卤代芳胺合成的研究进展

本文综述了由卤代芳硝基物还原制备卤代芳胺的三种方法,并对几种还原方法的优缺点进行了对比和讨论,得出水合肼还原具有很好的应用前景。     

卤代芳胺合成的研究进展

本文综述了由卤代芳硝基物还原制备卤代芳胺的三种方法,并对几种还原方法的优缺点进行了对比和讨论,得出水合肼还原具有很好的应用前景。     

由卤代芳硝基物制备卤代芳胺的综述

综述了由卤代芳硝基物还原制备卤代芳胺的三类方法,对三类还原方法的优缺点进行了对比和讨论,重点介绍了第三类制备卤代芳胺的还原方法-催化加氢还原法,最后介绍了催化加氢还原卤代芳香硝基物的新方法及新领域。     

介孔碳负载纳米Pt高效催化卤代芳香硝基化合物选择性还原制卤代芳胺

卤代芳胺主要通过卤代芳硝基化合物选择性还原制备,但加氢过程中常伴随着不同程度的脱卤反应而降低反应的选择性。本文采用柠檬酸镁快速热解法制备的介孔碳材料(MC-c)做为载体,制备了MC-c负载的高分散Pt纳米粒子(Pt/MC-c),并将其用于多种卤代芳香硝基化合物选择性还原制卤代芳胺。研究结果表明,Pt/MC-c催化剂在选择性还原反应中表现出了较高的反应活性和100%的卤代芳胺选择性。邻氯硝基苯为模型反应物的循环实验表面,Pt含量为2%的2%Pt/MC-c催化剂在循环12次后,反应活性和选择性没有明显变化,仍然保持在78%和100%。表明制备的Pt/MC-c催化剂在卤代芳香硝基化合物选择性还原反应中具有优异的反应稳定性。优异的催化性能主要归因于Pt颗粒与介孔碳载体之间的协同作用。     

Pd/C催化剂催化邻硝基苯胺加氢制备邻苯二胺

卤代芳胺是重要的有机中间体,广泛应用于合成染料、农药、医药、香料及橡胶助剂等。卤代芳香硝基化合物通过液相催化加氢制备卤代芳胺的技术以其环境友好、产品质量稳定和工艺先进而受到重视。用负载型贵金属催化剂催化芳香硝基化合物选择加氢制备相应的芳胺有广泛的应用价值。采用邻硝基苯胺为原料,Pd/C为催化剂,低压催化加氢还原合成邻苯二胺,考察不同溶剂、反应压力、反应温度和反应时间对产物收率的影响。结果表明,在甲醇为溶剂、反应温度100 ℃、反应压力0.8 MPa和反应时间100 min条件下,邻苯二胺平均收率为97%。与传统硫化碱还原或铁粉化学法还原工艺相比,以甲醇为溶剂,Pd/C催化剂催化加氢法在减少废水和降低成本等方面有较大优势。     

过渡金属催化卤代芳烃胺化反应的研究进展

过渡金属催化卤代芳烃的胺化是合成芳胺化合物的重要方法,本文综述了近年来过渡金属催化卤代芳烃与胺等不同含氮化合物的胺化反应研究进展。钯和铜是近几年卤代芳烃胺化反应的热点,重点讨论了钯催化下卤代芳烃与各类胺反应以及铜催化下卤代芳烃胺化反应的研究进展。     

卤代芳硒在有机合成中的应用

综述了一类多功能合成试剂——卤代芳硒在有机合成上的应用。文章包括卤代芳硒的制备和硒氧化物的消除。选择性好,产率较高且反应条件温和。     

新的氨化-还原试剂--二烷基胺硼氢化锂(LAB)

介绍了一种新的氨化-还原试剂———二烷基胺硼氢化锂,讨论了它在卤代苯腈中的应用,其结果为o 卤代苄腈在与通用的新氨化-还原试剂反应得到相应的氨基苄胺。     

钯催化卤代芳烃的胺化反应研究

钯催化卤代芳烃胺化是形成CAr-N的重要方法。配体的发展扩展了底物的适用范围，提高了反应的选择性，实现了廉价易得的氯代芳烃的胺化，弱碱的使用提高了官能团的兼容性，因此Pd催化芳胺化广泛应用于合成芳胺类化合物。本文以卤代芳烃为线索，对钯催化偶联胺化反应的研究进展进行了综述和展望。     

卤代芳氧基酰氧基烃基膦酸及其酯的合成与生物活性

报道了以２,４－二氯苯酚、氯代乙酸或α－氯代丙酸乙酯为起始原料合成１２种卤代芳氧基酰氧基烃基膦酸或其酯的方法及目标化合物的除草活性,讨论了目标化合物的除草活性与其结构的对关关系。     

油溶性聚合物在稠油降黏中的研究进展

稠油黏度高、密度大,给开采运输带来巨大的挑战.常用掺稀、加热、乳化等方式对稠油降黏,但各种技术均存在不足和限制.近年来,油溶性降黏剂因其降黏效率稳定、成本较低及操作简便等优点而备受关注,展现出良好的应用前景.油溶性降黏剂大多是由降凝剂发展而来,主要包含3种基团——长链烷基、芳香环和极性基团.该文综述了油溶性稠油降黏剂的发展历程、基本现状、结构特点;分析了油溶性降黏剂中3种关键基团在降黏过程中的不同作用和前人在3种基团方向上的尝试;阐述了降黏机理及3种关键基团对降黏效果的影响;最后指出油溶性降黏剂的不足之处并对其发展趋势进行展望.     

Catalytic selective reduction of NO with propylene over Cu-Al2O3 catalysts: influence of catalyst preparation method

NO reduction to N₂ by C₃H₆ was investigated and compared over Cu-Al₂O₃ catalysts prepared by four different methods, namely, the conventional impregnation, co-precipitation, evaporation of a mixed aqueous solution, and xerogel methods. It was found that the catalyst preparation method as well as the Cu content exerts a significant influence on catalyst activity. For the catalysts prepared by the first three preparation methods, with the increase of Cu content from 5 to 15 wt%, the maximum NO reduction conversion decreased slightly, but the temperature for the maximum NO reduction also decreased. For the xerogel Cu-Al₂O₃, there was a significant decrease in NO reduction conversion with the increase of Cu content from 5 to 10 wt%. In the absence of water vapour, the Cu-Al₂O₃ catalyst prepared by the impregnation method exhibited the highest activity toward NO reduction. The purity of alumina support was found to be a crucial factor to the activity of the Cu-Al₂O₃ catalyst prepared by impregnation. In the presence of water vapour, a substantial decrease in NO conversion was observed for the Cu-Al₂O₃ catalysts prepared by the first three methods, especially for the impregnated Cu-Al₂O₃ catalyst. In contrast, the presence of water vapour showed only a minor influence on the xerogel 5 wt% Cu-Al₂O₃ and it showed the highest activity for NO reduction in the presence of 20% water vapour. The xerogel 5 wt% Cu-Al₂O₃ catalyst was also found to be less affected by a 5 wt% sulfate deposition than the Cu-Al₂O₃ catalysts prepared by other methods.     

5-硝基-1,10-邻菲罗啉还原合成5-氨基-1,10-邻菲罗啉的研究

综述了硝基化合物还原制备氮基化合物的主要方法。分别以氯化亚锡-盐酸、铁粉-硫酸、5％Pd／C-水合肼为催化加氢还愿体系,还原5-硝基-1,10-邻菲罗啉合成了5-氮基-1,10-邻菲罗啉。结果表明：钯炭催化剂与水合肼组成的还原体系具有较好的还原效果。     

Verwertung von Natriumsulfat

Utilization of sodium sulphate. Commercial sodium sulphate is usually obtained by crystallization and calcination. Processes for utilizing sodium sulphate that have previously been studied or used are mainly the following methods: electrochemical processes, conversion processes, and reduction processes. At present the first two groups of these three appear more advantageous than the reduction processes, which are technically complex and suffer from the formation of waste gases. The lower energy requirements of the conversion processes offer advantages over electrolytic methods. Only comparative cost estimates for the different processes could help one arrive at a sound evaluation.     

5-氨基水杨酸的合成方法

5-氨基水杨酸(5-ASA)是治疗炎症性肠病(IBD)的临床首选药物之一,对其制备工艺的研究具有重要的现实意义。笔者对合成5-ASA的主要方法:硝基还原法、Kolbe合成法、水杨酸偶氮物中间体还原法进行了综述,比较了3种方法在反应条件、收率、环保等方面的优缺点,并对今后的研究方向进行了展望。     

Time dependent diffusion in concrete—three laboratory studies

The rate of chloride diffusion into concrete decreases with time due to issues such as continued hydration and chloride binding. Data are presented from three projects where the specimens were continuously exposed to chloride solutions for periods ranging from 28 days to 3 years. Chloride profiles obtained from the specimens at various time intervals were used to calculate diffusion values using Crank's solution to Fick's second law. The time-dependant reduction coefficient, m, was determined using three methods, yielding different values. Since the reduction of calculated diffusion coefficients with time has great impact on service life predictions, and values are sensitive to the method used, it is imperative to also know how the diffusion and time-dependant reduction coefficients were obtained.     

制备方法对V_2O_5-WO_3/TiO_2选择性催化还原催化剂性能的影响

采用共沉淀法、溶胶-凝胶法和浸渍法制备了V2O5质量分数4%和WO3质量分数6%的V2O5-WO3/TiO2选择性催化还原催化剂,对比了3种方法制备的催化剂选择性催化还原NO性能。采用X射线衍射、热重、N2吸附-脱附和程序升温还原等对制备的V2O5-WO3/Ti O2催化剂的结构和性质进行表征,结果表明,共沉淀法制备的V2O5-WO3/TiO2催化剂具有更好的选择性催化还原NO活性和更大的比表面积,影响共沉淀法选择性催化还原NO活性的主要因素是催化剂的热稳定性、表面羟基数量、比表面积、粒径分布以及V、W与Ti之间的内在作用。