A MILD AND EFFICIENT CsOH-PROMOTED SYNTHESIS OF DITERTIARY PHOSPHINES

A mild and efficient method for the synthesis of ditertiary phosphines has been developed. In the presence of cesium hydroxide, molecular sieves, and DMF, various dihalides were coupled with diphenylphosphine at room temperature, and the results have demonstrated that this methodology offers a general synthetic procedure producing a variety of ditertiary phosphines in high yields.     

一种有效的制备聚乙二醇修饰氧化石墨烯的方法

为提高氧化石墨烯(GO)的生物相容性从而扩展其在高性能生物材料制备中的应用,采用甲苯-2,4-二异氰酸酯作为桥联剂,制备了四臂星型聚乙二醇修饰氧化石墨烯(GO-TDI-sPEG),该产物在水中仍然可以稳定分散.采用傅里叶红外光谱(FTIR)、拉曼光谱(Raman)、X-射线衍射(XRD)、原子力显微镜(AFM)、透射电子显微镜(TEM)和热重分析(TGA)对接枝产物进行表征.产物在2861 cm-1和1093 cm-1处出现的特征红外吸收表明sPEG已接枝到GO上.产物的Raman光谱中D模与G模信号变弱,且ID/IG值变化不大,说明sPEG改性后的氧化石墨物理结构没有发生变化.XRD曲线上产物衍射峰消失,表明经聚合物修饰后氧化石墨被完全剥离.TGA数据表明原始GO在约160℃开始发生热失重,经修饰后,大约在260℃开始热失重,热稳定性增加了约100℃.由TEM图片可以观察到GO及改性石墨烯产物剥离程度较高,且片上分布有较多聚合物点.且AFM图片显示GO的平均厚度大约为0.85 nm,接上聚合物后部分厚度增加到约1.2 nm.     

制备高比表面负载型催化剂的一种新方法

制备具有大比表面、适宜孔结构的催化剂一直是催化剂研究的重要课题之一.近年,氧化锆、氧化钛载体以其独特性能引起多方面的关注.然而,这两种载体不但本身比表面较小,而且在高温灼烧时比表面急剧下降,所以很难制成高比表面催化剂,极大地限制了它们的应用.本文提出一种制备高比表面负载型催化剂的新方法,它特别适用于TiO_2、ZrO_2.它是在以下两个想法的基础上提出的.(1)我们在工作中曾发现,将仲钼酸铵加到Ti(OH)_4中,经500℃、4小时焙烧,所得的MoO_3/TiO_2(MoO_3质量分数为13.0%)比表面可达133m~2·g~(-1).而用仲钼酸铵浸渍已晶化     

以除尘灰分离碳粉制备活性炭的新方法研究

利用除尘灰分离碳粉作原料,采用添加适量化学药品KOH的方法制备颗粒活性炭。研究了随着KOH加入量的变化,活性炭性能和对苯的吸附量的变化规律,以及KOH的加入量对活性炭的微晶结构和表面形貌产生的影响。并探讨了添加剂在活性炭制备的炭化和活化阶段的产生的影响。实验结果表明在KOH加入量为1.5%时,碘吸附值、比表面积和对苯的吸附量达到最高值,KOH过量反而对吸附性能有负面影响。     

RUTHENIUM-TPPTS CATALYZED REDUCTlON OF NITROBENZENE TO ANILINE——A HIGHLY SELECTIVE WATER-SOLUBLE CATALYST SYSTEM

The ruther ium catalvst complex formed from RuCl_3·3H_2O andthe water-soluble ligand tris-(sodium m-sulfophenyl)phosphine, TPPTS, hasbeen examined as a catalyst for the reduction of nitrobenzene to anilineunder water gas shift conditions. The reactions, which were conducted inaqueous methanol. were studied as a function of CO pressure and addedamine base The major product observed over the temperature range of100～150℃ was aniline (>90% yield abovc 130℃ ), with only minor amountsof the corresponding carbamate PhNHCO_2Me(<3%) and formanilide(<4%)being observed. Of the several amine bases examined in this reaction, Et_3Nhas been found to be superior in promoting the fastest rate of nitrobenzenereduction. Replacement of methanol by either THF or xylenes led to a drastic retardation in the amount of aniline produced.     

A NEW METHOD TO PREPARE CHITOSAN MEMBRANE AS A BIOMEDICAL MATERIAL*

This paper reports a new method to prepare chitosan membrane which could be used as a biomedical material.Addition of a fixation agent composed of alcohol, glycerol and potassium hydroxide can acceletate the sol-gel transformationprocess and hence shorten the prepedion perod. The present method takes about 6 h to get a flexible membrane with fineappearance. The physical and biological properties of the membrane were also investigated and compared with the membraneprepared by conventional method.     

PHOSPHORUS PENTASULFIDE AS A MILD,SELECTIVE REAGENT FOR THE REDUCTION OF SULFOXIDES TO SULFIDES

Abstract

It has been shown that phosphorus pentasulfide (P₄S₁₀) is a mild, effective reagent for the reduction of sulfoxides to sulfides and that this conversion can be achieved selectively in the presence of other reactive groups such as ketone, ester, amide, nitro and halogen. This reagent can be used in similar fashion for the efficient reduction of sulfilimines (in both the N-p-toluenesulfonyl and free NH forms). Phosphorus pentasulfide also appears to be a promising reagent for reducing selenoxides but is ineffective in reducing sulfones, sulfinates, or sulfites. The mechanistic evidence presented indicates a probable four-centre (Wittig-like) intermediate or transition-state for the reduction by P₄S₁₀.     

活性炭作为载体和还原剂对NO的还原作用

四种国产活性炭既作为载体又作为还原剂被用于ＮＯ还原反应，山楂核炭和山桃核炭作载体时ＮＯ还原转化率很高，椰壳炭和煤质炭作载体时ＮＯ还原转化率则较低，四种活性炭两－两分组现象可由其元素分析，ＮＨ３－ＴＰＤ、还原性及ＮＯ吸附量等结果来解释。另外ＣｕＯ／椰壳炭与ＣｕＯ／煤质炭的ＮＯ还原转化率的差别主要归于二者的ＮＯ吸附量不同，对ＣｕＯ／山楂核炭和ＣｕＯ／山桃核炭，ＮＯ还原转化率随反应温度的相对变化主要由其     

菲的电解还原

菲的电解还原胡明，刘旭光，王志忠（太原工业大学，太原０３００２４）关键词菲，有机电化学，电解还原近年来有机电解技术引入煤转化领域的研究已有过一些综述￣［１～６］。以多环芳烃为模型化合物，研究其在电解条件下的转化行为，从理论和实践上都将为煤及其加工产品...     

REDUCTION OF AZIDES TO AMINES OR AMIDES WITH ZINC AND AMMONIUM CHLORIDE AS REDUCING AGENT

ABSTRACT

Alkyl azides and acyl azides were reduced to the corresponding amines and amides with zinc and ammonium chloride as reducing agent under mild conditions in good to excellent yield.     

环戊烷选择性氧化用VPO催化剂的合成新方法

研究了ＶＰＯ催化剂时还原溶剂对ＶＰＯ的结构及催化性能的影响,ＶＰＯ的合成方法如下：（１）Ｖ２Ｏ５与Ｈ３ＰＯ４反应生成磷酸钒;（２）用不同的还原溶剂还原磷酸钒得到ＶＰＯ催化剂前身;（３）活化ＶＰＯ催化剂前身,研究的还原溶剂有;异丁醇,异丁醇－苯甲醇,异丁醇－石油醚和正己醇。结果表明,使用异丁醇－石油醚作还原溶剂,只能生成ＶＯＨＰＯ４．０．５Ｈ２Ｏ晶体;使用其它溶剂则会生成ＶＯ（Ｈ２ＰＯ４）２和ＶＯＨ     

ON THE ANIONS OF DIPHENYL 1-(4-NITROPHENYLAMINO)-1-ARYLMETHANE PHOSPHONATES1

Abstract

By means of UV spectroscopy it is shown that the anions derived of diphenyl 1-(4-nitrophenylamino)-1-arylmethane phosphonates are carbanions and not nitranions. This spectroscopical finding is corroborated by alkylation of the anions to give almost quantitatively the C-alkylated products.     

A NOVEL METHOD TO PREPARE CROSSLINKED POLYETHYLENEIMINE HOLLOW NANOSPHERES

A novel method to prepare crosslinked polyethyleneimine(CPEI)hollow nanospheres was reported.Uniform silica nanospheres were used as templates,3-aminopropyl trimethoxysilane(APS)was immobilized on the surface of silica nanospheres as couple agent.Aziridine was initiated ring-opening polymerization with the amino groups in APS to form polyethyleneimine(PEI)shell layer.1,4-Butanediol diacrylate was utilized to crosslink PEI polymeric shell.The silica nanospheres in core were etched by hydrofluoric acid to obtain hollow CPEI nanospheres.The hollow nanospheres were characterized by X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),and thermogravimetric analysis(TGA).     

SYNTHESIS OF DIOLS BEARING PHOSPHONATE GROUPS PART III. THIOLS USED AS STARTING MATERIALS

This article describes the synthesis of diols bearing a phosphonated group. The method used is the monoaddition of a thiol on unsaturated compounds. Two ways are possible depending on the species bearing either the phosphonated group or the diol function. First we added a thiol bearing a diol function onto dialkylallylphosphonates. Then a thiol bearing phosphonated groups was added onto an allylic diol. On the other hand we compared radical and UV additions. We also compared the reactivity of similar phosphonated compounds (dimethyl and diethyl phosphonates). All the reactions gave very good yields and the different products have been analyzed by NMR studies. Finally, we succeeded in the synthesis of the corresponding phosphonic diacids by the bromosilane method.     

FRAGMENTATION OF PRIMARY FLOCS IN EMULSIONS AND THE SUBSEQUENT REDUCTION OF COALESCENCE

In existing theories emulsion desiabilization is considered as the combined processes of irreversible flocculation and coalescence of dispersed droplets. This approach can be justified when the potential pit characterizing the energy of droplet interaction is sufficiently deep, i.e. excluding small droplet dimensions, strong electrosiatic repulsion and low electrolyte concentrations. For smaller droplet dimensions and stronger electrostatic repulsions the emulsion instability must be considered as a combined process of reversible flocculation and coalescence. In this paper a mathematical model that couples the kinetics of flocculation, coalescence and floe fragmentation is developed in order to quantify the kinetic instability of emulsions with charged submicron droplets. The characteristic limes for flocculation (Smoluchowski's time τ_c) for coalescence (coalescence time τ_c) and for disaggregation (doublet lifetimeτ_d) are considered model parameters. The mathematical model applies to the case when and τ_d<< τ_c, which corresponds to a situation with a small multiplet concentration compared to the concentration of doublets and a singlet-doublet quasi-equilibrium. It is established that at singlet-doublet quasi-equilibrium the rate of the decline in the total droplet concentration is described by second order kinetics in distinction to the exponential time dependence valid for coalescence at irreversible flocculation. The double disintegration reduces the entire coalescence rate, expressed as τ_sm/ τ_d. This reduction is very large at small values of Td. The mathematical model presented can hased on the spontaneous disintegration of doublets predict changes in emulsion stability for model systems and also for technologically important emulsions.     

青蒿素的锂铝氢还原

青蒿素在温和条件下进行锂铝氢还原时,除得到彻底还原的产物外,还生成部分还原的邻位羟基内醚。在剧烈的反应条件下则全部是彻底还原的产物。通过进一步的化学反应和相应的物理数据确定了上述两个反应产物的化学结构。     

载体对CO还原SO2到单质硫铁基催化剂性能的影响

研究了四种载体MgO ,α Al2 O3 ,γ Al2 O3 ,Ce γ Al2 O3 负载Fe催化剂上CO还原SO2 的反应。结果发现 ,以不同载体制备的催化剂上反应的活性和选择性具有相同的顺序 ,即Ce γ Al2 O3 >γ Al2 O3 >α Al2 O3 >MgO。BET表面积测试表明 ,比表面较大的载体有利于提高催化剂的活性 ,而XRD结果证明 ,催化剂的活性大小关键取决于反应过程中是否形成了催化活性相FeS2 ,只有生成FeS2 的催化剂才会在反应过程中表现出活性 ,TPR和TG实验证实 ,催化剂表面氧化还原能力越强越有利于形成FeS2 ,从而在反应过程中表现的活性也越高 ,Ce对γ Al2 O3 的改性一方面促进了反应过程中活性相FeS2 的形成 ,另一方面为反应提供了所需的氧空位 ,使整个反应表现出中间产物机理和氧空位机理的协同效应。     

大环酮的微生物还原

本文报道了细菌、放线菌和丝状真菌等11株对甾族化合物有脱氢或羟化能力的微生物,对环十四酮及其同系物的生物转化结果。层析纯产物经熔点、元素分析、气-液色谱、红外、核磁、质谱等鉴定,证明有半数菌部将大环酮还原为相应的大环醇,而未发现有α,β-脱氢产物。     

测定硝酸盐氮时镉粒预还原条件的改进

在试验的基础上对镉柱还原法测定硝酸盐氮的的一些不足之处进行了改进，使精密度、准确度和还原效率得到提高，并扩大了曲线测定范围。     

DEVELOPMENT OF A PLAQUE REDUCTION ASSAY AND APPLICATION TO THE STUDY OF PSORALEN-DAMAGED DNA

Abstract— We have developed a procedure called a plaque reduction assay to assess the biological activity of duplex circular DNA modified by covalent adduct formation with psoralen derivatives. The replicating form (RF) of bacteriophage DNA modified by photochemical addition of a psoralen derivative was introduced into bacterial cells using the CaCI₂ transfection method. The transfected cells. plated upon a confluent lawn of cells permissive for the bacteriophage in the inoculum, provided a measure of the reduction in infectivity of the RF DNA which resulted from its covalent modification. Use of this assay is illustrated in studies which screened and compared the activities of several recently synthesized psoralen derivatives. We describe two new compounds. β-(8-psoralenoxy)-ethanol and β-(8-psoralenoxy)ethylamine that are significantly more active than either 8-methoxypsoralen or trioxsalen in the biological assay