微波消解-电感耦合等离子体质谱法测定车用催化剂中铂、钯、铑

提出了电感耦合等离子体质谱法同时测定车用催化剂中铂、钯和铑的含量。样品0.100 0g经盐酸6mL、硝酸3mL、氢氟酸1mL和水4mL消解,选择195Pt、105Pd和103 Rh为待测同位素。铂、钯和铑的检出限(3σ)分别为0.003,0.5,0.002μg·L-1。方法用于5种催化剂样品的分析,测定结果与另两家实验室测定结果相一致。铂、钯和铑的回收率在85.5%～101%之间。     

石墨炉原子吸收光谱法测定矿石中铂、钯、铑、铱

矿石样品铂、钯、铑和铱经铅试金富集,所得金属合粒用硝酸-盐酸溶解,用石墨炉原子吸收光谱法测定矿石样品中铂、钯、铑和铱的含量。在优化的石墨炉工作条件下测得:铂的质量浓度在20～150μg.L-1、钯在15～120μg.L-1、铑和铱在6～100μg.L-1范围内与其吸光度呈线性关系,检出限(3s/k)依次为4.6,4.0,1.5,1.5μg.L-1。方法用于分析了2种矿石国家标准物质(GBW 07341、GBW 07342),测定结果与认定值相符。方法的回收率在87.6%～105.5%之间。测定值的日内和日间相对标准偏差(n=7)分别在2.8%～3.6%和3.5%～4.7%之间。     

碱熔-碲共沉淀分离-电感耦合等离子体原子发射光谱(ICP-AES)法测定废弃环保催化剂中铂钯铑

准确测定废弃环保催化剂中铂、钯、铑含量,是实现废弃环保催化剂贵金属高效回收和处置的重要保障技术条件之一,对回收铂族金属、湿法冶金生产物料平衡考察、保证买卖双方公平、公正交易等都具有重要的意义。采用碱熔分解废弃环保催化剂样品,碲共沉淀富集铂、钯、铑并与共存离子分离,采用电感耦合等离子体原子发射光谱法（ICP-AES）测定铂、钯、铑含量。结果表明,在1.2~2.7 mol/L盐酸体系中,加入碲沉淀剂,以二氯化锡为还原剂,能完全沉淀富集铂、钯、铑。铂、钯、铑校准曲线的线性范围为0.50～50.00 μg/mL,线性相关系数分别为0.99998、0.99996、0.99997;铂、钯、铑的检出限分别为2.6 μg/g、0.9 μg/g、1.2 μg/g;方法中铂、钯、铑的测定范围为25～25000 μg/g。按照实验方法测定废弃环保催化剂中铂、钯、铑,结果相对标准偏差(RSD,n=11)为0.2%～3.6%;加标回收率为96%～109%     

电感耦合等离子体质谱法测定汽车尾气净化催化剂中铂、钯、铑含量

汽车尾气净化催化剂样品经过氧化钠熔融,用热水浸出,加入盐酸酸化后,分取部分试液用电感耦合等离子体质谱法测定其中铂、钯、铑的含量。选择镉(~(111)Cd)和铊(~(203)Tl)作为内标元素。铂、钯、铑的检出限(3s)分别为0.048,0.056,0.019μg·g~(-1)。方法用于5件催化剂样品的分析,测定结果与光度法测定结果相一致。铂、钯、铑的平均回收率分别为100.0%,100.0%,99.8%;相对标准偏差(n=12)分别为1.3%,1.0%,1.6%。     

高效液相色谱法测定汽车尾气催化剂中铂、钯和铑的研究

研究了用 2 羟基萘 1 亚甲基若丹宁(HNPRN) 为柱前衍生试剂,以 Zorbax StableBound (4.6 mm×50 mm, 1.8μm) 快速分离柱为固定相,62%的甲醇(内含0.5%的乙酸)为流动相,高效液相色谱分离,二极管矩阵检测器检测测定铂、钯和铑的方法,三种贵金属元素的络合物在2.0 min内可达到基线分离。根据信噪比(S/N=3)得各金属离子的检出限分别为:铂 1.0μg·L-1,钯0.6μg·L-1,铑0.8μg·L-1,方法用于汽车尾气催化剂中痕量铂、钯和铑的测定,相对标准偏差在1.4%~1.6%之间,结果满意。     

超级微波消解电感耦合等离子体质谱法测定车用陶瓷催化剂中铂、钯、铑

建立了一种检测车用陶瓷催化剂中铂、钯、铑的超级微波消解电感耦合等离子体质谱法.通过单因素试验和正交试验优化酸配比、称样量、消解温度、消解时间及回流溶剂参数,确定了最佳消解方法:0.1 g样品中加入1 mL盐酸、5 mL硝酸、1 mL氢氟酸,在220℃的消解温度下保持30 min,赶酸后加入10 mL逆王水于170℃回流...     

电感耦合等离子体质谱法测定铜冶炼渣尾矿中银及铂族元素的含量北大核心CSCD

样品(0.400 0 g)置于50 mL样品管中,加入盐酸-硝酸-水(3+1+4)混合液10 mL,饱和氟化氢铵溶液1.0 mL,经石墨消解仪斜坡升温进行消解。消解液冷却10 min,用水定容至50 mL。分取10.0 mL,用水稀释至20 mL,所得溶液采用电感耦合等离子体质谱法测定其中银及铂族元素(钌、铑、钯、铱、铂、金)的含量。以标准加入法补偿基体效应制作标准曲线。在质谱分析中采用标准模式。7种元素的检出限(3s)在0.01~0.80μg·L^(-1)之间。按标准加入法进行回收试验,回收率在94.0%~105%之间,相对标准偏差(n=11)在0.70%~2.1%之间。按上述方法分析铜冶炼渣尾矿样品,结果与石墨炉原子吸收光谱法测定结果基本一致。     

硫化镍试金富集-催化光度法测定痕量铑

在铑的硫酸配合物催化高碘酸钾氧化甲基红退色反应的基础上 ,提出了催化光度测定痕量铑的新方法。铑质量浓度在 0～ 0 .1 μg/mL范围内符合比尔定律 ,测定下限为 4× 1 0 - 3μg/mL。对于试样中质量分数为 1 6× 1 0 - 5%Rh的测定 ,RSD为 9 2 %,平均回收率为 89%。测定之前 ,痕量铑用小硫化镍试金富集分离。方法已用于原矿和尾矿中痕量铑的分析。     

电感耦合等离子体质谱法测定铜冶炼渣尾矿中银及铂族元素的含量

样品(0.400 0 g)置于50 mL样品管中,加入盐酸-硝酸-水(3+1+4)混合液10 mL,饱和氟化氢铵溶液1.0 mL,经石墨消解仪斜坡升温进行消解。消解液冷却10 min,用水定容至50 mL。分取10.0 mL,用水稀释至20 mL,所得溶液采用电感耦合等离子体质谱法测定其中银及铂族元素(钌、铑、钯、铱、铂、金)的含量。以标准加入法补偿基体效应制作标准曲线。在质谱分析中采用标准模式。7种元素的检出限(3s)在0.01~0.80μg·L~(-1)之间。按标准加入法进行回收试验,回收率在94.0%~105%之间,相对标准偏差(n=11)在0.70%~2.1%之间。按上述方法分析铜冶炼渣尾矿样品,结果与石墨炉原子吸收光谱法测定结果基本一致。     

铑(Ⅲ)-偶氮氯膦pA-溴酸钾褪色反应催化光度法测定痕量铑

报道了以铑（Ⅲ）催化溴酸钾氧化偶氮氯膦pA为基础测定痕量铑的催化光度分析法,建立了一种在水相中直接测定痕量铑（Ⅲ）的新方法。铑（Ⅲ）含量在5~30μg/L范围内符合比耳定律,检出限为5μg/L,本法用于铂-铑催化剂中铑的测定,结果满意。     

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.