以EDTANa2为矿化剂近中性条件下室温合成介孔二氧化硅

利用EDTANa2作为矿化剂, 在近中性条件下于室温合成了厚壁(约3 nm)蠕虫介孔分子筛. 在反应物配比为n(CTAB):n(TEOS):n(EDTANa2):n(H2O)=(0.05~0.2):(0.1~2):(0.1~0.5):(100~500)范围内都能得到介孔二氧化硅. 以XRD、N2吸附、FTIR、SEM和TEM详细考察了体系配比和温度对介孔二氧化硅结构和形貌的影响, 发现CTAB用量越大, 介孔d值相应增大. 温度对介孔二氧化硅的结构和形貌有很大的影响, 温度在2~15 ℃范围内都能生成孔径分布较规则的介孔, 介孔材料的形貌随温度的升高由空心管变成小颗粒聚集体; 合成的介孔分子筛中的模板剂可以通过乙醇萃取的方式除去. 提出了介孔的生成遵从(S+-E-)0-I0中性模板机理.     

W掺杂SiO2介孔材料的制备与表征

以非离子表面活性剂三嵌段共聚物P123为模板剂、正硅酸乙酯(TEOS)为硅源、钨酸钠(Na2WO4·2H2O)为钨源, 通过水热法一步合成了W掺杂的二氧化硅介孔材料W-SiO2, 并通过XRD、HRTEM、EDX、FT-IR、N2吸附-脱附等表征手段, 考察了随着W含量增加, W-SiO2介孔材料结构的变化规律以及钨物种在材料中的存在状态. 结果表明, 当WO3含量w(WO3)约为10%时, W-SiO2中的钨物种是高度分散进入介孔骨架,形成W-O-Si 键; 当w(WO3)=20%时, 样品中开始有未掺入到SiO2骨架中WO3的结晶出现; 当w(WO3)约60%时, W-SiO2 样品能保持很好的介孔孔道结构, 更高含量WO3掺入将破坏二氧化硅介孔结构.     

氨基桥联有机硅对Ag+的吸附性能及传质机理研究

利用二-(3-三甲氧基硅基丙基)胺(BTSPA)和正硅酸乙酯(TEOS)共聚,合成了一系列氨基桥联有机硅新型吸附材料。TEOS的加入提高了有机硅网络结构的刚性,有效避免了其孔结构的坍塌。N_2吸附和TEM测试结果表明,与以BTSPA为单一硅源前驱体相比,BTSPA和TEOS共聚制备的桥联有机硅吸附剂具有典型的介孔结构,其比表面积和孔体积均显著增大。吸附实验结果表明,共聚合成的氨基桥联有机硅材料对Ag~+表现出优异的吸附能力,静态平衡吸附量高达92.05mg/g。此外,吸附等温线符合Freundlich模型,吸附过程遵循拟二级动力学模型,粒内扩散是吸附限速步骤。本研究制备的氨基桥联有机硅作为高效选择性吸附剂在重金属废水处理中表现出良好的应用前景。     

Tb(DBM)3phen/APTES-SBA-15介孔复合体系的制备与表征

以三嵌段化合物P123为模板剂、正硅酸乙酯(TEOS)为无机硅源合成了有序介孔分子筛SBA-15. 选择Tb(DBM)₃phen为客体, 纳米级介孔分子筛为主体, 在氯仿中进行分子组装, 制备具有强发光性能的超分子纳米复合材料Tb(DBM)₃phen/APTES-SBA-15. 采用XRD, HRTEM, N₂吸附/脱附, FTIR和荧光光谱分析等对复合材料的结构与性能进行了研究.     

Tb(DBM)3phen/APTES-SBA-15介孔复合体系的制备与表征

以三嵌段化合物P123为模板剂、正硅酸乙酯(TEOS)为无机硅源合成了有序介孔分子筛SBA-15. 选择Tb(DBM)₃phen为客体, 纳米级介孔分子筛为主体, 在氯仿中进行分子组装, 制备具有强发光性能的超分子纳米复合材料Tb(DBM)₃phen/APTES-SBA-15. 采用XRD, HRTEM, N₂吸附/脱附, FTIR和荧光光谱分析等对复合材料的结构与性能进行了研究.     

介孔氧化硅孔径尺寸对Eu(Ⅲ)配合物的影响

分别以十六烷基三甲基溴化铵(CTAB)和聚乙氧基-聚丙氧基-聚乙氧基三嵌段共聚物(P123)为模板剂、正硅酸乙酯(TEOS)为硅源，采用水热法合成了有序介孔分子筛MCM-41和SBA-15。选择Eu(DBM)₃phen为客体，有序介孔氧化硅MCM-41和SBA-15为载体，分别在氯仿中进行分子组装，制备出具有较强发光性能的介孔复合材料Eu(DBM)₃phen/APTES-MCM-41(EAM)和Eu(DBM)₃phen/APTES-SBA-15(EAS)。采用XRD、TEM、N₂吸附-脱附和荧光光谱等对产物的结构与性能进行了分析。结果表明，Eu(DBM)₃phen组装进有序介孔氧化硅的孔道中后，发光纯度提高。而且孔径越小，发光纯度越高。选用较大孔径的SBA-15为载体，在不显著影响发光纯度的同时，可以获得较高的发光强度。     

介孔ZnO/SiO2复合材料的合成与性能表征

通过原位合成的方法,以[Zn(OH)x]-(x-2)(x＞2)为锌源、正硅酸乙酯(TEOS)为硅源,合成了孔壁为ZnO/SiO2复合结构的MCM-48型有序介孔分子筛,并通过XRD、XPS、N2吸附-脱附等温线等手段对样品进行了表征,结果表明,锌以正二价离子的形式均匀的分布在MCM-48分子筛的孔壁结构中.另外,适量掺锌所合成的Zn-MCM-48介孔材料仍然保持立方介孔的有序结构,具有较高的比表面积、较高的孔容和较宽的孔径分布.     

氨基功能化短孔道有序介孔材料H_2N-Zr-Ce-SBA-15的合成及吸附性能

以pluronic(P123)为模板剂,正硅酸乙酯(TEOS)为硅源,氯化氧锆和硝酸亚铈为无机前驱盐,N-(2-氨乙基)-3-氨丙基三甲氧基硅烷(AAPTS)为硅烷化试剂,采用后接枝法合成了氨基功能化六方板状短孔道有序介孔材料H2N-Zr-Ce-SBA-15(H2N-ZCS).采用小角X射线衍射(LXRD)、傅里叶变换红外(FTIR)光谱、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、热重分析、N2吸附/脱附等手段对H2N-ZCS进行了表征.结果表明AAPTS成功地嫁接到有序介孔材料上,H2N-ZCS仍保持了类似于传统SBA-15高度有序的二维六方相介孔结构,且孔道方向垂直于该六方板面.对阴离子染料酸性品红吸附实验表明,H2N-ZCS比H2N-SBA-15具有较强的吸附能力.这种功能化短孔道、大径轴比的六方板状介孔材料在吸附、分离及催化等领域中能更有效地促进分子的扩散传递.     

TEPA功能化SBA-15的CO_2吸附性能

以正硅酸乙酯(TEOS)为硅源,P123为模板剂,通过加入适量HAc及调整反应体系pH方式,采用水热及萃取法合成表面羟基含量较高的介孔SBA-15材料.以不同含量四乙烯五胺(TEPA)对SBA-15进行功能化,获得氨基功能化介孔SBA-15材料.利用X射线衍射(XRD)、N2吸-脱附、傅里叶红外光谱(FT-IR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、元素分析等手段对材料结构性能进行表征.以不同含量TEPA功能化介孔SBA-15为吸附剂,对CO_2进行吸附,考察了吸附温度、CO_2浓度、水等对吸附效率的影响.实验结果表明,常温、常压下30%TEPA功能化介孔SBA-15的CO_2吸附量最高,且重复使用性能良好.     

Fe_3O_4/SiO_2-NH_2磁性介孔纳米粒子的制备及其对酸性品红的吸附

采用共沉淀法,合成了由两亲性嵌段共聚物聚(苯乙烯)-b-聚(甲基丙烯酸聚乙二醇酯)(PSt-bPMAPEG)修饰的Fe_3O_4-聚合物复合纳米粒子。以十六烷基三甲基溴化铵(CTAB)为模板剂,正硅酸乙酯(TEOS)为硅源,N-(2-氨乙基)-3-氨丙基三甲氧基硅烷(AAPTS)为功能化试剂,制备了氨基功能化介孔材料Fe_3O_4/SiO_2-NH2。采用X射线衍射(XRD),傅里叶变换红外光谱(FT-IR),透射电子显微镜(TEM),N_2吸附/脱附等手段对Fe_3O_4/SiO_2-NH2进行了表征。结果表明,成功制备粒径约为50nm,孔径分别为3.3nm和42.9nm的Fe_3O_4/SiO_2介孔粒子。将磁性材料对水中酸性品红进行吸附性能研究,探讨了Fe_3O_4/SiO_2-NH2对染料酸性品红的吸附效率。结果表明:Fe_3O_4/SiO_2-NH2的用量为10mg,吸附时间为3.5min,溶液起始浓度为0.25mmol·L-1时吸附率达93.32%。     

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%.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.