钙基负载型固体碱催化酯交换反应活性评价

动植物油脂与醇通过酯交换反应制备生物柴油,目前,工业上一般采用NaOH、KOH、NaOCH,等均相催化剂。均相催化剂的缺点是产品后处理复杂,产生大量含碱含油工业废水。而非均相固体碱催化酯交换反应,产品与催化剂分离容易,产品不需要水洗,避免了大量废液的排放。采用非均相固体碱制备生物柴油的文献报道较多,但固体碱的碱中心数、碱中心强度对酯交换反应影响的报道较少。本研究制备了钙基负载型固体碱催化剂,重点研究钙基负载型固体碱的制备工艺条件对碱强度、碱量分布的影响,考察碱强度、碱量分布对催化菜籽油与甲醇的酯交换反应制备生物柴油转化率的影响。     

催化裂化汽油固体碱预碱洗的研究──负载固体碱对硫化氢的吸附过程分析

以活性炭为载体,碱金属化合物为活性组分,制备出负载固体碱,对其吸附硫化氢性能进行了研究。结果表明,此类固体碱吸附硫化氢能力较强,在固体碱孔外主要进行化学吸附,在固体碱孔内以物理吸附为主,化学吸附和物理吸附能力分别与固体碱、固体碱孔内所负载活性组分的量有关     

催化裂化汽油固体碱预碱洗的研究：负载固体碱对硫化氢的吸附过？…

以活性炭为载体,碱金属化合物为活性组分,制备出负载固体碱,对其吸附硫化氢性能进行了研究。结果表明,此类固体碱吸附硫化氢能力较强,在固体碱孔外主要进行化学吸附,在固体碱孔内以物理吸附为主,化学吸附和物理吸附能力分别与固体碱、固体碱孔内所负载活性组分的量有关。     

金属氧化物固体碱在有机合成中的应用

综述了近年来金属氧化物固体碱的研究现状,包括金属氧化物固体碱的种类及其在有机合成中的应用进展,并对固体碱催化剂的未来发展方向进行了展望.     

二甲胺乙基膦酸钡新型固体碱催化剂的研究

首次用二甲胺乙基膦酸与氯化钡在碱性溶液中制得二甲脘乙基膦酸钡载体,用５％ＮａＯＨ溶液处理该载体,制得相应的固体碱,并用元素分析,ＩＲ、ＴＧ、ＤＴＡ、ＤＴＧ对其进行了表征,用指示剂法,测得固体碱碱强度（Ｈ－）为９．３～１５．０;采用苯甲酸滴定法,测定了载体２和固体碱３在水中的游离碱量;讨论了载体制备中,驾流时间对载体２和固体碱３在水中游离碱量的影响。将固体碱用于催化Ｋｏｎｅｖｅｎａｇｅｌ缩合反应,产     

固体碱催化剂

综述了最近30年来固体碱催化剂的研究现状，包括固体碱催化剂的种类、优缺点以及各类催化剂中影响其催化性能的因素。重点探讨了碱性前驱体和载体对负载型无机固化碱碱强度的影响，展望了未来固体碱剂的发展方向。     

新型介孔固体碱材料的合成*

介孔固体碱能够催化各式各样的化学反应,降低生产成本并减少对环境的污染,可望代替液体碱成为新一代环境友好催化材料。介孔材料的飞速发展为介孔固体碱的研制提供了契机,到目前为止,研究人员已经采用不同途径合成出了多种类型的介孔固体碱材料。本文以主体材料作为线索,综述了在介孔氧化硅、介孔氧化铝、介孔氧化锆和介孔炭上产生碱性位的方法,描述了所制得固体碱的结构、性质及其在催化反应中的应用。在此基础上,评价了这些制备方法的优缺点,剖析了碱性位产生机理,并对介孔固体碱的发展前景进行了展望。     

过渡金属改性Mg-Al基固体碱催化剂上碳酸丙烯酯与甲醇合成碳酸二甲酯的研究

以共沉淀法制备了一系列不同价态过渡金属(Fe、Cu、Zr)改性的Mg-Al固体碱催化剂,考察了其对于甲醇与碳酸丙烯酯(PC)酯交换合成碳酸二甲酯的反应性能。采用XRD、N_2吸附-脱附、FT-IR、XPS、CO_2-TPD等手段对催化剂的物理化学性质进行了表征。结果表明,催化剂的碱强度、碱密度是影响催化活性的主要因素,不同价态过渡金属的加入可以调控Mg-Al固体催化剂的碱性。在考察的催化剂中,FeMgAl催化剂具有最高的表面碱密度,因此,表现出最好的催化性能。在温度为65℃、时间为4 h、甲醇与PC物质的量比为10∶1、催化剂用量为4%的反应条件下,PC转化率可达66.2%。     

金属基介孔固体碱催化剂的制备与应用

应可持续发展与绿色化学的需要,非均相催化剂替代传统的均相催化剂引起研究者的广泛重视。其中,金属基介孔固体碱具有比表面积大、腐蚀性小、传质速率快、易分离等优点,是一种理想的绿色催化剂。本文综述了近年来制备不同的金属基介孔固体碱(包括MgO、类水滑石(HTs)及改性的Al₂O₃、ZrO₂、CeO₂)的研究进展,重点讨论了软模板法、硬模板法、溶剂挥发自组装法、无模板剂法等制备各种金属基介孔固体碱的方法和机理。此外,还介绍了金属基介孔氧化物在催化、储能与环境领域中的实际应用。最后,简要分析了金属基介孔固体碱制备过程中存在的问题,并展望其在未来的发展趋势,为新型金属基介孔固体碱的构筑提供了新的思路。     

吸附量热技术和金属氧化物催化剂的表面酸碱性

 探讨了吸附量热技术及其在测定固体表面酸碱性中的应用．使用NH3和CO2为探针分子,吸附量热技术能够定量地描述固体表面酸碱中心的数目和强度分布．结合原位红外光谱,还能够详细地了解表面酸碱中心的性质：金属氧化物表面的Lewis酸中心和碱中心分别是表面配位不饱和的金属离子和氧负离子,Brnsted酸中心和碱中心则是金属氧化物表面的羟基．通过测量吸附热,金属氧化物的表面酸碱性强度可与Sanderson电负性关联起来,也可以考虑使用Drago参数来描述固体表面的酸碱性．根据酸碱性与电负性的关系以及对表面配位不饱和离子的要求,有可能通过选择合适的复合金属氧化物组成,获得具有一定酸（碱）量和酸（碱）强度的固体酸（碱）．     

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.     

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.     

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.     

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.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

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%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

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.