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1.
利用Benson基团贡献法计算了乙烯齐聚制α-烯烃反应各物质的标准摩尔生成焓、标准摩尔熵和摩尔定压热容,在298~700 K温度范围内对乙烯齐聚制α-烯烃反应体系的反应热、吉布斯自由能以及反应平衡常数进行了详尽的计算,分析了不同反应步骤的热力学平衡与限度,对不同反应发生的热力学可能性与顺序进行了判断,考察了反应温度和压力对乙烯齐聚制α-烯烃反应化学平衡的影响,确定了乙烯齐聚制α-烯烃反应体系适宜的工艺条件.结果表明:乙烯齐聚制α-烯烃反应为放热反应;从热力学上看,温度低于546 K时,乙烯齐聚生成直链α-烯烃反应为自发过程,且比α-烯烃异构化和烯烃歧化反应更容易进行;低温、高压有利于乙烯齐聚制α-烯烃反应的进行;乙烯齐聚制α-烯烃反应体系适宜的工艺条件为温度323~473 K,压力5~20 MPa,且在SHOP法的工艺条件下(温度363 K,压力10.3 MPa),乙烯齐聚生成直链α-烯烃反应的热力学平衡转化率接近于100%. 相似文献
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乙烯线性齐聚的研究(Ⅳ)——ⅣB族化合物催化乙烯齐聚中的几个问题 总被引:1,自引:0,他引:1
直链低碳α-烯烃(指十碳以下的正构α-烯烃)是重要的基本化工原料,广泛用于合成润滑油、增塑剂、精细化工产品及共聚单体.以过渡金属络合物催化乙烯齐聚获得直链α-烯烃被认为是当前最先进的方法.镍络合物体系催化乙烯齐聚得到α-烯烃的SHOP法是Ⅷ族金属络合物催化反应的代表.它是以得到高碳α-烯烃为目的.以ⅣB族金属络合物为基础的体系主要催化烯烃高聚,催化齐聚的研究工作尚少.近年来曾有锆酸酯和烷基铝催化乙烯齐聚的报导,其C_4-C_8烯烃的收率最高可达92%.本文将报导用简单易得的锆盐和烷基铝为基础组成的体系催化乙烯齐聚的结果,及对此类催化体系的失活问题进行探讨. 相似文献
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乙烯线性齐聚的研究Ⅱ、ZrCl4—Et2AlCl二组分体系的催化作用 总被引:1,自引:1,他引:1
1.引言 随着石油化工和精细化工的日益发展,工业上对直链α-烯烃的需要愈来愈迫切。乙烯齐聚反应是制备直链α-烯烃的重要方法。以过渡金属锆的化合物与烷基铝化合物组成的二元Ziegler-Natta体系催化乙烯线性齐聚,其文献和专利报导较少,且以合成高碳α-烯烃为目的。我们曾报导过ZrCl_4-Et_3A1_2Cl_3体系催化乙烯齐聚,虽能得到低碳α-烯烃,但效果较差。在使用Et_2AlCl作活化剂时结果较好。 相似文献
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制备了硅胶负载型2,6-二亚胺基吡啶铁系齐聚催化剂。考察了不同负载温度,聚合中乙烯加压方式,催化剂的加入量以及丙烯对乙烯齐聚活性和α-烯烃分布的影响。结果表明,低温负载有利于催化剂活性提高,分段加压可以使催化剂的活性周期增加,聚合温度平稳,单位助催化剂MAO转化的乙烯量增加,而α-烯烃的选择性基本不变。Fe催化剂负载后,以单位助催化剂MAO计算的乙烯转化率提高。增加催化剂的量后,单位助催化剂MAO转化的乙烯量增加。在乙烯齐聚中加入少量丙烯催化剂的活性降低,α-烯烃分布向低碳方向移动。 相似文献
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乙烯齐聚催化剂研究进展 总被引:2,自引:0,他引:2
综述了乙烯齐聚催化剂的研究进展.按照碳链的原子数目,简要介绍了α-烯烃的用途.按照后过渡金属催化剂和前过渡金属催化剂分类介绍了乙烯齐聚催化剂的研究情况,并重点介绍了乙烯三聚催化剂的研究进展,给出了部分聚合机理.文章最后介绍了α-烯烃除用乙烯齐聚催化剂方法外,还有石蜡热裂解、烷烃催化裂解、烷烃脱氢、烯烃二聚和歧化等方法制备.乙烯齐聚法所得产品线性化程度高,聚合度分布窄,分离费用低,产品质量好.在我国,石蜡裂解法为主要生产方法,因此在我国开展乙烯齐聚的研究,开发具有自主知识产权的齐聚催化剂,具有十分重要的意义. 相似文献
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多相催化乙烯齐聚制α-烯烃的研究(Ⅰ) 总被引:4,自引:0,他引:4
以金属离子交换型中孔分子筛MZSM-5、MZSM-5P为催化剂,在中压条件下对多相催化乙烯齐聚反应进行了探索性研究.结果表明,系列催化剂对乙烯的反应活性较NaZSM-5有显著的提高,但对目标产物α-烯烃的选择性差.对MZSM-5经表面修饰后的系列催化剂MZSM-5P,反应活性降低,而目标产物α-烯烃的选择性有所提高.这说明采用适宜的有机碱对离子交换型分子筛催化剂MZSM-5进行表面修饰是提高离子交换型分子筛催化剂乙烯齐聚反应选择性的一个有效方法. 相似文献
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为了制备聚丙烯/蒙脱土纳米复合材料,将Brookhart型的乙烯齐聚催化剂负载于有机蒙脱土片层间,进一步与丙烯聚合茂金属催化剂进行复配得到双功能催化体系。采用这种双功能催化剂体系通过催化乙烯齐聚得到α-烯烃/蒙脱土的齐聚产物,进一步将丙烯与这种齐聚产物共聚,合成了一系列结构不同的聚丙烯/蒙脱土纳米复合材料。通过气相色谱、X射线衍射(XRD)分析得出蒙脱土负载的铁系催化剂催化乙烯齐聚产物是以C_4~C_(16)为主的α-烯烃,蒙脱土以片层形式分散于齐聚产物的甲苯溶液中。研究了蒙脱土负载的铁系催化剂与共聚催化剂复配催化乙烯齐聚以及丙烯与齐聚产物共聚合的情况。通过XRD、透射电镜、差示量热分析、凝胶渗透色谱分析表征可知,蒙脱土以纳米片层剥离的形式均匀分散于聚丙烯基体中,聚丙烯/复合材料的结晶温度比纯聚丙烯有所下降,所得聚丙烯基体分子量在8.1×10~4~17.1×10~4g/mo L。 相似文献
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Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives. 相似文献
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The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion. 相似文献
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N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%). 相似文献
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Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones. 相似文献
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In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates. 相似文献
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An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions. 相似文献
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Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described. 相似文献
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用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在. 相似文献
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An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction. 相似文献
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The Diels-Alder reactivity of 1,2-heteroborines (H4C4B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed. 相似文献