沉淀剂对水热法制备分等级氧化铁纳米结构及其Cr(Ⅵ)吸附性能的影响

以硫酸铁为铁源、硫脲、氟化钠和尿素分别为沉淀剂,采用水热法成功地制备了分等级微米级球状氧化铁粒子、六方柱状粒子相互交织的微米级氧化铁团聚体等。采用X射线衍射、扫描电镜、N2吸附-脱附、磁滞回线和UV紫外分光光度计等测试手段,对比研究了上述沉淀剂对产物微结构、形貌、织构性质及其对剧毒Cr(Ⅵ)吸附性能的影响。结果表明,以硫脲为沉淀剂制得氧化铁的结晶度最高,其晶粒大小为49.7nm,并具有最高的比表面积13.0m2·g-1、最大的孔容0.092cm3·g-1和平均孔径28.6nm;该氧化铁具有最佳的Cr(Ⅵ)吸附性能,30min即达到吸附平衡,饱和吸附量达202.8mg·g-1,并且符合Langmuir单分子层吸附模型;该氧化铁还具有一定的磁性,通过外加磁场可以实现吸附Cr(Ⅵ)后的吸附剂与溶液的彻底分离,因而在重金属废水处理领域显示出良好的应用前景。     

纳米片聚结Co_3O_4微球催化甲苯燃烧（英文）

采用乙二胺辅助的水热法制备了纳米片聚结的Co3O4微球.利用多种分析技术表征了其物化性质,并评价了其对甲苯燃烧的催化活性.结果表明,由添加1.0 ml乙二胺经140°C水热处理12 h后制得的Co3O4样品呈纳米片聚结的微球状表面形貌.Co3O4微球样品的比表面积约为66 m2g-1.与体相Co3O4样品相比,Co3O4微球样品具有较高的氧吸附物种浓度和较好的低温还原性.当空速为20000 ml g-1h-1时,在Co3O4微球样品上甲苯转化率达到50%和90%时的反应温度分别为230和254°C.这与该样品具有较大的比表面积、较高的氧吸附物种浓度和较好的低温还原性相关.     

碳包覆Na2Ti6O13纳米管的电化学性能研究

以金红石型TiO2和NaOH为原料,由水热反应制备Na2Ti6O13纳米管.然后,在含有0.1 mol.L-1NaOH的葡萄糖水溶液中反应4 h制得碳包覆的Na2Ti6O13纳米管.X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等分析表明,该碳包覆Na2Ti6O13纳米管外径约14～19 nm,内径约2～5 nm,长度为数百纳米,有一层厚度约为2 nm的碳层包覆在纳米管外壁.以其作为锂离子电池负极材料,恒电流充放电测试表明,在50 mA.g-1电流密度下首周可逆容量达到161 mAh.g-1,循环100周后容量保持在147 mAh.g-1.相比于Na2Ti6O13纳米管,提高了20%以上.电流密度升至1600 mA.g-1充放电,碳包覆Na2Ti6O13纳米管可逆容量仍有70 mAh.g-1左右,远高于Na2Ti6O13纳米管,表现出良好的倍率性能.     

α-Fe_2O_3纳米立方体和纳米棒组装空心微球的可控合成及其磁学性能

在0.15mol/LCl-和0.05mol/LSO42-的存在下,通过Fe3 溶液140℃水热反应12h分别得到α-Fe2O3纳米立方体和α-FeOOH纳米棒自组装的微球,将得到的α-FeOOH纳米棒自组装微球经600℃热处理2h后转化为α-Fe2O3纳米棒组装空心微球.利用X射线衍射仪、扫描电子显微镜、透射电子显微镜和红外光谱对所得产物进行表征和分析.结果表明,所制备的单分散的α-Fe2O3纳米立方体为六方单晶结构,其边长为500nm.直径为2~4.5μm的空心微球是由直径约150nm的α-Fe2O3纳米棒组装而成.研究了Cl-和SO42-在纳米立方体和空心微球形成过程中的作用,提出了可能的生长机理.在室温下测试了α-Fe2O3纳米立方体和α-Fe2O3纳米棒自组装微球的磁学特性,其矫顽力和剩余磁化强度分别为2858.3Oe(1Oe=79.58A/m)和0.195emu·g-1(1emu·g-1=15.7914×10-9A·m2·kg-1),218.87Oe和0.071emu·g-1.     

水热法合成α-MnO2纳米棒及其电化学性能

以KMnO4、氧化石墨(GO)和硫酸为原料,在120℃水热条件下3 h成功合成了直径为10~20 nm,长度为300~400 nm的α-MnO2纳米棒。研究发现GO的引入降低了纳米棒的制备温度,缩短了反应时间。电化学测试结果表明,在1 mol.L-1Na2SO4中性水系电解液中,该纳米棒表现出良好的电容性能,当扫描速率分别为2 mV.s-1和5 mV.s-1时,比电容分别为276 F.g-1和240F.g-1;该纳米材料是一种潜在的电化学电容器电极材料。     

聚合氯化铝制备拟薄水铝石及γ-Al2O3的研究Ⅱ——表面活性剂影响探讨

本实验采用自制的聚合氯化铝溶液为原料,利用溶胶-凝胶法制备拟薄水铝石及其衍生物γ-Al2O3,采用XRD、TEM和N2吸附法对样品进行表征和分析,探讨了不同pH值、不同合成温度以及不同pluronic表面活性剂对产物结构性质的影响。结果表明:当pH值为8.5时水合氧化铝以拟薄水铝石为主;当温度为70℃时制备的产物为拟薄水铝石晶相。随着表面活性剂L64、L65和F68分子量的增加,生成的拟薄水铝石及其衍生物γ-Al2O3的物相结晶度升高,但产物的晶相没有改变。所制备的拟薄水铝石在500℃焙烧6 h后均得到γ-Al2O3,其中表面活性剂为L65时扩孔效果最佳,比表面积、孔容和孔径分别为231 m2.g-1、0.28 cm3.g-1和4.52 nm。     

水溶-蒸发法制备LiFePO4/C及其电化学性能研究

由LiH2PO4和FeC2O4.2H2O作原料、柠檬酸为碳源,用水溶-蒸发法制备了LiFePO4/C正极样品.采用X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)分析、观察样品.用充放电曲线和电化学交流阻抗(EIS)谱图测试LiFePO4/C电极.结果表明,700℃焙烧的LiFePO4/C样品(碳量3.03%,by mass)结晶度高、无杂相、颗粒粒径100 nm,其表面包覆约5 nm碳层.该电极0.5C、2C、5C和10C(1C=170 mA.g-1)倍率放电,其比容量分别为148.2 mAh.g-1、142.4 mAh.g-1、127.4 mAh.g-1和108.5 mAh.g-1,循环寿命曲线稳定.     

静电纺丝法制备铁酸锌中空纤维及其磁学性能

以锌盐、铁盐和聚乙烯吡咯烷酮(PVP)为原料,通过静电纺丝法先制备PVP/硝酸盐复合纤维,这些复合纤维以5℃·min-1的升温速率加热到500℃并保温3h,最终得到铁酸锌(ZnFe2O4)中空纤维.通过X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)以及振动样品磁强计(VSM)等分析手段对中空纤维的晶体结构、形貌和磁学性能进行了研究.结果显示,ZnFe2O4中空纤维属于尖晶石结构,高温处理后仍能保持一维结构,纤维直径在200-400nm之间,纤维壁由大小为25nm的颗粒堆积而成.室温磁化结果显示制备的ZnFe2O4中空纤维具有超顺磁性,在10kOe的磁化强度为2.03emu·g-1.     

CuSAPO-5分子筛的合成、表征及对甲苯吸附性能

采用水热合成法,以三乙烯四胺(TETA)为模板剂,合成Cu SAPO-5分子筛。通过扫描电子显微镜(SEM)、粉末X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、热重(TG)、N2吸附及元素分析等手段对分子筛样品进行表征,考察了不同硅铝比对合成分子筛晶体的影响,并测定了分子筛样品对甲苯的吸附性能。结果表明,将合成液的p H值调节为4.8~5.0,于150~170℃晶化1d,可合成晶体形貌为球体的Cu SAPO-5分子筛,粒径约为30μm。分子筛样品具有较好的热稳定性,仍保持了SAPO-5分子筛的AFI骨架结构,属于微孔分子筛,孔径约为0.70nm,比表面积约为265 m2·g-1。元素分析结果表明分子筛中P、Si、Al和Cu的含量分别为12.56%、4.48%、7.17%和6.25%。样品对甲苯的吸附约在120 min时达到饱和,吸附量约为180 mg·g-1。     

不同铈添加量对CeO2-ZrO2-Al2O3材料性能的影响

采用共沉淀法制备了一系列不同铈添加量的CeO2-ZrO2-Al2O3(CZA)储氧材料,并通过XRD、低温N2吸附-脱附、氧脉冲吸附(OSC)和H2-TPR等手段进行了表征。XRD结果表明,在1 000和1 100℃高温焙烧后,当CeO2添加量为8%时样品具有最好的结构稳定性能。N2吸附-脱附结果表明,CeO2添加量为8%时样品具有最好的织构性能,1 000℃时,比表面积和孔容分别为:136.6 m2.g-1和0.38 mL.g-1;1 100℃时,比表面积和孔容分别为:83.7 m2.g-1和0.23 mL.g-1。OSC结果显示,CeO2添加量为8%时样品具有最大的储氧量,1 000℃和1 100℃分别为70μmol.g-1和31μmol.g-1。H2-TPR结果表明,CeO2添加量为8%时样品具有最佳的还原性能。     

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.