g., flammability limits (LFL/UFL), maximum explosion pressure (P _max), maximum explosion pressure rise (dP/dt)_max, minimum oxygen concentration (MOC), vapor deflagration index (K _g), and characterized the influence of inert steam (H₂O) on critical parameters for 3-picoline/water mixtures at 270°C, 1 atm, various oxygen concentrations, and vapor mixing ratios (100/0, 30/70, 10/90 and 5/95 vol.%) with a 20-L-Apparatus in simulated conditions, respectively. The results showed that the flammability characteristics of 3-picoline_(aq) all increased with the oxygen concentration. However, as the composition of inert steam increased, the flammability parameters and the degree of fire and explosion hazards were significantly reduced, instead. This study elucidated the flammability properties of 3-picoline mixed with inert steam. The conclusions could be applied to proactively prevent the relevant processes from incurring fire and explosion accidents.