苯乙烯协助水热制备高催化活性ZnO管

采用苯乙烯微球为模板水热合成了直径为1~2μm,管壁厚度约200nm的ZnO管。用SEM和XRD对制得的样品进行表征,结果表明,醋酸锌浓度和水热时间在ZnO管的制备过程中起到重要作用。在实验结果的基础上,提出了ZnO管的形成机理。紫外-可见吸收光谱计算出ZnO管的禁带宽度为2.96eV,合成的ZnO管对罗丹明B具有很高的紫外光催化活性。     

离子液体中不同形貌ZnO纳米材料的合成及表征

在不同的咪唑基离子液体中通过微波加热合成出了ZnO的片状聚集体、棒状聚集体和塔棒聚集体等纳/微米结构, 考察了不同合成条件对ZnO形貌的影响, XRD表明产物为六方相纤锌矿ZnO结构, SEM和TEM表明产物形貌主要分为片的聚集体和棒的聚集体, 电子衍射表明ZnO棒具有单晶结构, 片的聚集体的PL谱表明在室温下这种形貌的ZnO具有很强的绿光发射和弱紫外光发射现象.     

分级结构ZnO六棱柱：制备及对5-取代-1氢四氮唑催化性能

以简单有效的液相法合成了具有分级结构的ZnO六棱柱,通过改变不同表面活性剂、碱源等反应条件调控ZnO的形貌,结果表明CTAB(十六烷基三甲基溴化铵)和六亚甲基四胺为合成ZnO六棱柱最佳的表面活性剂和碱源,通过研究CTAB的浓度以及反应时间对产品形貌的影响,初步提出了分级结构ZnO六棱柱的形成机理。对制备的ZnO六棱柱进行四氮唑催化性能研究,以不同取代腈为底物显示了良好的催化活性,产率大多在85%以上。     

水热合成掺Fe氧化锌复合材料及其光催化活性

以Zn(Ac)2•2H2O、Fe(NO3)3•9H2O和NaOH为原料,采用水热法合成了Fe掺杂ZnO复合材料。并用x射线衍射和扫描电子显微镜技术对合成样品的结构和形貌进行了表征,Fe掺杂ZnO合成产物为直棒状,直径为500 nm,长度为3 µm左右。样品的紫外可见漫反射分析,在300~500 nm紫外可见光区域均有强的吸收。利用Fe掺杂ZnO作为光催化剂降解有机染料,发现对于光催化降解有机染料有较好的降解功能,且光降解性能优于纯ZnO材料。     

水热合成Fe3+掺杂ZnO复合材料及其光催化活性

以Zn(Ac)2·2H2O、Fe(NO3)3·9H2O和NaOH为原料,采用水热法合成了Fe3+掺杂ZnO复合材料. 并用X射线衍射和扫描电子显微镜测试技术对合成样品的结构和形貌进行了表征. 结果表明,Fe3+掺杂ZnO合成产物为直棒状,直径为500 nm,长度为3 μm左右. 样品的紫外可见漫反射分析结果表明,在300～500 nm紫外可见光区域均有强的吸收. Fe3+掺杂ZnO作为光催化剂降解有机染料性能优于纯ZnO材料.     

咪唑类离子液体辅助水热法合成棒状微/纳米ZnO晶体

以醋酸锌和氢氧化钠为原料, 以水和含不同长度烷基链的咪唑类氯盐离子液体的混合物作为反应介质, 采用水热法合成出不同形貌的微/纳米ZnO晶体, 用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对合成的ZnO晶体进行表征. 研究了烷基链长度、 离子液体用量、 反应时间以及反应温度对形成棒状ZnO晶体形貌的影响. 实验结果表明, 所制备的棒状ZnO晶体样品均为六方晶系结构. 在棒状ZnO晶体的制备过程中, 控制反应温度, 选择不同的离子液体及其用量十分重要.     

具有核壳结构的ZnO纳米棒@Ni-Co双氢氧化物复合物纳米片阵列的制备及其电化学性能

通过两步水热合成法制备了具有核壳结构的ZnO纳米棒@Ni-Co双氢氧化物复合材料纳米片阵列.首先,以碳布为基底,水热法生成的ZnO沉积在碳布上形成ZnO纳米棒花簇.其次,以ZnO纳米棒为模板,水热法生成的Ni-Co双氢氧化物纳米片沉积在ZnO纳米棒表面,形成ZnO纳米棒@Ni-Co双氢氧化物纳米片复合材料阵列.形貌、结构分析和电化学性能测试表明,以碳布为基底,成功地合成了以ZnO纳米棒为模板并具有核壳结构的ZnO纳米棒@Ni-Co双氢氧化物复合材料纳米片阵列,该复合材料纳米片阵列具有较大的纵横比,且分散均匀.合成的ZnO纳米棒@Ni-Co双氢氧化物复合材料纳米片阵列具有良好的电化学性能,当电流密度为1 A/g时,其比电容值可达531.6 F/g,该复合材料在超级电容器电极材料领域具有良好的应用前景.     

反应性离子交换法合成纳米ZnO及其光催化性能

 以 ZnSO4 和 NaOH 为原料, 强碱性阴离子交换树脂为模板, 采用反应性离子交换法一步合成了高纯纳米 ZnO 晶体, 并运用扫描电子显微镜、X 射线衍射和紫外-可见光谱等技术对样品进行了表征, 初步探讨了合成机理. 结果表明, 制得的纳米 ZnO 晶体呈一维棒状, 它在树脂表面的形成过程与 ZnSO4 的初始浓度密切相关. 该 ZnO 样品对光催化降解甲基橙具有较高的活性和循环使用性能.     

溶胶凝胶辅助水热可控合成ZnO不同形貌分级结构光催化剂

以Zn(NO3)2·6H2O、柠檬酸和Na OH为原料,采用溶胶凝胶(sol-gel)辅助水热法,仅通过改变水热时间,就可得到片花、棒花及梭状3种不同形貌ZnO分级结构。利用XRD、SEM、UV-Vis DRS、光致发光光谱(PL)和氮低温吸附-脱附等手段对合成的ZnO样品进行了表征。推测了合成条件下不同形貌ZnO分级结构形成的机理。以活性翠兰(KGL)为模拟印染废水,考察了其光催化活性。结果表明,虽然所合成的不同形貌的ZnO样品在光照120 min后均能使KGL降解78%以上,但其中水热4 h得到的片花状ZnO光催化性能最好,可降解99%的KGL,这与其片花状的形貌、较大的比表面积、较多的表面氧缺陷和极性面有关。     

ZnO/CdS复合材料的合成与可见光催化性能

采用喷雾辅助气相沉积法在水热法合成的ZnO纳米线上沉积CdS纳米颗粒。采用X射线衍射仪（XRD）、激光拉曼仪（Raman）、扫描电镜（SEM）、透射电镜（TEM）、X射线光电子能谱分析谱（XPS）和紫外可见漫反射光谱等测试手段对复合光催化剂进行表征。结果表明,3~10 nm的CdS纳米粒子修饰在直径约为100 nm ZnO纳米线的表面。XPS和Raman表明复合材料中ZnO和CdS之间存在化学相互作用。可见光催化降解罗丹明B实验结果表明ZnO/CdS复合材料的催化性能优于单相CdS或ZnO,沉积时间为30 s合成的ZnO/CdS速率常数分别是CdS和ZnO的2.91和4.03倍,且具有较高的稳定性。ZnO/CdS复合材料光催化性能增强的可能原因为光吸收范围的拓展和光生载流子分离效率的提高。     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.