高分子载体Lewis酸催化剂:苯乙烯、丙烯腈共聚物-四氯化钛复合物

高分子催化剂是功能性高分子的重要组成部分,是目前催化剂研究的方向之一,近年来发展很快。我们曾将在空气中强烈水解的Lewis酸四氯化钛与聚苯乙烯反应制备了一种比较稳定的复合物,它对酯化、缩醛、缩酮等有机反应具有良好的催化效能,也可作为α-甲基苯乙烯正离子聚合的有效催化剂,在室温下即可获得高分子量的聚合物。为了进一步改进其稳定性和重复使用性能,本文合成了一种苯乙烯与丙烯脂的共聚交联小球,然后与四氯化钦反应制成了一种更加稳定的高分子载体Lewis酸催化剂,它不但对醋化、缩醛、缩酮等有机反应有很高的催化活性,而且重复使用性能大为改善,是一种很有希望应用于实际的高分子催化剂。     

以高分子为载体的Lewis酸催化剂——苯乙烯、甲基丙烯酸甲酯共聚物-四氯化钛复合物的制备及其在有机合成中的应用

均相催化剂的固载化和以高分子材料作为催化剂载体的研究及开发,近年来受到人们的的重视。Neckers和Sket等曾将极易水解的AlCl_3和BF_3分别与聚苯乙烯反应制成高分子载体催化剂,应用于缩醛、缩酮、酯化等反应,具有良好的催化效能。本文将在空气中极易水解的Lewis酸四氯化钛与苯乙烯和甲基丙烯酸甲酯的共聚物小球反应,制成了一种十分稳定的高分子载体Lewis酸催化剂,证明它对酯化、缩醛、缩酮等反应有较高的催化活性,并可重复使用、回收再生。由于它制备简单、操作方便、易于从反应体系中分离、无污染,因此具有良好的应用前景。     

硅胶固载化—（Lewis）酸催化剂的研究：Ⅰ.硅胶固载化—四氯化钛复合物催…

以硅胶球为基质键合ｒ－ＧＯＰＳ并各接枝上具有络合功能的三种配件，邻位氨基吡啶、间酰氨基吡啶及对酰氨基吡啶，再和ＴｉＣｌ４络合成固载化的Ｌｅｗｉｓ酸催化剂，将这些催化剂进行缩醛、缩酮及酯化反应，有很好的催化活性，重复使用多次不失效。本文在合成此类催化剂的过程中利用热失重（ＴＧ）法及等离子光谱法（ＩＣＰ）等检测方法对合成此类催化剂的第一步进行跟踪检测，得到键合反应，开环反应及络合反应过程中的键合量，开     

钨硅酸的制备及其在催化合成缩酮(醛)中的应用

本文探讨了钨硅酸的制备方法,以合成环己酮1,2-内二醇缩酮为例验证钨硅酸的催化活性,并探讨了合成其它缩酮（醛）的适宜条件,得到的收率分别为：环己酮1,2-丙二醇缩酮85．5％、环己酮乙二醇缩酮89．6％、丁酮乙二醇缩酮79．5％、丁醛乙二醇缩醛89．1％、丁醛1,2丙二醇缩醛81．5％。     

高分子固载化Lewis酸催化剂——聚苯乙烯-三氯化铝/四氯化钛复合物

<正> 均相催化剂的固载化是目前催化剂研究方向之一。Skct等首次将BF_5和AlCl_3分别与苯乙烯反应制成高分子催化剂,对酯化、缩醛、缩酮等有机反应具有良好的催化作用。我们曾将四氯化钛与聚苯乙烯反应制成一种稳定复合物,有良好的催化效能。为了改进其重复使用性能,本文将等摩尔的AlCl_3,和TiCl_4的Lewis酸同时与聚苯乙烯交     

高岭土负载SO42-/ZrO2-TiO2催化剂的制备及其在缩酮合成中的应用

以经H2SO4处理焙烧的高岭土为载体,制备了以其负载的SO2-4/ZrO2-TiO2固体酸催化剂。 用FT-IR、XRD和NH3-TPD等测试技术表征了催化剂的微观结构及酸强度,考察了对环己酮乙二醇缩酮反应的催化活性及稳定性。 结果表明,酸化处理使高岭土表面酸量增加,但酸强度变化不大,而其负载SO2-4/ZrO2-TiO2后,经500 ℃焙烧3 h其酸量及酸强度显著升高。 环己酮用量为0.2 mol、乙二醇0.24 mol、催化剂1.2 g、带水剂环己烷15 mL,回流反应70 min后,缩酮收率可达96.8%,催化剂重复使用5次收率保持在90%以上。     

固体酸催化合成邻苯二甲酸二戊酯的研究

以苯酐和正戊醇为原料,采用自制的固体酸SO4^2-／SiO2、SO4^2-／Fe2O3、SO4^2-／SnO2及SO4^2-／TiO2作为催化剂合成邻苯二甲酸二戊酯（DAP）,分别考察固体酸催化剂的种类、固体酸催化剂的用量、醇酐比、反应时间等因素对合成DAP产率的影响。实验结果表明,其优化的工艺操作条件为：苯酐0．1mol,固体酸催化剂SO4^2-／SiO2 1．7g,醇酐比2．4：1,带水剂二甲苯20mL,反应时间3．5h,其产品收率达91．3％以上。SO4^2-／SnO2作为该反应的催化剂具有催化活性高、寿命长、可多次重复使用、产物易纯化分离且产品色泽浅等优点,可望代替传统的浓硫酸作催化剂应用于DAP的合成。     

高岭土负载SO2-4/ZrO2-TiO2催化剂的制备及其在缩酮合成中的应用

以经H2SO4处理焙烧的高岭土为载体,制备了以其负载的SO4(2-)/ZrO2-TiO2固体酸催化剂.用FT-IR、XRD和NH3-TPD等测试技术表征了催化剂的微观结构及酸强度,考察了对环己酮乙二醇缩酮反应的催化活性及稳定性.结果表明,酸化处理使高岭土表面酸量增加,但酸强度变化不大,而其负载SO4(2-)/ZrO2-TiO2后,经500℃焙烧3 h其酸量及酸强度显著升高.环己酮用量为0.2 mol、乙二醇0.24 mol、催化剂1.2 g、带水剂环己烷15 mL,回流反应70 min后,缩酮收率可达96.8%,催化剂重复使用5次收率保持在90%以上.     

碘掺杂聚苯胺催化合成环己酮1,2-丙二醇缩酮

合成了聚苯胺-碘(PAn-I2)催化剂,并对其结构进行了表征。并通过环己酮与1,2-丙二醇合成环己酮1,2-丙二醇缩酮,探讨了PAn-I2对缩酮反应的催化活性。实验结果表明,PAn-I2是缩酮反应的良好催化剂,在环己酮100 mmol,n(环己酮)∶n(1,2-丙二醇)=1∶1.5,催化剂用量为反应物总质量的3%,环己烷12 mL,反应时间2 h的优化条件下,环己酮1,2-丙二醇缩酮的收率可达92.1%。     

以高分子为载体的Lewis酸催化剂: 苯乙烯、甲基丙烯酸甲酯共聚物-四氯化钛复合物的制备及其在有机合成中的应用

本文将在空气中极易水解的Lewis酸四氯化钛与苯乙烯和甲基丙烯酸甲酯的共聚物小球反应, 制成了一种十分稳定的高分子载体Lewis酸催化剂, 证明它对酯化,缩醛, 缩酮等反应有较高的催化活性, 并可重复使用, 回收再生. 由于它制备简单, 操作方便, 易于从反应体系中分离、无污染, 因此具有良好的应用前景.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

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.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.