从化工废水制备高品质二水合硫酸钙晶须的研究

以含有硫酸根离子的化工废水和钙盐制得的硫酸钙为原料,十六烷基硫酸钠为分散剂,氯化镁为晶型助长剂,用硫酸调节p H,采用水热法制备二水合硫酸钙晶须。研究了反应温度和降温速度对二水合硫酸钙晶须的影响,通过扫描电镜(SEM)测量硫酸钙晶须的长径比,用热重分析仪研究了硫酸钙晶须的热重行为。结果表明,最佳反应温度为125℃、反应降温速度为30℃/30 min,长径比可达80以上。     

常压酸化法从磷钾伴生矿酸浸液中制备硫酸钙晶须

以磷钾伴生矿的盐酸浸出液为介质,研究常压酸化法制备硫酸钙晶须,分别考察了不同硫酸浓度、加热温度、n(SO_4~(2-))/n(Ca~(2+))、滴加速率以及搅拌转速等操作条件对硫酸钙晶须长径比的影响.实验结果表明:在硫酸浓度为0.87 mol/L、加热温度为105℃、n(SO_4~(2-))/n(Ca~(2+))=1.2、滴加速率为2.5 mL/min、搅拌转速为166 r/min较佳的条件下,可制得长径比为32的二水硫酸钙晶须.     

半水硫酸钙晶须的水化机理及稳定性调节

通过探讨半水硫酸钙晶须(HCSW)贮存过程在空气中形貌和晶形的变化,研究了半水硫酸钙晶须的水化机理,分析了不同处理方法对其稳定性的调节。研究发现,HCSW的水化是由晶须表面的-OH基团和Ca^2+活性位点以及HCSW存在的内部通道引起的,煅烧和二元醇改性均可提高硫酸钙晶须的耐水性。结果表明,煅烧后,半水硫酸钙晶须转化为无水可溶硫酸钙晶须和无水死烧硫酸钙晶须,易于水化的内部通道消失,耐水性增强;水热合成过程二元醇的加入,可利于醇羟基吸附在HCSW的(200)、(020)和(220)表面,阻止H2O分子中羟基在晶须表面的吸附,进而提高晶须的耐水性,当添加剂为三乙二醇(TEG)且浓度为18.8 mmol·L^-1时,HSCW在空气中耐水稳定性不小于7 d。     

高长径比钛酸钾晶须的合成及其结构研究

用水热法合成一种长径比大于2500的钛酸钾晶须。经X射线粉末衍射分析表明，该晶须属于正交晶系，获得了一种新的晶须。通过考察温度、碱度、配料比、反应时间等因素对晶须形貌、产率及其结构的影响，得到制备该类晶须的最佳条件，并尝试探讨了其形成机理。     

半水硫酸钙晶须的水化机理及稳定性调节（英文）

通过探讨半水硫酸钙晶须(HCSW)贮存过程在空气中形貌和晶形的变化,研究了半水硫酸钙晶须的水化机理,分析了不同处理方法对其稳定性的调节。研究发现,HCSW的水化是由晶须表面的-OH基团和Ca~(2+)活性位点以及HCSW存在的内部通道引起的,煅烧和二元醇改性均可提高硫酸钙晶须的耐水性。结果表明,煅烧后,半水硫酸钙晶须转化为无水可溶硫酸钙晶须和无水死烧硫酸钙晶须,易于水化的内部通道消失,耐水性增强;水热合成过程二元醇的加入,可利于醇羟基吸附在HCSW的(200)、(020)和(220)表面,阻止H_2O分子中羟基在晶须表面的吸附,进而提高晶须的耐水性,当添加剂为三乙二醇(TEG)且浓度为18.8 mmol·L~(-1)时,HSCW在空气中耐水稳定性不小于7 d。     

电解法制备纳米Cu2O及其光催化性能的研究

以紫铜板为阳极,钛网为阴极,十六烷基三甲基溴化铵(CTAB)为添加剂,采用离子膜电解法制备纳米Cu2O晶须。由X射线衍射(XRD)、透射电镜(TEM和HRTEM)、比表面积(BET)等手段对产物进行了表征。结果表明,所制备的纳米Cu2O直径约10~30nm,长度约500nm,且Cu2O的生长趋势具有〈111〉面择优取向。还发现纳米Cu2O晶须的晶面上有许多孔洞,使所制备的Cu2O具有良好的光吸收能力和一定的光催化活性。此Cu2O样品降解有机染料活性艳红(X_3B)的光催化性能的结果表明,其在1h内降解活性艳红的效率达到96.4%。     

介孔氧化镍的复合表面活性剂模版法制备及表征

用六水合硝酸镍为镍源,尿素为沉淀剂,以少量的复合表面活性剂(SDS/P123,CTAB/P123,CTBA/SDS)为模板水热制备了介孔氧化镍。分别采用热重-差示扫描量热(TG-DSC)、傅立叶红外光谱(FTIR)、X射线衍射(XRD)、氮气吸附脱附、扫描电子显微镜(SEM)、透射电子显微镜(TEM)对产物的结构和形貌进行了表征。用循环伏安法,恒电流充放电和交流阻抗谱等对材料进行了电化学性能的测试。结果表明,以复合表面活性剂SDS/P123为模板制备的介孔氧化镍有最大的比表面积、孔径和比电容,且当SDS/P123质量比为2:1时,所制备的氧化镍比表面积、孔径和比电容分别为209 m2.g-1,0.407 cm3.g-1,265 F.g-1。     

半水硫酸钙晶须稳定化研究

使用多种稳定剂对半水硫酸钙晶须进行稳定化处理,研究了稳定剂用量、稳定化处理温度和时间等对半水硫酸钙晶须稳定性的影响。通过FTIR、SEM、DSC-TG和XRD对稳定化处理后的产物进行了表征,结果表明：在油酸钠用量0.3%,稳定化处理温度100 ℃,稳定化处理时间20 min的条件下,实现了半水硫酸钙晶须的稳定;油酸钠在晶须表面的吸附既有物理吸附又有化学吸附,并通过化学吸附在晶须表面形成了油酸钙。     

钕的氢氧化物和氧化物纳米线的制备及表征

以金属钕为起始原料，采用简单的碱性溶液下水热法制备出氢氧化钕纳米线。所得到的水热产物采用X-射线衍射、扫描电镜和透射电镜等进行了结构与形态表征。研究发现，水热处理的温度、碱液浓度和碱的种类等对水热产物的形貌、长径比和结晶状态有较大影响，提高水热温度和增加碱液浓度有利于氢氧化钕纳米线的生长。在相同水热反应温度(180 ℃)、水热时间(45 h)和碱浓度下，5 mol·L^-1 NaOH溶液体系制备的氢氧化钕纳米线具有较高纯度和较长的长径比，其直径为20～40 nm，长度为2～10 μm。该氢氧化钕纳米线在空气气氛下500 ℃烧结后形成具有体心立方结构的C型Nd₂O₃，该Nd₂O₃仍具有一维纳米线形貌。升高焙烧温度时产物的形貌和相结构都发生了明显变化。     

PSS辅助水热合成分级结构纳米γ-Al2O3及其CO2吸附性能增强

以AlCl_3·6H_2O为铝源、CH_3COOK为沉淀剂、聚苯乙烯磺酸钠(PSS)为结构调节剂,采用温和水热焙烧法成功地制备了系列对CO_2吸附性能增强的分级结构纳米γ-Al_2O_3。采用XRD、SEM和N2吸附-脱附等手段,对比研究了PSS浓度对产物物相结构、形貌、织构性质及其在室温下对CO_2吸附性能的影响。研究表明,PSS对产物形貌、织构性质及其CO_2吸附性能具有明显的调控作用。不添加PSS时产物表现为不规则的块状粒子,PSS浓度依次增加到2、4和6 g·L~(-1)后,产物分别表现为不规则的棒状团簇体微米级粒子、类球形棒状团簇体微米级粒子、相互交织的纤维状微米级粒子,并且其比表面积和孔容逐渐增加;添加PSS后产物的CO_2吸附量增加、吸附动力学加快,尤其是PSS浓度为6 g·L~(-1)时,相应产物的最高吸附量为0.68 mmol·g~(-1),6次循环再生后其吸附量仍基本保持稳定。     

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.     

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.     

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.