化学光谱法测定6N氧化铕中14个稀土杂质元素

本文利用有铕易被还原的特性，将铕还原为二价进行预分离，继以Ｐ５０７萃淋树脂柱进行二次分离，光谱测定富集物中１４个稀土杂质元素，本方法富集倍数高达２０，０００倍，化学光谱测定了下限为０．６５μｇ／ｇ（∑ＲＥ）可满足６氧化铕产品分析的要求。     

化学光谱法测定5N氧化钆中14个稀土杂质元素

报道了化学光谱法测定５Ｎ高纯氧化钆中１４个稀土杂质元素，在Ｐ５０７萃淋树脂色层柱上分离氧化钆中稀土杂质元素，分别采用定量分离Ｌａ－Ｓｍ及Ｔｂ－Ｌｕ＋Ｙ和部份分离Ｅｕ的方法，并相应地采用碳粉吸附法和碳粉粉末法进行光谱测定。分离时间为３．５ｈ，测定下限为１．２μｇ／ｇ（ＲＥ）。     

感耦等离子体质谱法测定高纯氧化镥中14个痕量稀土杂质

本文报道了用感耦等离子体质谱法（ＩＣＰ－ＭＳ）测定高纯氧化镥中１４个稀土杂质的方法。镥基体对测定元素无谱线干扰，但对测定信号产生显著抑制作用。加入内标后有效地补偿了这种基体抑制效应，方法检出限为０．００５～０．０３ｎｇ／ｍＬ。样品加标为０．０１μｇ时，回收率为９０％～１０３％。精密度（ＲＳＤ）为１．４％～４．２％。方法简单，不需分离富集，样品消耗量少（１０ｍｇ）。１４个稀土元素的总测定下限（１０）可达０．５８μｇ／ｇ可直接测定纯度为９９．９％～９９．９９９９％的氧化镥中稀土杂质。     

高纯氧化钆中稀土杂质的化学光谱分析

化学光谱法是高纯稀土分析的主要方法,近年来,以P507萃淋树脂为固定相的萃取色谱法,对稀土元素的分离进行了系统的研究。本工作是在高纯氧化钕中14个稀土杂质化学光谱分析的基础上,研究高纯氧化钆中稀土杂质的分离条件。在φ14×1000的恒温色层柱上,以盐酸为淋洗剂,偶氮胂Ⅲ柱上显色,梯度淋洗,分离富集高纯氧化钆中稀土杂质,富集倍数2000倍以上,富集物经化学处理,光谱测定。测定下限∑RE7ppm,变异系数为10—25％,适用于99.999％氧化钆中14个稀土杂质元素的测定。     

2-乙基已基膦酸单(2-乙基已基)酯萃淋树脂分离-火花源质谱法测定高纯氧化钐中痕量稀土杂质

1引言火花源质谱法是测定高纯稀土的方法之一，具有灵敏度高、基体影响小、谱线干扰少等优点。对于单同位素的超高纯稀土元素，通常可以利用火花源质谱法直接测定，但对于99．9999％的超纯Sm3O3，由于Sm有7个同位素，晕轮背景干扰，谱线干扰以及大量基林元素存在，严重影响火花源质谱法灵敏地测定痕星稀土元素，必须分离富集，以P507萃林树脂为固定相、HCl-NH4Cl为淋洗液研究了大量基体Sm和其它14个痕量稀土杂质元素的分离方法，结合资合剂-活性碳柱富集淋洗液中14个痕量稀土元素，成功的建立了化学分离-火花源质谱法分析高纯氧化衫的方…     

高纯氧化钕中稀土杂质的化学光谱分析

本文采用P507萃淋树脂色谱法,盐酸为淋洗剂,偶氮胂Ⅲ柱上显色,对高纯氧化钕中稀土杂质进行分离富集。富集倍数为1000倍。富集物用干渣法光谱测定,测定下限∑RE为6ppm,变异系数 8—25％,可用于纯度为99.999％氧化钕中14个稀土杂质元素的测定。     

微型柱分离-ICP-MS法测定高纯氧化铽中14个稀土杂质元素

研究了微型柱分离 电感耦合等离子质谱法(ICP MS)测定高纯Tb4O7中痕量Lu的方法,采用Cyanex272负载树脂微型分离柱,选定了分离大量Tb4O7基体的实验条件,分离周期为40min。建立了微型柱分离Tb后测定Lu以及内标补偿法直接测定其它稀土杂质的高纯Tb4O7中14个稀土杂质元素的ICP MS分析方法。方法检出限为0.003～0.10μg g,加标回收率为86.6%～114%,相对标准偏差为1.1%～18%。方法可满足快速测定99.999%Tb4O7中14个稀土杂质元素的要求。     

高纯氧化铈中稀土元素杂质的测定

使用特效萃取剂P538分离氧化铈,用JY38P型等离子光谱仪进行稀土元素杂质的测定,杂质总量的测定下限为3.6ppm。研究了输出功率、分离效率及非稀土杂质对测定的影响。方法精密度为12％相对误差小于15％     

电感耦合等离子体质谱法测定高纯氧化钇中痕量稀土杂质的研究

描述了ＩＣＰ－ＭＳ法直接测定高纯氧化钇中痕量稀土杂质的研究。选择了工作参数，考察了各种干扰，采用铯为内标，直接测定了稀土杂质总量小于２μｇ／ｇ的高纯氧化钇样品，方法简便快速。     

ICP-AES法测定高纯氧化铕中稀土杂质元素

研究了锌粉还原 5709萃淋树脂分离富集 ICP AES法测定高纯氧化铕中14个稀土杂质元素的方法,用ICP AES法测定稀土元素工作曲线下限为(以氧化物计)镧为0.05mg·L-1,铈、镨、钇为0.25mg·L-1,钕、钐、铽、镝、钬为0.1mg·L-1,铒、铥、镱、镥、钇为0.05mg·L-1,回收率为90%～106%。方法简便、准确、快速,可用于99.99%氧化铕中14个稀土杂质元素的测定。     

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%.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.