粒度可调纳米CuO的制备及其表面硫化研究

用Cu(NO₃)₂·3H₂O为原料,25%氨水为配位剂,用NaOH做沉淀剂,在不同醇-氨水体系中用配位沉淀法制备粒径可调的纳米CuO。通过热重差热分析法(TG-DTA)分析前驱体的组成并得到煅烧最佳温度。在制备前驱体过程中,探究了反应体系溶剂分别为乙醇、正丁醇、正辛醇时对产物粒径的影响,实验结果表明:随着醇溶剂中碳链的增长,得到纳米CuO的比表面积依次增大,粒度依次减小。将纳米CuO与硫单质混合,在通入氮气的管式炉中以200 ℃加热90 min,可以得到表面硫化的CuO(CuO/CuS),利用X-射线粉末衍射(XRD)和红外吸收光谱(FT-IR)对纳米CuO和CuO/CuS进行表征。最后将纳米CuO和CuO/CuS分别对乙基黄原酸钾进行吸附,结果表明CuO/CuS对乙基黄原酸钾吸附能力明显增强,进而证明氧化铜表面发生了硫化。     

滴定法测定碱金属黄原酸盐

在碱性条件下，CS2和醇反应所生成的有机盐总称黄原酸盐。黄原酸钾(钠)又称乙基黄原酸钾(钠)、乙基二硫代碳酸钾(钠)，为白色或浅黄色固体粉末，有刺激性气味，易溶于水、乙醇中。工业上用作橡胶硫化促进剂，农业上用于作物的干燥剂。黄原酸钠还可作为医用防腐剂及杀菌剂，黄原酸钾是医药甲砜霉素的中间体，也用作分析试剂。     

超级铝热剂Al/CuO前驱体的制备、表征、热分解机理及非等温分解反应动力学

以硝酸铜、无水乙醇、1,2-环氧丙烷和纳米铝粉为原料, 在超声振荡条件下, 采用溶胶-凝胶法制备了纳米复合含能材料——超级铝热剂Al/CuO的前驱体. 利用热重-差示扫描量热-傅里叶变换红外-质谱(TG- DSC-FTIR-MS)联用技术, 研究了纳米Al/CuO溶胶-凝胶前驱体的热行为和分解过程及机理. 利用不同升温速率下的TG-DTG分析, 研究了纳米超级铝热剂Al/CuO的溶胶-凝胶前驱体的热分解反应机理, 采用了6种动力学分析方法进行动力学参数计算, 得到前驱体分解反应的表观活化能、反应级数、频率因子等动力学参数, 纳米Al/CuO前驱体分解反应的动力学方程为: dα/dt=10^14.0×4α^3/4exp(-2.0×10⁴/T).     

吸附法制备CuO-Ag/SiO2纳米复合物

利用吸附法原位制备CuO/SiO2、CuO-Ag/SiO2纳米复合物,研究了不同吸附质体系中预负载的纳米Ag粒子对CuO的影响。结果表明:Ag粒子对CuO的影响因吸附质的不同而不同。以Cu(Ac)2为吸附质,纳米Ag几乎没有影响;以NaOH为吸附质,纳米Ag使得CuO的晶粒粒径增大。这一结果与铜物种对Ag晶粒粒径的影响规律完全不同。通过比较不同吸附质的吸附行为,Cu(OH)2与硅胶表面的相互作用被认为是导致这一现象的原因。     

高度单分散聚乙烯基倍半硅氧烷球形纳米粒子的制备及性能

在水溶液中, 以乙烯基三乙氧基硅烷(VTES)为前驱体, 氨水(NH₃ · H₂O)为催化剂, 在表面活性剂十二烷基苯磺酸钠(SDBS)存在下, 通过溶胶-凝胶法成功合成了具有不同粒径、 高度单分散的聚乙烯基倍半硅氧烷(PVSQ)球形纳米粒子. 研究结果表明, 催化剂NH₃ · H₂O与表面活性剂SDBS的用量对PVSQ的粒径和粒径分布影响很大, 而前驱体VTES的用量对PVSQ的粒径无明显影响. 通过场发射扫描电子显微镜(FESEM)、 傅里叶变换红外光谱(FTIR)、 X射线光电子能谱(XPS)及热重(TG)分析对产物的形貌、 粒径和粒径分布、 结构及热性能进行了表征.     

反相微乳液介质中纳米Sm2O3的制备

用十六烷基三甲基溴化铵(CTAB)/正丁醇/正辛烷/钐盐水溶液(氨水)所形成的反相微乳液体系, 控制合成Sm2O3球形纳米粒子. 绘制出25 ℃下CTAB/正丁醇/正辛烷/钐盐水溶液(氨水)体系的拟三元相图, 得到了反相微乳液区.在此反相微乳区内合成了Sm2O3的前驱体, 对前驱体进行热分析(TG-DSC), 确定了得到纳米Sm2O3产物的适宜焙烧温度为900 ℃, 并考察了微乳液中反应物浓度、反应时间等因素对合成产物的影响. 采用X射线衍射(XRD)、透射电镜(TEM)、激光粒度仪(NSA)、荧光光谱(FS)仪等分析方法对Sm2O3产物的形貌、晶形、粒径及荧光性质进行了表征. 结果表明, 25 益下利用反相微乳液法, 成功地制备了粒径分布较窄、分散性良好的球形纳米Sm2O3粒子, 粒径约20 nm左右, 且表现出较强的荧光性质.     

合成ZnO纳米阵列及刺突状CuO/ZnO异质结

采用低温水热法在掺氟SnO₂ (FTO)导电玻璃表面制备ZnO纳米阵列, 研究了前驱体溶液浓度摩尔配比对ZnO纳米阵列形貌、光学性能及其生长机理的影响. 研究发现, 随着前驱体溶液浓度摩尔配比的增加, ZnO纳米阵列形貌及光学性能也随之变化. ZnO纳米阵列高度逐渐降低, ZnO纳米阵列直径和光学带隙值大体上出现先增大后降低的趋势. 而当前驱体溶液(Zn(NO₃)₂:环六亚甲基四胺(HMT, C₆H₁₂N₄))浓度摩尔配比为5:5时, 其光学禁带值(3.2 eV)接近于理论值. 结果显示制备ZnO纳米阵列的最优浓度摩尔配比为5:5. 随后选用最优浓度摩尔配比下制备的ZnO纳米阵列为基底, 通过一种两步溶液法成功在其表面制备刺突状CuO/ZnO异质结.从场发射扫描电镜(FE-SEM)结果中可以清楚看见, 大量的CuO纳米粒子沉积在ZnO纳米阵列表面形成刺突状异质结结构.研究发现该CuO/ZnO纳米异质结相对于纯ZnO纳米阵列在紫外光下光催化性能明显增加. 最后, 讨论了CuO/ZnO纳米异质结光催化机理.     

反相微乳液介质中纳米Sm2O3的制备

用十六烷基三甲基溴化铵(CTAB)/正丁醇/正辛烷/钐盐水溶液(氨水)所形成的反相微乳液体系,控制合成Sm2O3球形纳米粒子.绘制出25℃下CTAB/正丁醇/正辛烷/钐盐水溶液(氨水)体系的拟三元相图,得到了反相微乳液区.在此反相微乳区内合成了Sm2O3的前驱体,对前驱体进行热分析(TG-DSC),确定了得到纳米Sm2O3产物的适宜焙烧温度为900℃,并考察了微乳液中反应物浓度、反应时间等因素对合成产物的影响.采用X射线衍射(XRD)、透射电镜(TEM)、激光粒度仪(NSA)、荧光光谱(FS)仪等分析方法对Sm2O3产物的形貌、晶形、粒径及荧光性质进行了表征.结果表明,25℃下利用反相微乳液法,成功地制备了粒径分布较窄、分散性良好的球形纳米Sm2O3粒子,粒径约20 nm左右,且表现出较强的荧光性质.     

壳聚糖修饰的Pt纳米粒子

以氯铂酸为前驱体,硼氢化钠为还原剂,壳聚糖为保护剂,通过化学还原法,在室温条件下制备了Pt纳米粒子.透射电镜(TEM)显示纳米粒子的粒径在28.5nm左右,X-射线衍射(XRD)表明纳米粒子的晶型为面心立方结构,X-光电子能谱(XPS)和红外(FTIR)证实了壳聚糖包覆在纳米粒子表面,热重分析(TGA)表明纳米粒子表面的壳聚糖含量大约为52.8％.     

核壳结构CdS/CuS纳米复合材料的制备及光催化性能

以乙酸镉、 2-巯基苯并噻唑、 硫化钠和氯化铜为原料, 依次利用液相热分解与离子吸附法, 改变CdS晶化时间及含量, 制备了4种CdS/CuS纳米复合材料. 研究结果表明: CdS/CuS纳米复合材料呈类球形核壳结构, 改变CdS晶化时间可以控制CdS/CuS纳米复合材料粒径大小; CdS的晶化时间为10 min, CdS与CuS摩尔比为4∶1的纳米复合材料光催化活性最佳, 25 min内对RhB和MB的降解效率均达到99%.     

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.     

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.     

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.     

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.     

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.     

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.