羟基铝柱撑二硫化钼的制备及其催化加氢性能

 采用单分子层技术将羟基铝聚合物Al7+13阳离子嵌入到二硫化钼板层间,得到层间距为1.488～1.599 nm的柱撑复合材料. X射线粉末衍射等研究表明,羟基铝聚合物Al7+13经60 ℃恒温陈化2 d即可作为稳定的柱撑液使用; 在柱撑反应体系中,较小的Al/Mo摩尔比有利于获得客体物种较均一和结晶度较好的柱撑复合材料. 与原料 2H-MoS2 相比,柱撑二硫化钼的层间距增大,晶粒变小,比表面积增加. 差示扫描量热分析结果表明,柱撑材料具有较好的热稳定性. 选择苯饱和加氢反应为探针,测定了柱撑材料的催化活性. 气相色谱测定结果表明,柱撑二硫化钼的催化性能显著优于未柱撑的 2H-MoS2 和Raney Ni催化剂. 这与柱撑材料比表面积的增大、可能存在的缺陷增多而导致活性位增多以及对氢气的有效吸附增加有关.     

铝柱撑二硫化钼的制备及其催化氧化性质

本文采用单分子层技术将聚合羟基铝簇离子嵌入到二硫化钼板层间，得到层间距为1.481至1.519 nm的柱撑二硫化钼复合材料。XRD、DSC等研究表明，柱化液的滴加浓度越稀、柱撑反应体系中Al∶MoS₂物质的量之比越小越有利于获得层间距较大的柱撑材料。与原料2H-MoS₂相比，柱撑材料的层间距增大，颗粒度变小，比表面积增加。在氧气条件下，对Na₂S的催化氧化实验表明，柱撑材料较原料2H-MoS₂的催化氧化活性提高3～4倍，且光催化活性大于催化活性。这与柱撑材料的比表面积增加所导致催化活性部位的增多，以及光致电子-空穴对的产生有关。     

介孔锆柱撑钛酸盐材料的制备、表征及光催化性能

采用单分子层剥离-重堆积技术将聚合羟基锆离子嵌入到钛酸盐板层间,制得层间距为1.92~2.01nm的介孔钛酸盐柱撑复合材料。X-射线衍射(XRD)、热重-示差扫描热分析(TG-DSC)、扫描/透射电镜(SEM/HR-TEM)和N2吸附等手段对材料物化性质进行了分析。结果表明,客体锆离子主要以[Zr4(OH)16-n(H2O)8+n]n+(记为Zr4)的形式存在于主体层间域中,且柱撑体系中nZr/nTi比越小,越有利于获得层间距和比表面积较大的柱撑材料。紫外光降解亚甲基蓝实验表明,柱撑材料对亚甲基蓝降解率为钛酸盐主体的3.5倍,这与柱撑形成的介孔结构以及主客体间的电子耦合有关;350℃热处理后材料对亚甲基蓝的降解率进一步提高,说明主客体间形成了更有效的欧姆接触。     

铁掺杂羟基锆柱撑钛酸盐的制备及光催化性能

采用单分子层剥离-重堆积技术将掺铁的聚合羟基锆离子嵌入到钛酸盐层间, 制得了铁掺杂羟基锆柱撑钛酸盐复合材料(FZPT), 考察了Fe掺杂对Zr柱撑钛酸盐复合材料(ZPT)形成及光催化活性的影响. 利用X射线衍射仪(XRD)、 扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 紫外-可见漫反射光谱仪(UV-Vis DRS)和吸附分析仪等对材料进行了表征. 结果表明, 当铁的掺入量小于锆质量的10%时, 复合柱撑材料FZPT的孔径和比表面积随着Fe掺入量的增加而增大, 继续增加则结果相反. 紫外-可见光催化降解亚甲基蓝(MB)实验结果表明, FZPT催化活性均高于ZPT, 可能与掺杂后材料形成介孔结构与比表面积增大有关. 样品FZPT-0.20的可见光催化活性相对较好, 表明材料的光催化活性与掺杂后柱撑材料中含铁客体与主体间的电子耦合作用有关.     

Fe-Al 柱撑膨润土的制备及其非均相Fenton降解橙黄II

通过离子交换方法制备不同Fe含量的Fe-Al柱撑膨润土,并且研究了其作为非均相Fenton催化剂降解橙黄II的性能.通过X射线粉末衍射(XRD),比表面积(SBET),傅里叶变换红外(FTIR)光谱,拉曼(Raman)光谱和扫描电子显微镜(SEM)研究其结构特征.结果显示,钠化膨润土的层间距为1.24 nm,经过柱撑之后,Al柱撑膨润土的层间距增大到1.77 nm,Fe-Al柱撑膨润土为1.72 nm左右,并且比表面积也有明显增大.XRD和Raman结果表明Fe/(Fe+Al)摩尔比达到20%时,样品中出现α-Fe2O3,膨润土未能形成柱撑.在橙黄II初始浓度为100 mg L-1,催化剂用量为1.0 g L-1,温度为40°C,pH为3.0,H2O2初始浓度为10 mmol L-1的条件下,考察了柱撑膨润土的Fenton催化活性.结果表明,Fe-Al柱撑膨润土的催化性能随着Fe含量的增多先增大后略有降低,当Fe/(Fe+Al)摩尔比为10%时达到最大,橙黄II溶液在4 h内色度去除率和化学需氧量(CODCr)去除率分别达到100%和87.73%,并且降解反应为非均相Fenton反应.研究了Fe-Al柱撑膨润土的重复使用性.催化剂循环使用4次,仍然具有良好的活性.     

杂多阴离子柱撑水滑石的合成、热稳定性、酸碱性研究

采用水溶液中阴离子直接交换法合成了过渡金属单取代Keggin结构杂多阴离子SiW11M(H2O)O39^6^- (M=Mn^2^+, Fe^2^+, Co^2^+, Ni^2^+, Cu^2^+,Zn^2^+)柱撑水滑石。用元素分析、XRD和IR对产物的组成与结构进行了表征。XRD结果给出柱撑产物的底面间距达1.47nm。DTA结合不同温度下焙烧样品的XRD、IR研究表明, 柱撑水滑石在低于250℃时脱除物理吸附水和层间水; 在400~500℃之间脱除层上羟基, 形成一个无定形的混合氧化物状态; 在600℃以上无定形态结晶为晶态氧化物混合物。异丙醇探针反应表明, 柱撑水滑石具有高于水滑石前驱体和相应杂多酸盐的催化活性, 且同时存在酸碱两类催化活性中心, 但酸中心明显较强。     

氧化铬柱层状三氧化钼的合成

采用醋酸铬[Cr(OAc)~3]水溶液与具有层状结构的钼青铜{[Na(H~2O)~5]~0~.~2~5MoO~3]进行离子交换瓜制得铬齐聚体柱撑的层状氧化钼化合物。经350℃焙烧后,首次得到了多孔高比表面积的氧化铬柱层状氧化钼材料。通过XRD,TEM,DTA和BET测试手段对其进行了表征,并考察了350℃时不同的焙烧气氛对产物层间距和表面积等的影响。结果表明,在不同气氛中焙烧,产物层间距相同(1.092nm),但比表面积有很大的变化,其中,在含4%(体积分数)氧气的氮氧混合气中焙烧,获得的样品比表面积(BET)最大,达82.4m^2·g^-^1,平均孔径为6.42nm。     

氧化铬柱层状三氧化钼的合成

采用醋酸铬[Cr(OAc)~3]水溶液与具有层状结构的钼青铜{[Na(H~2O)~5]~0~.~2~5MoO~3]进行离子交换瓜制得铬齐聚体柱撑的层状氧化钼化合物。经350℃焙烧后,首次得到了多孔高比表面积的氧化铬柱层状氧化钼材料。通过XRD,TEM,DTA和BET测试手段对其进行了表征,并考察了350℃时不同的焙烧气氛对产物层间距和表面积等的影响。结果表明,在不同气氛中焙烧,产物层间距相同(1.092nm),但比表面积有很大的变化,其中,在含4%(体积分数)氧气的氮氧混合气中焙烧,获得的样品比表面积(BET)最大,达82.4m^2·g^-^1,平均孔径为6.42nm。     

羟基铁柱撑蒙脱土-δ-MnO_2复合体Fenton催化降解亚甲基蓝

制备了一系列羟基铁柱撑蒙脱土-δ-MnO2复合材料,采用X射线粉末衍射(XRD)、比表面积(SBET)及扫描电子显微镜(SEM)研究其结构特征。结果显示:钙基蒙脱土的层间距为1.47 nm,经过柱撑之后,羟基铁撑蒙脱土的层间距增大到1.51 nm,羟基铁柱撑蒙脱土-δ-MnO2复合体为1.55 nm左右,并且比表面积较原土也有明显的增大。以亚甲基蓝为目标污染物,研究了其作为异相催化剂的催化性能,考察了溶液H2O2加入量、δ-MnO2含量及p H值等对亚甲基蓝降解性能的影响。结果表明,在实验条件下,催化剂的催化活性随H2O2浓度的增加而升高,当nFe/nMn=0.241时,催化活性最好,且有较大的p H适用范围。亚甲基蓝的异相催化降解过程符合准一级动力学方程。催化剂循环使用3次,仍然具有良好的活性。     

混合金属络合物羟基铬铝交联蒙托土的合成

用取代法和共聚法合成了不向Cr/Al比的混合金属络合物羟基铬铝交联蒙托土,用XRD、DTA考察了其热稳定性,用~(27)Al-NMR、UV、ESR等技术对柱化溶液中铬和铝的状态进行了研究。结果表明,两种方法均合成出结构相近且底面间距d(001)为1.90～2.49nm的羟基铬铝交联蒙托土。发现Cr/Al比对羟基铬铝聚合物的结构、d(001)值、比表面热稳定性均有较大影响;随Cr/Al比的增加,d(001)逐渐增加,热稳定性下降,但在惰性气氛下热稳定性较好(>500℃)。     

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.