2-(2-Hydroxyaryl)cinnamic amides: a new class of axially chiral molecules

The syntheses of several differently substituted amides formally derived from a chiral amine, either E-2-(2-hydroxyphenyl)cinnamic acid or both E- and Z-2-(2-hydroxynaphthyl)cinnamic acid, are reported. These molecules display a restricted rotation about the C₂-C_aryl bond. The barriers to rotation about the C₂-C_aryl bond were measured by the dynamic ¹H NMR and were found to vary between 11.8 and 24.5 kcal mol⁻¹, depending on the substitution. In particular, E-2-(2-hydroxynapthyl)cinnamic amides, displayed a high barrier to rotation (ΔG_c^‡=24.4 kcal mol⁻¹) and could be isolated in both diastereomerically pure forms at room temperature. The X-ray structure of one E-2-(2-hydroxynapthyl)cinnamic amide, was resolved, enabling for the determination of the absolute configuration of the chiral axis (aR).     

Determination of Ascorbic Acid Using a New Oscillating chemical System of Lactic Acid—Acetone—BrO3^— —Mn^2 —H2SO4

ＩｎｔｒｏｄｕｃｔｉｏｎＯｓｃｉｌｌａｔｉｎｇｒｅａｃｔｉｏｎｓａｒｅｃｏｍｐｌｅｘｄｙｎａｍｉｃｓｙｓｔｅｍｓｔｈａｔｉｎｖｏｌｖｅｐｅｒｉｏｄｉｃｃｈａｎｇｅｓｉｎｔｈｅｃｏｎｃｅｎｔｒａｔｉｏｎｏｆｓｏｍｅｉｎｇｒｅｄｉｅｎｔｓ (ｗｈｅｔｈｅｒａｒｅａｃｔａｎｔ,ａｐｒｏｄｕｃｔｏｒａｎｉｎｔｅｒｍｅ ｄｉａｔｅ)ｗｉｔｈｔｉｍｅ .Ｔｈｅｓｉｍｉｌａｒｉｔｉｅｓｂｅｔｗｅｅｎｌｉｆｅｐｒｏｃｅｓｓｅｓｔｈａｔｅｘｈｉｂｉｔｏｓｃｉｌｌａｔｉｎｇｂｅｈａｖｉｏｒａｎｄｏｓｃｉｌｌａｔｉｎｇｃｈ…     

Determination of Ascorbic Acid in the Presence of Uric Acid and Folic Acid by a Nanostructured Electrochemical Sensor Based on a TiO2 Nanoparticle Carbon Paste Electrode

A carbon paste electrode (CPE), modified with novel hydroquinone/TiO₂ nanoparticles, was designed and used for simultaneous determination of ascorbic acid (AA), uric acid (UA) and folic acid (FA). The magnitude of the peak current for modified TiO₂-nanoparticle CPE (MTNCPE) increased sharply in the presence of ascorbic acid and was proportional to its concentration. A dynamic range of 1.0–1400.0 μM, with the detection limit of 6.4 × 10^?7 M for AA, was obtained using the DPV technique (pH = 7.0). The prepared electrode was successfully applied for the determination of AA, UA, and FA in real samples.     

Selenious Acid as a Ligand: Molecular and Crystal Structure of [Co(H2O)2Cl2(H2SeO3)2]

[Co(H₂O)₂Cl₂(H₂SeO₃)₂] (monoclinic, P2₁/c, Z = 2, a = 519.82(5), b = 1462.6(1), c = 643.09(7) pm, β = 92.51(1)°, R_all = 0.0583) was obtained from CoCl₂ and H₂SeO₃ as purple plate–shaped single crystals. In the compound, the Co²⁺ ions are octahedrally coordinated by two Cl^? ions, two H₂O molecules, and two monodentate H₂SeO₃ molecules, leading to neutral complexes [Co(H₂O)₂Cl₂(H₂SeO₃)₂]. They are connected by hydrogen bonds involving both chlorine and oxygen atoms as acceptor atoms.     

Synthesis and study of (2S,4S)-4-arylamino-2-carboxy-5-pyrrolidones

(2S,4S)-4-Arylamino-2-carboxy-5-pyrrolidones were prepared by hydrolysis of dimethyl (2S,4S)-4-arylamino-N-phthaloylglutamates. The protonation constants of the arylamino group in the synthesized compounds were determined. The pyrrolidone ring is stable in acidic or neutral solutions. The relative stability of the pyrrolidone ring in alkaline solutions was studied by IR spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2087–2090, December, 1993.     

Novel and Efficient Synthesis of tert-Butyl-2-(4-(2-aminoethyl)phenylthio)-2-methylpropanoate,a Key Intermediate in the Synthesis of Ureido Thioisobutyric Acid

A convenient and cost-effective synthesis of pharmacologically important tert-butyl-2-(4-2-aminoethyl)phenylthio)-2-methylpropanoate from commercially available 2-2-phenyl-1-ethanol is described.     

Synthesis and Crystal Structure of a 2-D Framework Supramolecular Complex [Cd2（phen）2（adip）（NO3）2]

1 INTRODUCTION In the design of crystal molecule, inorganic crystal engineering is one of the focused fields that are ever developing[1]. The introduction of different metal ions and bridging ligands often gives rise to novel physical and chemical properties[2~4]. Conse- quently, the supramolecular compounds constructed from weak interactions, such as hydrogen bond, π-π stacking, C–H???O interaction, ion-π interaction and hy- drophobing interaction, have become the new focus of cryst…     

新显色剂2-[2-噻唑偶氮]-5-二乙氨基苯甲酸与铑显色反应的研究

本文合成了新显色剂2-[2-噻唑偶氮]-5-二乙氨基苯甲酸(TAEB),研究了它与铑的显色反应。结果发现,在pH4.0～6.5的缓冲溶液中,铑(Ⅱ)与TAEB形成一种绿色络合物。其最大吸收波长为674nm,表现摩尔吸光系数为1.44×10~5L·mol~(-1)cm~(-1)。铑含量在0～20μg/25ml范围内服从比尔定律。络合物中铑(Ⅱ)与TAEB的摩尔比为1:1。该方法灵敏度高、选择性好。常见的阴、阳离子不干扰,镍(Ⅰ)、钴(Ⅰ)和铜(Ⅰ)的干扰可用EDTA来消除,用于催化剂中微量铑的测定。结果令人满意。     

Structure and magnetism of a new 2-D trinuclear Mn(II) polymer

A new complex, {[Mn₃(oba)₂(IP)₂(CH₃COO)₂]·H₂O}_n (1) (H₂oba?=?4,4′-oxybis(benzoic acid), IP?=?1-H-imidazo[4,5-f][1,10]-phenanthroline), has been synthesized and structurally characterized by single-crystal diffraction analysis. The structural determination revealed that 1 has a 2-D grid motif, which can be further linked into a 3-D porous network via packing interactions. The magnetic properties of 1 are discussed.     

Microwave-assisted synthesis of 2-aminonicotinic acids by reacting 2-chloronicotinic acid with amines

2-(Methylamino)nicotinic acid was readily prepared in high yield by reacting 2-chloronicotinic acid with 40% aq MeNH₂ under microwave irradiation either at 120 °C for 2 h or at 140 °C for 1.5 h. Subsequently, we found that a range of 2-aminonicotinic acids could be obtained under microwave heating. The optimal reaction conditions involved the use of 3 equiv of amine, water as the solvent and heating at 200 °C for 2 h in the presence of diisopropylethylamine (3 equiv).     

Synthesis and Structural Characterization of a Novel 2D Supramolecular Complex {[Dy_2Zn(dinic)_4(H_2O)_8]·H_2O}n (H_2dinic = 2,5-Pyridinedicaboxylic Acid)

1INTRODUCTION Studies on the syntheses,structures,and proper-ties of lanthanide-transition metal complexes are currently of great interest not only due to their beha-viors as good models to investigate the nature of magnetic exchange interactions between3d and4f metal ions in magnetic materials but also to the fascinating coordination properties of Ln(III)[1～6].Although some infinite lanthanide(III)-transition metal compounds have been obtained by the con-ventional self-assembly reacti…     

α-(2-噻唑基脲基)膦酸二苯酯的合成

报道了一种简便的合成取代脲基膦酸酯的通用的新方法。在二氯甲烷中,三乙胺为缚酸剂的条件下,α-氨基膦酸二苯酯与三聚光气反应形成α-异氰酸基膦酸酯2,2不经分离,直接与2-氨基(苯并)噻唑加成得到α-(2-噻唑基脲基)膦酸二苯酯3,产率55.0%-88.9%。     

Dimethylphosphinato and Dimethylarsinato Complexes of Palladium(II), [Pd(Me2PO2)2]3 and Pd(Me2AsO2)2, and their Adducts

The complexes [Pd(Me₂PO₂)₂]₃ and Pd(Me₂AsO₂)₂ were prepared from the corresponding acids and palladium(II) acetate. Their structures were deduced by IR and NMR spectroscopy. Addition of pyridine and 2,2′‐bipyridine to [Pd(Me₂PO₂)₂]₃ gave the adducts Pd(Me₂PO₂)₂py₂ and Pd(Me₂PO₂)₂bipy, which were characterized by ¹H NMR spectroscopy. Addition of nicotinic acid and nicotinamide in water gave the adducts Pd(Me₂PO₂)₂L₂, whereas in methanol the adducts Pd(Me₂PO₂)₂L were obtained. The cacodylate containing complex formed the adducts Pd(Me₂AsO₂)₂py and Pd(Me₂AsO₂)₂bipy_1/2, which are unstable in CDCl₃. Triphenylphosphine deoxygenated both Pd(Me₂MO₂)₂ complexes, but the palladium(II) containing products could not be isolated. The expected Pd(Me₂P–O)₂ reacted further and gave many products, whereas the anticipated Pd(Me₂As–O)₂ did not bind triphenylphosphine.     

α-H_6P_2W_(18)O_(62)·37H_2O的热稳定性

通过溶解性实验、变温红外、紫外光谱、X射线粉末衍射(XRD)和热重-差热分析(TG DTA)等手段,对Dawson结构钨磷酸的热稳定性进行了较系统的研究,结果表明,阴离子骨架在360℃左右开始分解,并提出了化合物热分解的可能机理.     

Direct Synthesis of Acetic Acid from CH4 and CO2 in the Presence of O2 over a V2O5-PdCl2／Al2O3 Catalyst

The possibility of synthesizing acetic acid from CH4 and CO2 in the presence of O2 over a V2O5-PdCl2/Al2O3 catalyst has been explored. The result shows that it is feasible in catalyzing a direct conversion of CH4, CO2 and O2 to acetic acid. It is concluded that both CO2 and O2 are involved in the formation of acetic acid.     

Synthesis and Crystal Structure of a Novel Zinc Complex [Zn(OH_2)(HDPA)_2]·3H_2O

1INTRODUCTION In recent years,dicarboxylic acids have been wide-ly used as poly-dentate ligands involved in various metal chelation reactions to form transition or rare earth metal complexes with interesting properties in material science[1~3]and biological systems[4~7].For example,Kim,Y.and his coworkers focus on the syn-theses of copper(II)complexes containing ligands of malonate and pyrazine to study their electronic con-ductivity and magnetic property[8].The importance of Tr(II)/dic…     

The peculiar reaction of 2-arylazo-1-vinylpyrroles with trifluoroacetic acid: a novel synthesis of 2-methylquinolines

2-Arylazo-1-vinylpyrroles 1-6 react with CF₃CO₂H (benzene, reflux, 5 h) in a peculiar way: instead of expected electrophilic addition of CF₃CO₂H to the N-vinyl group, the latter is transferred to the azo group followed by NN bond cleavage to afford substituted 2-methylquinolines 10-12 in up to 56% yields. The reaction was shown (¹H, ¹³C, and ¹⁵N NMR) to start with the protonation of the azo group with further inter- and intramolecular involving of two protonated N-vinyl groups to finally build up the quinoline cycle over the aryl moiety.     

双核有机锡(Ⅳ)配合物[Ph_3Sn(CH_3OH)O_2CC_6H_4CO_2(CH_3OH)-SnPh_3]·2CH_3OH和[Ph_3SnS_2CN(CH_2CH_2)_2NCS_2SnPh_3]·2CH_3OH的合成、表征和晶体结构

利用三苯基氯化锡和对苯二甲酸二钠、哌嗪荒酸二钠在甲醇中反应 ,合成了双核有机锡 (Ⅳ )配合物 [Ph3 Sn (CH3 OH)O2 CC6H4 CO2 (CH3 OH)SnPh3 ]·2CH3 OH (1)和 [Ph3 SnS2 CN(CH2 CH2 ) 2 NCS2 SnPh3 ]·2CH3 OH (2 ) .通过元素分析、红外光谱和核磁共振氢谱对其结构进行了表征 .用X射线单晶衍射测定了这两个化合物的晶体结构 .化合物 1为单斜晶系 ,空间群P2 1/n ,a =1.5 199(5 )nm ,b =0 .90 0 0 (3)nm ,c =1.82 0 6 (6 )nm ,β =113.970 (5 )° ,Z =2 ,V =2 .2 75 5(13)nm3 ,Dc=1.413g/cm3 ,μ =1.146mm-1,F(0 0 0 ) =980 ,R1=0 .0 35 3,wR2 =0 .0 6 0 6 .化合物 2为单斜晶系 ,空间群P2 1/c,a =1.5 0 6 6 (5 )nm ,b =1.0 875 (4 )nm ,c =1.35 42 (5 )nm ,β =91.6 14(5 )°,Z =2 ,V =2 .2 178(14)nm3 ,Dc=1.498g/cm3 ,μ =1.35 1mm-1,F(0 0 0 ) =10 0 8,R1=0 .0 40 1,wR2 =0 .1148.在 1和 2的晶体中 ,锡原子呈五配位畸变三角双锥构型 .配合物 1由未配位的甲醇分子通过氢键作用形成二维网状结构     

固体酸催化剂SO2-4/SiO2-TiO2的制备及其催化酯化性能

 分别以机械混合法和浸渍法制备了SO2-4/SiO2-TiO2固体酸催化剂,以乙醇和乙酸的酯化反应为模型反应考察了不同SiO2含量及不同温度焙烧的催化剂的活性. 结果表明,机械混合法制备的400 ℃焙烧的SO2-4/40%SiO2-TiO2催化剂活性最高,部分回流时,乙酸几乎全部转化,全回流反应100 min时,其乙酸转化率达到84%. X射线衍射分析表明, SiO2抑制了硫酸氧钛的形成; 催化剂的活性组分包括一定量的四方晶锐钛矿型TiO2、 正交晶硫酸氧钛、少量立方晶金属钛和高比表面积的SiO2. 红外光谱分析表明,添加SiO2后催化剂形成 Ti-O-Si 键,进而使SO2-4与样品表面产生强相互作用; 结合的SO2-4主要以无机螯合状双配位和有机硫酸酯两种结构形式存在. 热重-示差扫描量热分析表明, SiO2的添加使SO2-4不易脱除,同时使锐钛矿TiO2向金红石相的转变温度降低.