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杨木快速裂解过程机理研究 总被引:8,自引:2,他引:6
将现代化学分析领域中重要的分析手段-裂解气相色谱法应用于对杨木 快速裂解过程机理的研究。通过系统考察裂解温度400-800℃、裂解挥发性产物停留时间0.6-4s。升温速率改变对杨木快速裂解气、液、固产物以及气相组分产率分布的影响,研究杨木快速裂解过程的反应机理,分析获得最大产油率的工艺操作条件。结果表明,杨木裂解过程中主要存在着生成焦油和生成焦炭两个反应的竞争和一个焦油二次裂化的连串反应,裂解温度、挥发性产物停留时间、升温速率决定着哪一种反应占据主要,从而得到安全不同的产物分布。 相似文献
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薄层色谱和柱色谱是基础有机化学实验教学中的重要内容。文章通过对经典实验装置的改进,减少了有机溶剂的使用量,减少了环境污染,缩短了实验时间,丰富了教学内容。 相似文献
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有机化学实验教学是有机化学课程非常重要的组成部分,然而部分有机化学实验对仪器设备要求高,而且在实验安全方面存在着很大的风险。通过虚拟仿真技术实现有机化学实验场景的模拟和再现,可以保障在安全可操作的环境下完成教学任务。同时还能丰富教学内容、激发学生兴趣,提高教学效果。本文以丁基锂的制备与反应实验为例,初探虚拟仿真技术在有机化学实验教学中的应用。 相似文献
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单萜烯是工业和大气环境中一类重要的化合物。文章选择一系列单萜烯与硫酸溶液反应,产物种类差别不大,产物含量很大不同。从实验结果中可以得出:在相同的反应条件下,a-pinene的反应活性是最大的。通过ESI-MS检测产物分子量,主要分子量为136,所以单萜烯在酸性条件下主要发生重排异构反应。 相似文献
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在一定的工艺条件下,流动反应器内物料的返混影响着串联反应的产物分布.本文分别对串联反应在平推流管式反应器和完全混合流釜式反应器中各组分的分布规律进行了研究,通过对两种反应器进行比较,给出反应器选择和在实际生产中反应器设计及操作方式确定的建议. 相似文献
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While chemical efficiency relies on several factors, the multicomponent reaction (MCR) approach was considered as a powerful synthetic tool for preparing target molecules of biological relevance in an efficient manner. Four classes of new bioactive molecules were designed and synthesized by asymmetric MCRs, in some cases with the cooperation of polymer-assisted solution-phase (PASP) technique. These include (a) C-glycosyl dihydropyrimidines and dihydropyridines via Biginelli and Hantzsch cyclocondensations, (b) C-glycosyl beta-amino acids via Mannich- and Reformatsky-type reactions, (c) C-glycosyl beta-lactams via Staudinger reaction, and (d) heterocyclic alpha-amino acids (glycine and alanine) via the Biginelli and Hantzsch reactions. 相似文献
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多组分化学反应具有操作简单、高效率和高原子经济性等优点,是一类重要的收敛性合成方法。三氟甲磺酸盐作为新型Lewis酸催化剂有极高的耐热性和耐氧化还原性,水相有机相均可催化,因温和、环境友好、可循环使用等特点而受到广泛关注。利用三氟甲磺酸盐催化多组分化学反应已经成为绿色化学的重要手段之一。简要总结了三氟甲磺酸盐催化剂在Strecker反应、Ha-ntzsch反应、Biginelli反应、Mannich反应、Passerini反应和Ugi反应等人名反应中的应用情况,并对其面临的挑战和机遇进行了讨论和展望。 相似文献
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Córdova MO Flores Ramírez CI Bejarano BV Arroyo Razo GA Pérez Flores FJ Tellez VC Ruvalcaba RM 《International journal of molecular sciences》2011,12(12):8575-8580
In this work, the results of a study comparing the use of irradiation from different regions of the infrared spectrum for the promotion of several organic reactions, are presented and discussed. This use of eco-conditions provides a green approach to chemical synthesis. A set of ten different organic reactions were evaluated, including the Knoevenagel, Hantzsch, Biginelli and Meldrum reactions. It is important to highlight the use of a commercial device that produces infrared irradiation in the near infrared region and its distribution by convection providing heating uniformity, significantly reducing reaction times, achieving good yields and proceeding in the absence of solvent. It is also worth noting that a variety of different reactions may be performed at the same time. Finally, the products obtained were identified using TLC, together with corresponding MS-data, complementarily in comparison of NMR (1)H and (13)C data with literature information. 相似文献
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Solid acids comprising 12-tungstophosphoric acid and 12-tungstosilicic acid anchored on to metal oxide (ZrO2), zeolites (Hβ and HZSM-5), and mesoporous material (MCM-41) were synthesized, characterized and used as the catalysts. A solvent free green route to carry out the Biginelli cyclocondensation reaction is described over synthesized catalysts. The method provides an efficient and much improved protocol of Biginelli reaction in terms of solvent free conditions, high yields up to 98 %, very short reaction time of 15 min, and simple work-up procedure. Based on the above study a best catalyst among all is proposed and is recycled up to four times without any significant change in % yields of the product. Another important feature of this method is survival of a variety of functional groups under the reaction conditions. 相似文献
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Urease is a superior biocompatible catalyst for switching from the Biginelli reaction to urea-based synthesis of 1,4-dihydropyridines in water, where 100% switching occurs at 0.02 g/mL of enzyme. Hantzsch reaction with ammonium acetate (NH4OAc) is inefficiently catalyzed by urease (70%, 4 h), and heavy metal ions inhibit the urease-catalyzed reactions with urea or NH4OAc. Promotion of the urea-based Hantzsch reaction by urease and its inhibition with Hg2 + supports specificity of urease for in situ generation of ammonia, whereas the role of urease in further transformations is not so specific. The features of this enzymatic method are reusability, mild reaction conditions, biocompatibility, generality, and high yield of products. 相似文献
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Sunil R. Mistry Rikesh S. Joshi Suban K. Sahoo Kalpana C. Maheria 《Catalysis Letters》2011,141(10):1541-1547
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A series of dihydropyrimidin-2(1H)-one (DHPM) belongs to one of the important class of therapeutic and pharmacological active compound, were synthesized through the multicomponent reactions (MCRs) of aldehydes, ethyl acetoacetate and urea, followed by the heterogeneous catalyzed Biginelli reaction. In the present endeavour, medium (ZSM-5) and large pore zeolites (Y, BEA and MOR) as well as dealuminated zeolites BEA, were studied as catalysts. An excellent activity for DHPMs synthesis is achieved by optimizing accessibility of the reactants to the active sites and the surface polarity of zeolite catalysts. Moreover, the mechanism of Biginelli reaction was studied by means of GAUSSVIEW energy calculations of adsorbed acylimine intermediate on zeolite by using the density functional method (DFT). 相似文献17.
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In this communication, four materials (CeO2, CeO2(Cu), MnOx, and MnOx(Cu)) were prepared, characterized and tested as catalysts, in solvent-free conditions, for the multicomponent Hantzsch reactions to obtain alternatively the 1,4-dihydropyridine or 2-phenylpyridine depending on the reaction conditions. 1,4-Dihydropyridine 4 was the main product formed at 80 °C (76%), and 2-phenylpyridine 7 was the main product at 40 °C (91%), in oxidant-free conditions, using CeO2 catalyst. It is the first report that shows that, not only the temperature but also the nature of the catalyst may change the product selectivity in Hantzsch reactions. 相似文献
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Banda Gangadasu Srinivasan Palaniappan Chellachamy Anbalagan Amarnath Vaidya Jayathirtha Rao 《应用聚合物科学杂志》2006,102(2):1741-1745
Polyaniline salts were prepared by doping polyaniline base with different Bronsted acids (sulfuric, nitric, phosphoric, perchloric, hydrochloric acid) and organic acids (p‐toluene sulfonic acid, 5‐sulfosalicylic acid). Polyaniline complexes were also prepared using Lewis acids (aluminum chloride, ferric chloride). Polyaniline salts and polyaniline complexes were used as catalysts in Biginelli reaction for 5‐(methoxycarbonyl)‐6‐methyl‐4‐phenyl‐3,4‐dihydropyrimidin‐2(1H)‐one synthesis. Benzaldehyde and urea were reacted with methyl acetoacetate using polyaniline‐p‐toluene sulfonate salt as catalyst with different reaction time, temperature, and amount of catalyst. The use of polyaniline catalysts is feasible because of the easy preparation, easy handling, stability, easy recovery, simple work‐up procedure, reusability, excellent activity with less amount of catalyst, and eco‐friendly nature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1741–1745, 2006 相似文献
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《国际聚合物材料杂志》2012,61(9):891-903
A simple, one-step synthesis of 4-vinylpyridine polymer crosslinked with 2% divinylbenzene [poly(4vp-dvb)] anchored with ceria nanocrystals via in situ reactions that involve simultaneous formation of the polymer and ceria nanocrystals is presented. The polymer support is formed by free radical suspension polymerization of the monomers, while ceria nanocrystals are generated from CeCl3·7H2O by the homogeneous precipitation method in a single pot. The polymer supports were characterized by XRD, TEM, SEM, ESCA, and TGA and then tested for their ability as heterogeneous recyclable catalysts in a Biginelli reaction. The catalytic activities of these supports were found to be far superior to the two-step conventional one and simultaneous microporous bead counterparts. Reusability is an added advantage over the other regularly used cerium-based catalysts in aqueous media. The significant increase in the catalytic activity is due to the higher Ce/N ratio and predominance of well-defined and more reactive exposed planes of ceria nanocrystals on the new supports. Such catalysts are of great importance due to environmental, practical and economical concerns. 相似文献