Ru-Fe/C催化剂上邻氯硝基苯原位液相加氢性能

采用浸渍法制备Ru/C催化剂,并用于原位液相催化邻氯硝基苯(o-CNB)加氢合成邻氯苯胺(o-CAN)反应中.考察了浸渍顺序、助剂、还原温度、载体和助剂含量等因素对催化剂稳定性的影响.采用透射电子显微镜、X射线光电子能谱、傅里叶红外光谱和N2吸附-脱附等手段表征催化剂.结果表明,以15%Fe为助剂,活性炭为载体,制备得到的0.5%Ru-Fe/C催化剂经过523K氢气还原后o-CNB的转化率为99.7%,o-CAN的选择性达到98.7%,反应140h未出现明显失活.催化剂表面吸附CO导致中毒是失活的主要原因,同时对催化剂再生方法进行了探究.     

邻氯硝基苯在Pd/C催化剂上加氢反应机理及添加Cu对邻氯苯胺选择性的影响

本文研究了邻氯硝基苯在5%Pd/C催化剂上加氢为邻氯苯胺和苯胺的反应机理。结果表明,在常压下,邻氯苯胺和苯胺的选择性分别为~70%和~30%,且不随转化率增加而变化。在加压(1.0 Mpa)条件下,也有类似规律。因此,说明邻氯苯胺和苯胺分别是两个平行反应的产物。通过测定该反应各步骤的初始反应速率,进一步证实了这一结论。在认识反应机理的基础上,制备出可有效抑制脱氯的Cu-Pd/C双金属催化剂,在不加脱氯抑制剂的情况下,可使邻氯硝基苯加氢制备邻氯苯胺的选择性提高到96%以上。     

负载型镍基非晶态催化剂催化氯代硝基苯加氢合成氯代苯胺

分别以碳纳米管(CNTs), SiO_2, TiO_2, γ-Al_2O_3, TiO_2-SiO_2和活性炭(AC)为载体(M),以Ni和B为活性组分,采用浸渍-化学还原法制备了一系列负载型Ni-B非晶态合金催化剂(Ni-B/M).采用电感耦合等离子体光谱(ICP), XRD, TEM和DSC研究了Ni-B/CNTs的非晶性质,Ni的担载量及其热稳定性.将Ni-B/M用于催化三种氯代硝基苯液相加氢合成氯代苯胺的反应.结果表明,Ni-B/M在反应中表现出较高的活性和良好的选择性,其中Ni-B/CNTs可使三种氯代硝基苯的转化率均高于99.8%,加氢脱氯率小于3%.讨论了CNTs和Ni-B之间的相互作用对催化剂性能的影响.     

氯代苯胺液相催化加氢合成环己酮

提出了一种催化降解氯代苯胺高选择性合成环己酮的技术.在La修饰Pd/Al2O3催化剂作用下,通过催化加氢的方法实现了由多氯代苯胺(2,4,6-三氯苯胺和2,4,-二氯苯胺)高选择性地合成环己酮(不含环己醇).在优化的反应条件下,2,4,6-三氯苯胺加氢生成环己酮的转化率和选择性分别为100%和98.6%(没有检测到环己醇);2,4,-二氯苯胺加氢生成环己酮的转化率和选择性均为100%.氯代苯胺在Pd/La-Al2O3催化剂表面首先发生加氢脱氯/N-甲基化等反应生成苯胺、N-甲基苯胺和N,N-二甲基苯胺等中间产物,随后这些中间产物发生苯环加氢、氨基水解/醇解等反应得到环己酮;氯代苯胺上Cl元素的存在和体系中水的含量是影响环己酮选择性的重要因素.     

Fe3O4修饰的Pt-Ru/C纳米催化剂的制备及其在无溶剂条件下邻氯硝基苯选择性加氢的催化性能

采用浸渍法制备了一系列Pt/Ru质量比不同的Fe₃O₄修饰的Pt-Ru/Fe₃O₄/C催化剂, 运用透射电镜(TEM)、能量弥散X射线谱(EDX)、X射线光电子能谱(XPS)、X射线粉末衍射(XRD)等手段对Pt-Ru/Fe₃O₄/C一系列催化剂进行了表征, 并考察了Pt/Ru质量比不同对催化剂Pt-Ru/Fe₃O₄/C在无溶剂条件下催化邻氯硝基苯(o-CNB)选择性加氢制备邻氯苯胺(o-CAN)催化性能的影响. 研究结果表明, 催化剂的催化活性和对目标产物的选择性跟活性组分Pt、Ru比例有关. 随着Pt/Ru比例的减小, 目标产物o-CAN的选择性有所升高, 然而反应物o-CNB的转化率有所下降. 当Pt/Ru的质量比为2时, o-CNB的转化率降为76.5%, 而目标产物o-CAN的选择性仍然为100%. 与此同时, 我们还对Pt-Ru/Fe₃O₄/C催化剂高的催化活性和目标产物的高选择性可能的原因进行了分析.     

激光溅射法制备Pt/CNTs催化剂用于邻氯硝基苯的液相加氢反应

采用激光溅射法制备了碳纳米管负载铂(Pt/CNTs)催化剂, 并利用透射电子显微镜(TEM)、X射线能量散射谱(EDS)、X射线衍射(XRD)、X射线光电子能谱(XPS)等表征手段研究了Pt粒子在碳纳米管表面存在的状态、组成、结构等性质. 讨论了Pt/CNTs催化剂的不同制备条件对催化剂结构的影响, 并考察了催化剂对邻氯硝基苯液相加氢合成邻氯苯胺反应的加氢性能. 研究结果表明, 在激光电压为250 V, 绝对压力为300 Pa, 载体温度为25 ℃条件下制备的Pt/CNTs催化剂, 在不加脱卤抑制剂, 反应温度为60 ℃和氢气压力为1.0 MPa的条件下, 邻氯硝基苯转化率可以达到99.7%以上, 邻氯苯胺选择性可达到98.2%以上, 表现出较高的加氢性能和抑制脱卤性能.     

高分子稳定的铂胶体催化氢化邻氯硝基苯

以聚乙烯吡咯烷酮(PVP)为保护剂,甲醇为还原剂,甲醇-水为溶剂,制备了高分子稳定的铂胶体(PVP-Pt).以PVP-Pt催化邻氯硝基苯(o-CNB)的催化氢化反应,考察了反应温度、底物浓度、催化剂浓度等因素的影响.当反应温度为30℃,氢气压力为0.1 MPa时,o-CNB的转化率可达92.3%,邻氯苯胺的选择性可达76.9%.     

镍负载量对邻氯硝基苯加氢制邻氯苯胺Ni/TiO2催化剂性能的影响

 用等体积浸渍法制备了一系列不同镍负载量的负载型Ni/TiO2催化剂,并将其应用于邻氯硝基苯加氢制邻氯苯胺的反应. 采用N2吸附、 X射线衍射、程序升温还原、透射电镜、 H2化学吸附及间歇加压釜式反应器活性评价等方法,考察了镍负载量对Ni/TiO2催化剂的物化性质及邻氯硝基苯加氢反应性能的影响. 结果表明,随着镍负载量的增加, Ni/TiO2催化剂上邻氯硝基苯的转化率逐渐提高; 当镍负载量超过30%时,催化剂的活性和选择性不再明显变化. 当催化剂中镍负载量高于20%时,在温度343 K、 氢压1.0 MPa和催化剂/邻氯硝基苯质量比1/10的条件下反应210 min后,邻氯硝基苯的转化率和邻氯苯胺的选择性均高于99%, 催化剂具有良好的应用前景. 分析表明,影响Ni/TiO2催化剂性能的主要因素为催化剂表面镍晶粒的活性表面积以及载体TiO2与金属镍之间的强相互作用.     

聚合物稳定的Ru-Pt/γ-Al2O3双金属催化剂催化2,5-二氯硝基苯选择性加氢

 制备了以聚乙烯吡咯烷酮(PVP)稳定的 Ru-Pt/γ-Al2O3负载型双金属催化剂,用于2,5-二氯硝基苯中的硝基选择性加氢. 考察了催化剂还原方法,反应温度、压力、时间和添加金属离子对反应的影响. 结果表明,用乙醇还原的Ru-Pt/γ-Al2O3催化剂性能明显好于用其它方法还原的催化剂,在50 ℃和氢气压力1.0 MPa的条件下反应1 h,转化率为41.4%,生成2,5-二氯苯胺的选择性为63.5%. 如果在上述反应条件下向该催化体系中加入Sn4+离子,反应的活性和选择性则大幅度提高,转化率达100%,选择性为77.6%,延长反应时间至4 h,选择性可达99.3%,并且没有脱氯产物的生成.     

金属离子对Ru-Pt/γ-Al2O3催化剂上对氯硝基苯选择加氢反应的影响

 采用混合醇还原法制备了聚乙烯吡咯烷酮(PVP)稳定的Ru-Pt/γ-Al2O3双金属催化剂,考察了其催化对氯硝基苯(p-CNB)选择加氢反应的性能,探讨了反应温度、压力、第三金属离子的种类、添加量及添加方式对反应的影响. 结果表明,以Ru-Pt/γ-Al2O3为催化剂,在1.0 MPa和50 ℃的条件下反应1 h,p-CNB的转化率可达48.2%,生成对氯苯胺(p-CAN)的选择性为87.3%. 在反应体系中添加适量的Fe3+或Sn4+离子时,在相同的反应条件下,p-CNB的转化率和p-CAN的选择性分别提高到100%和99.0%. Fe3+或Sn4+的添加量及添加方式对p-CNB的转化率有较大的影响,加入Fe2+,Co2+和Ni2+离子也有利于提高催化剂的活性和选择性. Ru-Pt/γ-Al2O3催化剂体系对其它氯硝基苯的加氢反应也有明显的催化作用.     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

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。     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

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.