脱铝超稳Y沸石负载杂多化合物催化剂的液相酯化性能

制备了一系列脱铝超稳Y沸石(DUSY)负载的12-磷钨杂多酸(PW)及其铯盐催化剂, 表征了其比表面和酸强度, 并在乙酸和正丁醇液相酯化反应中考察了催化剂的活性、选择性和稳定性. 结果表明, DUSY上引入PW后, 酯化反应的催化活性明显提高, 正丁醇的转化率从49.5%上升到86.4%, 而PW的这种促进作用并未在超稳Y沸石负载的PW催化剂上观察到; DUSY负载磷钨酸铯盐催化剂(Cs_2.5H_0.5PW/DUSY)的转化率高达94.6%, 且乙酸正丁酯的选择性为100%; 催化剂稳定性考察表明, 经过5次反复使用后, 负载磷钨酸铯盐的催化活性仍高达81.6%, 而相应的负载磷钨酸的催化活性却大幅度下降到47.6%; 催化剂溶脱性研究表明, 催化剂在反复使用过程中活性下降的量与活性组分在极性体系中的溶脱量成对应关系, 说明催化剂活性下降的主要原因是杂多酸(盐)活性组分的流失造成的, 而负载磷钨酸铯盐良好的催化稳定性来源于磷钨酸铯盐的难溶脱性.     

SiO2负载磷钨杂多酸催化的甲苯与乙酸酐酰化反应

以SiO2负载12-磷钨酸（PW）为催化剂,对甲苯与乙酸酐(AA)的酰化反应进行了研究。采用XRD、BET、TGA和NH3-TPD等对PW/SiO2催化剂进行了表征。结果表明,PW负载量及焙烧温度对PW/SiO2的酸性、PW在SiO2上的分散状态以及酰化催化活性有明显的影响。PW的负载量40%（按质量计）、焙烧温度300℃制备的PW(40%)/SiO2催化剂,其PW在载体表面的分散度好,酸量及酸强度适宜,对甲苯与乙酸酐的酰化反应具有较高的催化活性。在130℃,催化剂/乙酸酐（质量比）2.2时,催化反应效果最佳。     

固体酸催化合成蓖麻基癸二酸二辛酯的研究

以蠕虫(Worm-like)状介孔材料为载体,采用浸渍的方法将磷钨酸负载到介孔载体上制备不同磷钨酸负载量的固体酸催化剂.通过X射线衍射(XRD)、红外光谱(FT-IR)和N2吸附-脱附等表征手段对其物理化学性质进行分析,结果表明磷钨酸成功地负载于Wormlike介孔材料上.将一系列负载型磷钨酸催化剂用于癸二酸二辛酯的合成反应中,考察其酸催化活性,并对磷钨酸负载量、癸二酸和异辛醇物质的量比、反应温度以及反应时间等因素对酯化率的影响进行了研究.实验结果表明:当反应控制温度在120℃、癸二酸与异辛醇物质的量比为1∶3、反应时间为3h、磷钨酸负载量为50%时,反应酯化率可达98.2%.     

正庚烷在β沸石负载的磷钨杂多酸催化剂上加氢异构化

制备了系列含微量Pt（0．4％）的负载型磷钨杂多酸（PW）催化剂，采用Hβ或通过水热和盐酸联合脱铝的Hβ沸石作为催化剂载体，并在微型常压固定床催化反应器上考察了所制备的催化剂在正庚烷临氢异构化反应中的催化性能。结果表明，Pt及PW能够高度分散在催化剂载体表面；PW负载量及载体的水热处理温度和时间都显著影响催化剂的转化率和选择性，与未负载杂多酸的催化剂相比，负载杂多酸后的催化剂的正庚烷转化率有大幅度提高，异构化产物有所下降，但仍保持较高的异构化选择性。     

含双金属的DUSY负载磷钨酸催化剂上正庚烷 临氢异构化

用脱铝USY沸石(DUSY)负载12-磷钨酸(PW), 并以此为载体制备含Pt和Ce(或La)的双金属催化剂, 用XRD, BET, IR以及氢吸附等表征了催化剂的物化性质, 并在常压固定床反应器上考察催化剂的正庚烷临氢异构化反应性能. 结果表明, USY经过水蒸气和酸的联合处理并负载了PW和双金属以后仍能保持沸石原有结构, 同时催化剂中的PW保持了完好的Keggin结构, 金属助剂Ce的加入可以明显提高贵金属Pt的分散度; 在含Pt的催化剂中掺杂Ce或La, 特别是Ce后, 可显著提高催化剂的低温活性和异构化产物选择性. 催化剂的优化组成为 15CePt-PW/DUSY, 采用这一催化剂, 正庚烷异构化的优化反应条件为: 反应温度250℃, 液时空速1.4 h^-1, 在此条件下正庚烷的转化率为70.3%,异构化产物的选择性可达94.1%.     

高选择性和稳定性的CsPW/Nb2O5催化剂用于甘油脱水制备丙烯醛（英文）

以磷钨酸铯盐Cs2.5H0.5PW12O40(CsPW)为活性组分,负载到Nb2O5载体上,并用于甘油脱水制备丙烯醛的反应中.通过调节焙烧温度(400–700°C)以及活性组分负载量(5儃60 wt%),对催化剂酸性进行调节.CsPW负载量为20 wt%,500°C焙烧的CsPW/Nb2O5催化剂性能最佳,甘油转化率为96%,丙烯醛选择性为80%,反应10 h内没有失活现象,并且该催化剂具有良好的热稳定性,可通过烧炭进行再生.     

负载Fe3（CO）12催化剂的制备及合成氨的催化活性

以Ｆｅ_３（ＣＯ）_（１２）为母体，以活性氧化铝或活性炭为载体制备了负载型氨合成催化剂．在固定床管式流动反应系统中测定了催化活性，并与以Ｒｕ_３（ＣＯ）_（１２）和ＲｕＣｌ_３·ｘＨ_２Ｏ为母体的负载催化剂以及低温高活性氨合成工业催化剂的活性进行了对比。结果表明：以活性炭为载体的Ｆｅ_３（ＣＯ）_（１２）催化剂在１５ＭＰａ、４００℃以上表现出很高活性，且每克纯活性组分的催化活性在某些温度下比当前活性较高的工业熔铁催化剂的活性要高得多，但低温常压下几乎无活性。负载钉催化剂在低温常压下即显活性，且以ＲｕＣｌ_３·ｘＨ_２Ｏ为母体，比以Ｒｕ_３（ＣＯ）_（１２）为母体的负载钌催化剂活性高。     

磷钨酸“瓶中船”型催化剂的合成、表征及催化分解NOx性能

采用原位合成的方法 ,在微波辐射条件下制备了样品NH4PW-NaY,并通过FTIR、XRD、低温氮吸附-脱附等手段确认了该样品为磷钨酸铵(NH4PW)存在于NaY沸石超笼中的"瓶中船"型催化剂。通过NH4PW与NOx反应生成磷钨酸(HPW)的方式将NH4PW-NaY转化为HPW-NaY,并通过红外及红外吡啶吸附等表征手段证实了NaY沸石超笼中只含有磷钨酸的"瓶中船"型催化剂HPW-NaY被首次制备。随后研究了该催化剂对NOx的吸附-脱附性能,结果表明,在吸附温度为170℃时,HPW-NaY对浓度为1 696 mg.m-3的NOx吸附容量为2.38 mgNOx.gcat-1,在通水蒸汽条件下,催化剂温度降至100℃时所吸附的NOx发生脱附,脱附后的催化剂可重复使用。最后通过程序升温脱附-质谱(TPD-MS)研究了HPW-NaY对NOx的催化分解性能,结果发现NOx在以NaY沸石为载体的HPW上的分解过程中有O2产生,且氧的产生滞后于N2O及N2,HPW-NaY催化分解NOx的转化率及N2选择性分别为61%与75%,均高于单纯HPW催化剂。     

活性炭负载磷钨酸催化剂的表征及其催化性能

研究了活性炭负载磷钨酸催化剂的表征及在丁基多苷合成中的催化性能.活性炭负载磷钨酸催化剂采用浸渍法制备,并用FT-IR光谱、XRD光谱、SEM等手段进行了表征.结果表明,磷钨酸负载到活性炭后保持了原有的Keggin结构,它在载体上的吸附过程可以分为单分子吸附、多分子吸附和体相堆积三个阶段.在丁基多苷合成反应中,催化剂负载量、磷钨酸溶脱量、葡萄糖转化率之间有较复杂的关系.杂多酸溶脱量随负载量增大而增大,转化率与杂多酸溶脱量之间没有直接联系.催化剂负载量在5%到60%之间变化时,控制催化活性的主要因素分别是催化剂酸量、比表面积、游离的杂多酸量.最佳负载量为20%.     

铈钛混合氧化物负载磷钨酸吸附-分解NOx性能

通过软化学途径合成了铈钛混合氧化物(CeO2-TiO2)载体材料,并分别通过等体积浸渍法和机械研磨法负载磷钨酸(H3PW12O40)。采用FTIR、XRD、SEM和BET比表面积测定对CeO2-TiO2及负载型多酸催化剂进行了表征;考察了负载量、负载方法、吸附温度等因素对催化剂吸附NOx效率的影响;选取吸附性能最佳的催化剂进行了NOx催化分解实验,探讨了NOx吸附-分解机理。结果表明:相对于等体积浸渍法,机械研磨法更适合此类载体负载H3PW12O40,其NOx吸附效率均高于H3PW12O40及载体本身;在0~60%的负载量范围内,随着H3PW12O40负载量的增加,负载型催化剂吸附NOx的效率呈先升后降趋势,负载量为40%时NOx吸附效率最佳,达90%;吸附过程中NOx与催化剂活性组分H3PW12O40发生作用,生成NOH+;H3PW12O40二级结构中结晶水对催化剂吸附NOx有重要作用;当温度从150℃升至450℃时,被吸附的NOx发生分解,分解产物的组成与N2的收率均受升温速率的影响,升温速率越快,N2收率越高。向吸附分解NOx后的催化剂床层通入含有水蒸气的空气,可有效补充NOx分解过程中H3PW12O40失去的结晶水,从而恢复催化剂优良的NOx吸附分解性能,实现催化剂的有效再生利用。     

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.     

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.     

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

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.