化学光谱法测定6N氧化铈中14个稀土杂质元素

提出了二次分离富集－发射光谱法测定高纯氧化铈中１４个稀土杂质元素的方法。所建立的方法分离时间短，富集了倍数高，化学光谱测定下限为０．３３μｇ／ｇ，适用于６Ｎ的氧化铈中１４个稀土杂质元素的测定。     

XRF/EDTA滴定法测定钐铕钆富集物样品稀土总量

采用X射线荧光光谱(XRF)法测定钐铕钆富集物的平均摩尔质量;用EDTA滴定法测定钐铕钆富集物中的稀土总量。方法的标准偏差为0．13％,相对标准偏差为0．14％,所得结果与重量法结果基本一致。     

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）。     

还原-色层分离富集-光谱法测定荧光级氧化铕中的稀土杂质

发射光谱法直接测定纯Eu_2O_3中的稀土杂质,不能满足荧光级Eu_2O_3的分析要求,应对稀土杂质进行化学富集。铕可被还原为二价,较易与其他三价稀土分离。采用还原~-柱色层法,在封闭体系中进行分离,有效地避免二价铕的氧化而无需保护气氛。针对荧光     

高纯Eu2O3中稀土杂质的化学—X射线荧光光谱法测定

采用锌粉还原-P507萃淋树脂分离和富集高纯Eu_2O_3中的稀土杂质,用盐酸洗脱,NH_4OH沉淀、过滤制片后,用X射线荧光光谱法测定试样中14个稀土杂质。选择了该法制片和测定的各项条件。研究表明该法用基体铕作载体,省去了外加载体并简化了氧化物灼烧过程,且该法大部分稀土元素的测定下限为1μg,回收率为80～120％,变异系数优于14％。     

高纯氧化铕中微量稀土杂质的化学光谱测定

将高纯Ｅｕ２Ｏ２通过Ｐ５０７萃淋树脂分离富集，分离掉大量基体Ｅｕ２Ｏ３剩下微量稀土杂质用碳粉吸附，加ＫＢＨ４作载体进行光谱测定，本方法可测定９９．９９９９％，纯度的Ｅｕ２Ｏ３中微量稀土杂质。     

黑山热液型矿床稀土元素的地球化学行为

通过对岩石,矿石的稀土组成研究,揭示含矿热液稀土总旧为２．４８４－１１．７７８μｇ．ｇ＾－１,富集轻稀土型分布模式及铕,铈负异常。δＥｕ和δＣｅ表明从早至晚热液体系向氧化程度增加的方向演化。     

在线柱分离ICP-MS测定高纯Eu2O3中Tm

报道了一种在线柱分离ICP－MS快速测定高纯氧化铕中杂质铥的方法，采用一种新型膦酸类萃取剂，大大降低了林洗酸度，洗脱液中的Tm直接进入ICP－MS进行在线测定。整个分离测定周期为40min，方法检出限为0．12ng/mL，加示加收率为91．5％－98％，RSD为4．1％，该方法快速，简便。用于高纯氧化铕中杂质铥的测定，结果满意。     

离子交换纸搜集-X射线荧光光谱法测定高纯氧化铕中的轻稀土元素

X射线荧光光谱法不仅是测定常量稀土元素分量的一种行之有效的手段,而且对微量以至痕量稀土元素的测定也是可能的,尤其是测定轻稀土元素更为有效。若与化学分离相结合,其应用范围更加扩大,测定下限一般在ppm级,已有这方面的报导。本文以高纯氧化铕为分析对象,经离子交换分离后的轻稀土元素富集液,采用国产离子交换纸搜集制样,分别进行X射线荧光光谱测定,取得了良好的效果。     

双核双配体稀土配合物Tb1-xEux(TTA)3Phen的合成及光学性能研究

合成了系列铕铽双核稀土有机稀土配合物Tb1-xEux（TTA）3Phen，通过差热．热重分析、XRD、红外光谱、紫外光谱和荧光光谱等测试手段研究了配合物的组成、结构和发光性质。由紫外可见光谱可以看出，稀土有机配合物的吸收峰主要来自有机配体HTrA和1，10-Phen；差热-热重分析证明，稀土有机配合物热稳定性较好。荧光光谱和电致发光表明，铽对铕配合物的发光有协同作用。在该系列配合物中，不仅有机配体可以将吸收的能量传递给发光的铕离子使其发光，而且铽离子也可将其吸收的能量通过分子内能量传递给铕离子，增强铕的发光强度。同时就双核稀土有机配合物光致发光和电致发光的特性及掺杂体系的能量传递过程进行了讨论。     

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.     

关于"对‘燃料电池物理及化学性能的有限时间热力学分析方法'的讨论”答复

把有限时间热力学理论用于化学过程的研究,将会得到一系列新的结论,开展这方面的研究是很有意义的.文献[1]以燃料电池为例,在同时考虑化学反应及传热不可逆性的情况下,研究了燃料电池的性能界限,文献[2]指出了文献[1]计算化学反应及传热不可逆性而引起系统与有关环境的总熵产生率的错误以及由此而导致的结论所存在的问题,并进行了富有启发性的分析与讨论.但文献[2]对于系统与有关环境的总熵产生率的计算也是不正确的,由此得到的其它结论自然不能成立.本文将就此情况下系统与有关环境的总熵产生率的计算再次进行讨论,并给出电池功率和效率的有限时间热力学性能界限.