活化硅胶表面Fe3+的担载及其对甲醛的催化氧化

硅胶颗粒经过400 ℃高温活化后与四氯化硅在无水四氢呋喃溶剂中反应制得氯化硅胶.氯化硅胶再经乙酰胺修饰,制备得到表面含羰基和氨基的硅胶修饰体.此组装体具有良好的配位能力,能够与Fe³⁺进行配位,从而得到表面催化活性点均匀分布的负载型催化剂.该催化剂对甲醛催化氧化具有良好的催化性能,最高催化效率高达91.3%.     

咪唑修饰硅胶配位固载锰(Ⅲ)卟啉对环己烷空气氧化的催化作用

应用3-氯丙基三甲氧基硅烷和咪唑成功地对硅胶表面进行了修饰,并通过咪唑基纵轴配位方式固载了四苯基锰(Ⅲ)卟啉.在无任何外加溶剂及共还原剂的条件下,应用此高分子金属卟啉作为催化剂,选择性地催化空气氧化环己烷为环己酮和环己醇.研究结果表明,与未固载金属卟啉相比,固载金属卟啉具有更高的催化活性和催化选择性,反应具有更高的酮醇比,催化剂的稳定性有了较大的提高,便于回收和重复使用.另外还探讨了载体在此催化体系中对催化性能的影响.     

聚合物配位体络铑催化剂的合成及对二异丁烯氢甲酰化反应的催化性能研究

本文用含有多胺、多(胺基膦)和单齿的胺基膦、亚磷酸酯等配位基团的功能基化交联聚苯乙烯与二氯四羰基二铑反应得到了10种聚合物配位体络铑催化剂。用这些催化剂进行了二异丁烯的催化氢甲酰化反应(反应条件:110℃;100,80,60kg/cm~2;H_2/CO=1:1;6h;苯为溶剂),大多数催化剂表现出了良好的催化性能。催化剂的红外光谱证明了聚合物多胺配位体与铑活性中心之间具有多齿配位结构。文中还对催化过程的铑脱落现象进行了研究,讨论了配位体结构与铑脱落量及催化活性的关系,测定了铑脱落量与催化剂使用次数关系的曲线,考察了反应条件及外添加试剂对铑脱落的影响,并提出了催化剂可能的铑脱落机制。     

三氟化硼修饰载体负载茂金属催化乙烯聚合

用BF3对载体硅胶和氧化铝进行了表面修饰,考察了修饰的载体负载茂金属催化剂后催化乙烯聚合的特性.研究表明,用BF3修饰过的载体负载二氯二茂锆催化乙烯的聚合,聚合活性有较大提高,具有工业应用前景,并且提出了这一催化体系的负载机理.     

配位负载金属卟啉的合成及催化氧化环已烷的性能研究

合成了三种与咪唑配体键合的新型载体，并通过其与四苯基卟啉铁和卟啉锰配位得到了改性的负载金属卟啉催化剂。讨论了它们在催化氧化环己烷反应中的稳定性、活性等，结果表明配位负载方式明显提高了金属卟啉的稳定性，其中硅胶配位负载锰卟啉还具有较高的活性。     

贵金属纳米粒子修饰碳纳米管的研究

碳纳米管具有独特的一维管状结构和优异的电、光、热和力学性能,是药物和纳米催化剂的理想载体。将具有独特光、电、磁和催化性能的贵金属纳米粒子负载在碳纳米管的表面,形成的碳纳米管/贵金属纳米粒子复合物不仅兼有两种纳米材料的优异性能,还可能产生新的特性,在催化、储能、燃料电池、电子器件和传感器等领域均有广阔的应用前景。本文主要从共价修饰和非共价修饰两种策略出发,综述了贵金属纳米粒子修饰碳纳米管的制备方法和研究进展。其中用天然高分子包覆的碳纳米管表面具有很好的贵金属配位结合能力,得到的纳米复合物具有良好的水分散性和生物相容性,在载药、生物传感器和肿瘤诊断治疗等生物领域具有明显的优势。     

高分子膦-钯络合催化剂的氢化催化活性和稳定性的考察

本文报道高分子膦-钯络合催化剂的合成及对催化剂催化加氢的活性、稳定性进行考察的结果。与文献对比表明,高分子膦-钯络合催化剂具有良好的稳定性和催化活性,膦化物不失为一类优良的配位体。     

用于乙炔氢氯化反应的活性炭负载铋无汞催化剂

采用浸渍法制备了活性炭负载铋无汞催化剂,并通过X射线衍射、氮气物理吸附、透射电镜、扫描电镜和X射线电子能谱等方法对催化剂进行了表征。对催化剂进行了催化乙炔氢氯化反应性能的研究,结果表明,催化剂对乙炔氢氯化反应具有良好的催化性能,活性组分主要以BiOCl的形式存在于催化剂表面。反应过程中积碳的产生使得催化剂活性有所降低。     

用于乙炔氢氯化反应的活性炭负载铋无汞催化剂(英文)

采用浸渍法制备了活性炭负载铋无汞催化剂,并通过X射线衍射、氮气物理吸附、透射电镜、扫描电镜和X射线电子能谱等方法对催化剂进行了表征。对催化剂进行了催化乙炔氢氯化反应性能的研究,结果表明,催化剂对乙炔氢氯化反应具有良好的催化性能,活性组分主要以BiOCl的形式存在于催化剂表面。反应过程中积碳的产生使得催化剂活性有所降低。     

接枝微粒PGMA／SiO2固载的金属卟啉仿生催化剂的制备

采用"接枝"法将甲基丙烯酸缩水甘油酯(GMA)接枝聚合到硅胶微粒表面,通过环氧键与羟基的开环成醚反应,进而将小分子的对羟基苯基卟啉化学键合在接枝微粒PGMA/SiO2表面,再与金属锰配位,从而制得了PGMA/SiO2固载的金属卟啉仿生催化剂(MnP-PGMA/SiO2);并用红外光谱法和原子吸收光谱法进行了表征;重点研究了对羟基苯基卟啉在接枝微粒PGMA/SiO2表面键合反应的规律;初步考察了MnP-PGMA/SiO2对分子氧氧化乙苯为苯乙酮的催化作用。实验结果表明:在键合反应中以4.5mL三乙胺为催化剂,在70℃下反应8h,可制得卟啉键合量为69.36μmol/g的键合微粒HPP-PGMA/SiO2;HPP-PGMA/SiO2与锰配位时,在64℃下反应8h,得到锰有效配位程度为92.34%的固体催化剂MnP-PGMA/SiO2。在催化分子氧氧化乙苯为苯乙酮的过程中,固体催化剂MnP-PGMA/SiO2具有高的催化活性。     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

Acid hydrolysis of carboxymethylcellulose of low degree of substitution

Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.     

Study of hydration of two cements of different strengths

Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, M_o, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700^oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.     

Estimation of Kinetic Parameters of Thermal Oxidation of Ilmenite

The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe₂O₃. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mechanism of action of base-catalyzed oxygenation of phenol derivatives

Cyclopropyl derivative of 2,6-di-tert-butylphenol is synthesized as a probe to investigate the mechanism of base-catalyzed autooxidation of phenol derivatives. Our study indicates that one electron reduction of molecular oxygen from phenolate gives phenoxyl radical 3, a key intermediate of autooxidation. The coupling of phenoxyl radical and superoxide radical gives peroxylate anion 4 and produces the final epoxy alcohol adduct 6.     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

化学计量中不确定度评定研究进展

测量不确定度是表征合理地赋予被测量之值的分散性的参数。本文针对化学计量不确定度评定基础模型仅适用于线性模型、概率分布为正态分布或缩放位移t分布等局限,介绍了近年来不确定度评定的研究热点:蒙特卡罗方法(Monte Carlo Method,MCM),不确定度评定的来源、评定概念、评估方法及其发展过程,扩大了测量不确定度评定与表示的适用范围。