冶金炉料中二氧化硅和碳化硅的联合测定

提出冶金炉料中二氧化硅及碳化硅的联合测定方法，硝酸－氢氟酸－盐酸溶解二氧化硅，用硅氟酸钾容量法测定，残渣经焦硫酸钾溶解杂质，不溶碳化硅以重量法测定，经试样全分析及精密度考证，方法简便、可靠．     

以钨酸铅形式分离钨（VI）快速测定白钨矿中钙

以钨酸铅形式分离钨（ＶＩ）快速测定白钨矿中钙赵建为（昆明冶金研究院，６５００３１）白钨矿是一种以钨酸钙为主成份的矿物，测定钙时为消除钨（ＶＩ）的干扰，国内外分析工作者对此做了大量的工作。如试样碱熔，水浸取，可使钙与钨酸根分离［１］；酸溶时，钨以钨酸形...     

新的磷矿溶解法测磷

磷矿分析一般用盐酸、硝酸或王水加热溶矿,然后用重量法、容量法或比色法测定磷含量。据有些文章报导,对于某些磷矿,用盐酸或硝酸溶解,磷不能定量溶出。通常用浓酸溶矿需要长时间加热以驱除过量酸,致酸蒸汽严重污染环境。本文提出硝酸铝-柠檬酸稀溶液作为磷矿的特效溶剂,它既能快速把磷份定量溶出,又无毒气污染,且多余的溶剂对以后分析无干扰。试验证明,溶矿后能方便地应用钼酸喹啉重量法或磷钒钼黄比色法测磷。     

Cu(Ⅱ)模板法合成交联壳聚糖缩合水杨醛螯合树脂

壳聚糖可溶于酸性介质中并发生降解［１］,因此,利用壳聚糖制备螯合树脂时,需进行改性,使之转变为不溶不熔的交联型树脂．但交联后的壳聚糖虽不溶于酸,其吸附能力却比交联前明显降低［２］．模板合成法是制备具有一定“记忆”功能的高分子吸附螯合树脂的一种新方法,...     

430Ti钢中游离钛的比色测定

430Ti钢材主要用途是制作彩色电视机显像管固定阴罩的销钉。它含钛0.35—0.65%。对其中游离钛的含量有一定要求,在稀硫酸及稀盐酸中,金属钛溶解而化合钛则难溶,本文利用此特性,分离     

强酸型树脂催化L—苯丙氨酸甲酯化研究

１前言对酯化反应所用催化剂,一般使用强酸,如浓硫酸、浓盐酸等。另外,许多Ｌｅｗｉｓ酸,如三氟化硼、三氯化铝、氯化锌和硅胶等也能促进羰酸提供质子［１］。近年来的研究发现,强酸型阳离子交换树脂亦可用于催化某些酯化过程［２］。Ｌ－苯丙氨酸的甲酯化反应,传统...     

金属材料分析方法的选择和施行第四讲金属材料中钛的测定(续)

2.4　铝钛中间合金中钛的测定(此方法由上海材料研究化学分析研究室提供)测定范围:w(Ti)≥1%方法提要:试样0.5000g,置于500ml锥形瓶中,加入盐酸(1+1)20ml,作用缓慢时加热至试样全溶,滴加过氧化氢(ρ1.11g·ml-1)3～5滴,煮沸。如溶液不清,过滤至另个500ml锥形瓶中,用盐酸(5+95)洗涤沉淀及滤纸。如沉淀中有不溶性钛的化合物存在,须将沉淀及滤纸置于铂坩埚中灰化,用焦硫酸钾熔融,熔块用稀硫酸浸出后并入于主液中。加硫酸(ρ1.84g·ml-1)5ml,加热蒸发至冒硫酸烟,冷却,加盐酸(1+1)100ml,加热溶解盐类,加水至约150ml,加入碳酸氢钠2g和铝片2g,随即…     

酸功能化离子液体催化合成2-叔丁基蒽醌

以N-甲基咪唑、吡啶、1,4-丁烷磺内酯、对甲苯磺酸及硫酸为主要原料,经两步反应合成了4种酸功能化离子液体［MIM-BS］［TsO］(IL1)、 ［MIM BS］［HSO₄］(IL2)、 ［PY-BS］［TsO］(IL3)和［PY-BS］［HSO₄］(IL4),其结构和性能经¹H NMR, IR和TGA表征。以［MIM-BS］［TsO］为催化剂,催化2-(4-叔丁基苯甲酰基)苯甲酸(BB酸)合成2-叔丁基蒽醌,并对反应条件进行了优化。结果表明：IL1 0.4 g,n(IL)/n(BB酸)=0.5,于120 ℃反应9 h, 2-叔丁基蒽醌产率最高达90%,离子液体循环使用5次后催化活性无明显降低。     

燃料电池电极制作方法的研究

对燃料电池,性能良好的催化剂至关重要,它决定着大电流密度放电时的性能、成本和运行寿命［１］．但因电极上的反应是气、液、固三相反应,所以必须制备出高效的、结构合理的气体电极［２～３］,减小气相、液相传质阻力,提高三相接触性能,降低电极极化．Ｋ．Ｍｕｎｄ等［４～５］所制作的电极,气体扩散距离长,溶解气体的扩散电阻大．Ｒ．Ｐ．Ｉｃｚｋｏｗｓｋｉ等人［６］用ＰＴＦＥ（ｐｏｌｙｔｅｔｒａｆｌｕｏｒｏｅｔｈｙｌｅｎｅ,聚四氟乙烯）作疏水剂,在整个气体反应层制成气体扩散通道,改善了电极性能．后来,Ｓ．Ｍｏｔ…     

由硅酸酯合成单分散二氧化硅中碳的化学形态

单分散二氧化硅是指尺寸分布十分狭窄的二氧化硅颗粒．单分散颗粒在科学研究及工业应用中得到了广泛的应用［1］．单分散二氧化硅由正硅酸有机酯在氨催化下于醇溶液中水解缩合得到．硅酸酯的水解和缩合反应可用如下反应描述．总的反应式为：nSi（OR）4＋2nH20→nSiO2＋4nROH1956年Kolbe［2］发现正硅酸乙酯（TEOS）在碱催化下于乙醇溶剂中水解反应有时会形成均一颗粒二氧化硅以来，许多学者对这一反应体系进行了较为广泛的研究，提出了双分子缩合成核机理、单分子叠加生长机理、表面反应控制生长机理、扩散控制生长机理和微晶核团聚生…     

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.     

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.     

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.     

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.