电感耦合等离子体原子发射光谱法(ICP-AES)测定富铼渣中的铼

建立了电感耦合等离子体原子发射光谱法测定富铼渣中铼含量的方法。对样品的酸密闭消解、碱熔解和测定铼的条件进行了研究。结果表明:于盐酸(10%)介质、227.525nm分析线处,铼测定浓度在0.20~50.00μg/mL线性良好;两种样品分解方法测得铼结果吻合,用于富铼渣样品中1.85%~3.66%铼含量的测定,检出限、相对标准偏差(RSD,n=22)和加标回收率分别为酸密闭消解法6.46×10-10μg/mL,0.69%~1.1%和99.95%~100.1%,碱熔解法6.49×10-10μg/mL,0.69%~1.1%和99.96%~100.3%。     

火焰原子吸收光谱法测定铼产品中的痕量钠

建立了火焰原子吸收光谱法测定高铼酸、高铼酸铵、铼粉中痕量钠的方法,对样品的预处理和测定钠的条件进行了研究。结果表明:水溶解法、硝酸溶解法或硝酸-硫酸溶解法溶解样品完全,测得钠的结果吻合;于选定条件下,钠的测定浓度在0.020 0~0.500 0μg/mL范围内线性良好;测定高铼酸、高铼酸铵和铼粉样品中0.27~0.47mg/L、0.000047%~0.00048%和0.000040%~0.00049%的钠含量,检出限、相对标准偏差(RSD,n=7)、加标回收率分别为高铼酸3×10-4μg/mL、6%~10%、98%~102%,高铼酸铵3×10-4μg/mL、8%~9%、96%~102%和铼粉3×10-4μg/mL、5%~9%、96%~103%。方法结果准确、分析快速、操作简便,应用于实际的样品分析,结果满意。     

电感耦合等离子体质谱法测定铝钪合金中的稀土元素

通过酸溶快速分解铝钪合金,电感耦合等离子体质谱法(ICP-MS)测定铝钪合金中的La,Ce,Pr,Nd,Sm,Y,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu 15种稀土元素。对样品的前处理方式,仪器的工作条件,内标浓度等条件进行了考察。以103Rh,185Re作为内标校正铝的基体效应,考察了稀土元素的质谱干扰。在优化条件下各个元素的方法检出限为0.01~0.07μg/g,通过加标回收试验测得15个元素的回收率为96%~124%,相对标准偏差为0.74%~7.5%。     

电感耦合等离子体发射光谱法(ICP-AES)测定富铼渣中的铼

建立了电感耦合等离子体发射光谱法测定富铼渣中铼含量的方法。对样品的酸密闭消解、碱熔解和测定铼的条件进行了研究。结果表明：于盐酸(10%)介质、227.525 nm分析线处,铼测定浓度在0.20～50.00 μg/mL线性良好;两种样品分解方法测得铼结果吻合,用于富铼渣样品中1.85%～3.66%铼含量的测定,检出限、相对标准偏差(RSD,n=22)和加标回收率分别为酸密闭消解法6.46×10-10 μg/mL、0.69%～1.1%和99.95%～100.06%,碱熔解法6.49×10-10 μg/mL、0.69%～1.1%和99.96%～100.31%。     

电感耦合等离子体原子发射光谱法(ICP-OES)测定铍铀伴生矿石中的铍

建立了电感耦合等离子体原子发射光谱法(ICP-OES)测定铍铀伴生矿石中的铍的方法,研究了酸溶-碱熔融法溶样过程中加入的焦硫酸钾,对ICP-OES法测定铍铀伴生矿石中的铍含量产生的基体干扰问题。主要阐述消除基体干扰的一些措施。从实验数据可知,控制称样量、焦硫酸钾加入量、定容体积和加标稀释倍数,能够有效消除焦硫酸钾对ICP-OES法测定结果的基体干扰,6次平行测定结果的相对标准偏差为3.4%,加标回收率为98.7%~104.4%,实验表明,方法准确、可靠。     

电感耦合等离子体质谱(ICP-MS)法测定金绿宝石中16种痕量稀土元素

金绿宝石结构稳定,常规敞开酸溶、密闭酸溶、微波消解三种前处理方法并不能将其完全分解,测定结果偏低。本文采用碳酸钠-硼酸混合熔剂进行熔融,样品分解完全,建立了电感耦合等离子体质谱法(ICP-MS)测定金绿宝石中16种痕量稀土元素的分析方法。选择丰度高、干扰小的同位素、动能歧视碰撞池(KED)模式及干扰系数校正法消除质谱干扰,以185Re为内标元素及样品稀释降低基体干扰。实验表明：各稀土元素的校准曲线相关系数r值在0.9991~0.9998之间,方法检出限为0.0001~0.0134 μg/g,定量限为0.0005~0.0670 μg/g。采用国家标准物质GBW07151验证方法的精密度,计算出相对标准偏差(RSD, n=7)在1.3%~4.6%之间,并将此方法用于金绿宝石实际样品中稀土元素的测定,RSD为0.9%~3.2%,加标回收率为94%~104%,符合国家地质矿产行业标准,结果稳定、可靠。     

电感耦合等离子体质谱法测定土壤中痕量铀

建立电感耦合等离子体质谱法测定土壤样品中痕量铀含量的方法。采用硝酸、氢氟酸、高氯酸混合酸消解样品后,以铼为内标溶液校正基体干扰,用电感耦合等离子体质谱仪测定土壤中的痕量铀含量。实验结果表明,铀的质量浓度在0~20 ng/m L范围内与信号强度呈线性关系,相关系数r=0.999 9,方法检出限为0.006μg/g,测定结果的相对标准偏差小于5%(n=6),加标回收率在96%~103%之间。用该方法与标准方法对同一样品进行测定,两种方法测定结果一致。该方法准确可靠,满足土壤样品中痕量铀含量的测定要求。     

氧化镁烧结-电感耦合等离子质谱法测定冰铜中的铼

本文建立了一种利用电感耦合等离子体质谱法（ICP-MS）测定冰铜中铼的方法。样品经氧化镁烧结,热水浸取法处理,溶液经732强酸型阳离子交换树脂处理交换去除干扰离子,实现了ICP-MS直接测定冰铜中的铼。实验结果表明,在最佳试验条件下,方法的检出限可低至0.010mg/t,加标回收率为92.00%~104.00%,测定结果的相对标准偏差（RSD,n=7）小于5%,测定结果令人满意。由此可见,该方法精密度高,准确度高,可用于冰铜中铼的测定。     

电感耦合等离子体发射光谱法测定富铼渣中的铼

建立了电感耦合等离子体发射光谱法测定富铼渣中铼含量的方法。对样品的酸密闭消解、碱熔解和测定铼的条件进行了研究。结果表明：于10%盐酸介质、227.525 nm分析线,铼测定浓度在0.20～50.00 μg/ mL线性良好;两种样品分解方法测得铼结果吻合,用于富铼渣样品中1.85%～3.66%铼含量的测定,检出限、相对标准偏差(RSD,n=22)和回收率分别为酸密闭消解法6.46×10-10 μg/mL、0.689%～1.065%和99.95%～100.06%,碱熔解法6.49×10-10 μg/mL、0.691%～1.059%和99.96%～100.31%。     

电感耦合等离子体原子发射光谱(ICP-AES)法测定铅精矿中的锑

建立了电感耦合等离子体原子发射光谱(ICP-AES)法测定铅精矿中Sb元素的分析方法。实验中对难溶解的样品,确定了采用硝酸、硫酸、酒石酸溶样的方法,并选择了最佳工作条件。实验结果表明检出限为0.005μg/mL,加标回收率为99.0%~102%,相对标准偏差为1.5%~3.2%。该方法快速准确,适用于铅精矿难溶解样品中锑含量的测定。     

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.