Synthesis and antibacterial activity of some 5-hydroxy-5-trifluoromethyl-4,5-dihydropyrazol-1-thiocarboxamides, 3-trifluoromethylpyrazol-1-thiocarboxamides and 4-aryl-2-(5(3)-trifluoromethyl-1-pyrazolyl)thiazoles

5-Hydroxy-5-trifluoromethyl-4,5-dihydropyrazol-1-thiocarboxamides 3 and 3-trifluoromethylpyrazol-1-thiocarboxamides 4, regioselectively obtained by the condensation of trifluoromethyl-β-diketones with thiosemicarbazide under neutral and acidic conditions, on further reaction with phenacyl bromides 5 afforded 4-aryl-(5-trifluoromethyl-pyrazol-1-yl)thiazoles 6 and 4-aryl-(3-trifluoromethyl-pyrazol-1-yl)thiazoles 7, respectively. Five 4,5-dihydropyrazoles (3a–e) and two pyrazolylthiazoles (6a and 6c) were tested against one Gram-positive and one Gram-negative bacteria to assess their in vitro antibacterial activity. Compounds 3a, 3b and 3e showed moderate antibacterial activity against Gram-positive bacterium, Bacillus pumilus.     

Development of a fully automated sequential injection solid-phase extraction procedure coupled to liquid chromatography to determine free 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-methoxybenzophenone-5-sulphonic acid in human urine

2-Hydroxy-4-methoxybenzophenone and 2-hydroxy-4-methoxybenzophenone-5-sulphonic acid, commonly known as benzophenone-3 (BZ3) and benzophenone-4 (BZ4), respectively, are substances widely used as UV filters in cosmetic products in order to absorb UV radiation and protect human skin from direct exposure to the deleterious wavelengths of sunlight. As with other UV filters, there is evidence of their percutaneous absorption.This work describes an analytical method developed to determine trace levels of free BZ3 and BZ4 in human urine. The methodology is based on a solid-phase extraction (SPE) procedure for clean-up and pre-concentration, followed by the monitoring of the UV filters by liquid chromatography-ultraviolet spectrophotometry detection (LC-UV). In order to improve not only the sensitivity and selectivity, but also the precision of the method, the principle of sequential injection analysis was used to automate the SPE process and to transfer the eluates from the SPE to the LC system. The application of a six-channel valve as an interface for the switching arrangements successfully allowed the on-line connection of SPE sample processing with LC analysis.The SPE process for BZ3 and BZ4 was performed using octadecyl (C18) and diethylaminopropyl (DEA) modified silica microcolumns, respectively, in which the analytes were retained and eluted selectively. Due to the matrix effects, the determination was based on standard addition quantification and was fully validated. The relative standard deviations of the results were 13% and 6% for BZ3 and BZ4, respectively, whereas the limits of detection were 60 and 30 ng mL⁻¹, respectively. The method was satisfactorily applied to determine BZ3 and BZ4 in urine from volunteers that had applied a sunscreen cosmetic containing both UV filters.     

4－羟基－2，5－二甲基－3（2H）呋喃酮的合成

总结了食品增香剂４－羟基－２．５－二甲基－３（２Ｈ）呋喃国的合成方法，包括近期的合成研究进展，对一些合成方法的优缺点作了评述。参考文献２８篇。     

The synthesis and structure of La5Pb3Z,Z  N,O. Interstitial derivatives of a Cr5B3-Type structure

Suitable proportions of La, La₄Pb₃ and La₂O₃ or LaN reacted in pressed pellets at 1050°–1250°C result in high yields of the title compounds. Single crystal X-ray studies of the oxide show it to be an isopointal, interstitial derivative of the Cr₅B₃ structure (I4/mcm, Z = 4, a = 8.6895(2) Å, c = 14.540(1) Å, R/R_w = 3.0/3.5%). Oxygen or nitrogen atoms are bound in (La2)₄ tetrahedra within chains along (0, 1 /2, z). Negligible dimerization of the type characteristic of Cr₅B₃ is indicated by the Pb2? Pb2 separation, 3.550(1) Å. The structure is compared with other related examples.     

SmI2-Mediated 3-exo-trig cyclisation of δ-oxo-α,β-unsaturated esters to cyclopropanols and derivatives

In the presence of samarium diiodide and a proton source, δ-oxo-γ,γ-disubstituted-α,β-unsaturated esters of general formula R-CO-C(R′,R′)-CHCH-CO₂Bn readily cyclise to trans-cyclopropanol products and/or lactones derived from the cis isomers. For R=aryl, good stereoselectivities (ca 90%) in favor of the alcohols are generally obtained while a mixture of alcohols and lactones is obtained with R=alkyl or H. For R=cyclopropyl, the lactone is exclusively obtained in more than 90% yield. A mechanistic rationalisation of these variations of diastereoselectivity is proposed.     

Lipase-catalyzed resolution of 5-acetoxy-1,2-dihydroxy-1,2,3,4-tetrahydronaphthalene. Application to the synthesis of (+)-(3R,4S)-cis-4-hydroxy-6-deoxyscytalone, a metabolite isolated from Colletotrichum acutatum

(+)-cis-4-Hydroxy-6-deoxyscytalone, a natural product bio-synthesized by Colletotrichum sp., has been prepared and its absolute configuration confirmed as 3R,4S, the key step being a kinetic racemic resolution of a cis-diol easily obtained from commercial 1,2,3,4-tetrahydronaphthalen-1,5-diol. Four lipases and different reaction conditions were tested in order to obtain the best yield and enantiomeric excess. Confirmation of absolute configuration was made by NMR using a single-derivatization low-temperature procedure and MPA as the auxiliary reagent.     

V2O5-Sb2O3-TiO2催化剂 低温NH3还原NO及其抗H2O和SO2毒化性能

浸渍法制备了催化剂V₂O₅-Sb₂O₃-TiO₂,考察了V₂O₅、Sb₂O₃负载量、pH值和焙烧温度对催化剂V₂O₅- Sb₂O₃-TiO₂低温氨选择性催化还原(SCR)NO活性的影响;同时,考察了催化剂V₂O₅-Sb₂O₃-TiO₂抗H₂O和SO₂毒化性能。结果表明,V₂O₅和Sb₂O₃负载量分别为5%和2%、焙烧温度为400℃、pH值为4时,催化剂SCR活性最好,反应温度220℃时,可达97%。Sb₂O₃的加入不仅能增强V₂O₅/TiO₂的催化活性,而且能明显提高催化剂的抗H₂O和SO₂毒化性能。SO₂、NO吸附暂态反应和TG-DTG测试表明,Sb₂O₃的促进机制主要是促进了催化剂在SO₂存在条件下对NO的吸附,同时,减弱了硫酸铵盐与催化剂之间的相互作用,硫酸铵盐更容易分解。     

CeCl3·7H2O-NaI catalyzed intramolecular addition reactions of 7-hydroxy-1,3-dienes: a facile approach to hexahydrobenzofurans and tetrahydrofurans

CeCl₃·7H₂O-NaI effectively catalyzed intramolecular cyclization of cyclic 7-hydroxy-1,3-dienes, yielding hexahydrobenzofurans in diastereoselective fashion. This cyclization has been applied to synthesize tetrahydrofurans from acyclic 7-hydroxy-1,3-dienes.     

Microwave assisted rapid,catalyst-free,and efficient synthesis of a new class of diversely functionalized 3-hydroxy-2-oxindole scaffolds under aqueous reaction media

An efficient and rapid synthesis of a new class of diversely functionalized 3-substituted, 3-hydroxy-2-oxindoles scaffolds in catalyst-free conditions is described by the reaction of 1,3-diketone with isatins under microwave irradiation in aqueous medium. The generality of the reaction to afford the γ regioselective aldol addition products is well demonstrated by screening different structurally varied 1,3-diketone nucleophiles as well as isatin electrophiles. Simple reaction condition, good isolated yield of the product, and environmentally benign medium are attractive features of the present protocol.     

纳米负载型V_2O_5-WO_3/TiO_2催化剂碱中毒及再生研究

实验制备了陶瓷颗粒为骨架的纳米级V2O5-WO3/TiO2(C)催化剂。采用浸渍法模拟碱金属中毒,研究了中毒及再生对催化剂脱硝活性的影响,运用XRD、FT-IR、H2-TPR、XPS技术表征分析了碱金属对催化剂的失活作用。实验表明,碱金属能使催化剂活性降低,钾的毒性大于钠。FT-IR结果显示,催化剂以Lewis酸作为活性酸位。H2-TPR、XPS结果表明,钾的加入降低了催化剂的氧化能力,主要影响了催化剂表面的吸附氧。采用单纯的水洗方法并不能提高催化剂活性,而酸洗再生后催化剂在较高反应温度下活性得到较好的恢复。     

NO-NH_3-O_2 reaction catalyzed by V_2O_5/AC at low temperatures——Effects of SO_2, V_2O_5 loading and reaction temperature

The effects of SO2, V2O5 loading and reaction temperature on the activity of activated carbon supported vanadium oxide catalyst have been studied for the reduction of NO with NH3 at low temperatures (150-250℃). It is found that SO2 significantly promotes the catalyst activity. Both V2O5 loading and reaction temperature are vital to the promoting effect of SO2. The catalysts with V2O5 loadings of 1 -5 weight percent have a positive effect on the promotion of SO2, while the catalysts with V2O5 loadings of above 7 weight percent have not such an effect or show a negative effect. At lower temperatures (<180℃) SO2 poisons the catalyst but at higher temperatures promotes it. The reason of the SO2 promotion was also discussed; it may results from the formation of SO42- on the catalyst surface, which increases the surface acidity and hence the catalytic activity.     

The regioselectivity of the addition of benzeneselenyl chloride to 7-azanorborn-5-ene-2-yl derivatives is controlled by the 2-substituent: new entry into 3- and 4-hydroxy-5-substituted prolines

The electrophilic addition of benzeneselenyl chloride to the alkene moiety of 7-azabicyclo[2.2.1]hept-5-en-2-yl derivatives has been studied. With camphanates 8 and 9N-Boc-5-endo-chloro-6-exo-phenylseleno-7-azanorborn-2-yl camphanates 10 and 11 are obtained with high regioselectivity due to a steric control. With N-Boc-7-azanorbor-5-en-2-one (2) the corresponding 6-endo-chloro-5-exo-phenylseleno derivative 15 is obtained in high yield due to a kinetic control attributed to the electron-releasing ability of the homoconjugated carbonyl group. Bicyclic adducts 10 and 11 and 15 are readily converted into 4-hydroxy-(14) and 3-hydroxy-5-substituted proline derivatives 19, respectively.     

Bifunctionalized allenes. Part XXIV. Competitive electrophilic cyclization of 5-(dimethoxyphosphoryl)-alka-3,4-dienoates leading to 2,5-dihydro-1, 2-oxaphospholes and 5,6-dihydro-2H-pyranes

Abstract

We report herein a study on the competitive electrophilic cyclization of 5-(dimethoxyphosphoryl)-alka-3,4-dienoates involving 5-endo-trig and 6-endo-trig mode cyclizations. Reaction with electrophiles produces mixtures of the 2-(2-oxo-2,5-dihydro-1,2-oxaphosphol-5-yl)-alkanoates and (6-oxo-5,6-dihydro-2H-pyran-2-yl)-phosphonates by competitive electrophilic cyclization due to the participation of the neighboring phosphonate and carboxylate groups.     

SiO2改性的V2O5-MoO3/ TiO2催化剂抗碱中毒性能研究

以陶瓷为骨架,用溶胶凝胶法和浸渍法制备了V₂O₅-MoO₃/ TiO₂催化剂,并用SiO₂进行改性。采用浸渍法模拟碱K中毒,研究了SiO₂改性前后催化剂中毒脱硝效率的变化,并通过BET、H₂-TPR、NH₃-TPD等技术手段对催化剂进行了表征。结果表明,加入SiO₂后,催化剂的比表面积明显提高。SiO₂改性后新鲜催化剂还原温度向低温方向迁移10 ℃左右,氧化还原能力得到了提高,其表面酸强度和酸量也得到较大的提高。反应评价结果表明,SiO₂改性可以提高催化剂抗碱中毒的性能。     

商业V_2O_5-WO_3/TiO_2烟气SCR脱硝催化剂CaSO_4中毒机理研究

基于商业V_2O_5-WO_3/Ti O_2脱硝催化剂,设计了两种模拟Ca SO_4中毒的方法,通过比表面积测定(BET)、X射线衍射(XRD)、程序升温还原(H_2-TPR)、扫描电子显微镜(SEM)、原位漫反射傅里叶变换红外光谱(in situ DRIFTS)等表征技术并结合固定床脱硝性能测试平台,对中毒前后催化剂的微观结构、氧化还原能力及表面性质的变化与脱硝活性进行了对比研究,探索硫酸钙中毒机理。研究表明,Ca SO_4会堵塞催化剂孔径,孔径小于2.7 nm和孔径大于17.8 nm时Ca SO_4的影响更大,从而使催化剂的比表面积和孔体积变小;Ca SO_4中毒会导致Brnsted酸位数量和强度的降低,同时Lewis酸强度也会减弱,从而阻碍了NH_3的吸附,Ca SO_4引起催化剂氧化还原能力的降低。     

Reaction of a 5α-bromo-6β,19-epoxysteroid with BF3·Et2O/Ac2O: An evidence of a cyclic bromonium cation

Treatment of 3β-acetoxy-5-bromo-6β,19-epoxy-5α-androstan-17-one with Ac₂O and BF₃·OEt₂, produced the cleavage of the epoxy moiety and migration of the bromine atom to afford 3β,19-diacetoxy-6α-bromo-5-hydroxy-5β-androst-17-one in high yield.     

钠盐对V_2O_5-WO_3/TiO_2催化剂NH_3-SCR反应活性的影响

采用浸渍法制备了V_2O_5-WO_3/TiO_2催化剂,并通过浸渍不同浓度的Na_2SO_4和NaCl,研究了不同的钠盐种类及含量对催化剂NH_3-SCR反应活性的影响,以考察催化剂的抗碱性,并采用BET、XRD、XPS、FT-IR和NH_3-TPD等测试技术对催化剂进行了结构与性能表征.研究结果表明钠盐降低了催化剂的比表面积,导致催化剂表面V~(5+)=O和V-OH酸性位点数量以及表面化学吸附氧含量降低,从而降低了催化剂的反应活性.催化剂钠盐中毒后NO转化率显著降低,脱硝温度窗口变窄.     

1—（2—羟基—3,5—二硝基苯基）—3—［4—（苯基偶氮）苯基］—三氮烯与汞的显色反

研究了1-（2-羟基-3,5-二硝基苯基）-3-[4（苯基偶氮）苯基]-三氮烯（HDNPAPT）试剂与汞离子的显色反应。在非离子表面活性剂TritonX-100存在下,pH10．3的NH3·H2O-NH4Cl介质中,汞与HDNPAPF形成1：4的红色络合物,表观摩尔吸光系数ε525＝1．63×105·mol-1·cm－1,汞离子浓度在0～0．64mg/L范围内符合比尔定律。方法应用于废水中微量汞的测定。     

Highly effi cient and regioselective thiocyanation of aromatic amines,anisols and activated phenols with H2O2/NH4SCN catalyzed by nanomagnetic Fe3O4

A new method employing magnetic nanoparticles Fe3O4 as a catalyst and H2O2 as a green oxidant is developed for the oxidative thiocyanation of aromatic amines, anisols and activated phenols with high yields under mild reaction conditions. The catalyst could be easily recovered from the reaction mixture using an external magnet and reused in several reaction cycles without loss of activity.     

Two-stage catalytic system of Sn/Al2O3 and Pt/Al2O3for NO reduction by propene in lean conditions

The Pt/Al₂O₃, Sn/Al₂O₃catalysts were prepared by the single sol-gel method. The two-stage Sn/Al₂O₃and Pt/Al₂O₃catalyst in series for NO reduction with propene were investigated. The coexistance of water vapor enhanced the activity at medium temperature of 300-400^oC, and the NO conversion was above 50% at 225 to 500^oC even in the presence of water vapor and SO₂. This revised version was published online in August 2006 with corrections to the Cover Date.