电感耦合等离子体原子发射光谱（ICP-AES）法测定铜阳极泥中的金含量

实验采用某铜冶炼生产企业的铜阳极泥样品,对其中的金含量进行测定。用王水溶解样品,王水(3%)定容至100 mL容量瓶中,用电感耦合等离子体原子发射光谱法测定。实验表明,选择Au242.795nm为分析谱线,方法检出限为(n=11)0.09μg/mL,测定下限为0.27μg/mL,加标回收率在97%～107%,线性相关系数为0.999 928,分析结果满足要求。     

王水回流溶样-火焰原子吸收光谱法测定地质样品中的金

建立王水回流溶样聚氨酯泡沫塑料吸附火焰原子吸收光谱法测定地质样品中金的分析方法。在传统法使用锥形瓶王水溶样的基础上,在磨口锥形瓶上增加回流装置,以长15 cm的玻璃管作为冷却回流管,加入30mL王水溶液(1+1)对样品进行消解,采用火焰原子吸收光谱法测定。金的质量浓度在0～4.00μg/mL范围内与吸光度呈良好的线性关系,相关系数为0.999 3,检出限为0.058μg/mL。金矿石标准物质测定结果的相对标准偏差为2.75～6.41%(n=6),相对误差为–5.00%～0.61%;5种不同矿区金矿石样品测定结果的相对标准偏差为2.02%～9.24%(n=9)。该方法样品消解完全,减少了王水的使用量和氮氧化物的排放,操作简便,结果准确可靠,适用于地质样品的批量分析。     

王水溶样-电感耦合等离子体质谱（ICP-MS）法测定地质样品中的金

称取10.00 g样品放于马弗炉中700℃条件下焙烧后,加入约60 mL王水,盖上表面皿于低温电热板(1000 W)溶解40 min,加入5 mL动物胶(20 g/L),搅拌均匀后加入等体积的水,抽滤,滤液定溶至500 mL,分液后以10 ng/mL的Rh为内标建立了王水溶样-电感耦合等离子体质谱(ICP-MS)法快速测定地质样品中金的分析方法。方法适用于检测0.1~10μg/g品位的矿石样品,对国家一级标准物质GBW07209、GBW07808、GBW07809、GBW07300进行12次测定,其相对标准偏差RSD均小于5%,相对误差RE均小于2%。方法具有简单快速等优势,在实际应用中得到满意的结果。     

离子交换分离石墨炉原子吸收光谱法测定高纯铟中痕量铜

高纯铟样品经盐酸溶解、以阳离子交换树脂分离出痕量铜后,用石墨炉原子吸收光谱法测定铜。研究了溶样方法、离子交换分离和测定铜的条件:用8mL浓盐酸将1g样品溶解;以0.6mol/L盐酸作为淋洗液进行离子交换,可把绝大部分铟基体及样品中痕量的银、砷、镉、硅分离除去,随后用2.0mol/L盐酸把铜洗出并收集之。铝、铁、镁、镍、铅、锡、铊、锌与小于10μg的铟不能与铜分离,但对测定无影响。当称样量为1g,进样量为50μL时,方法线性范围为1~4ng/mL,检出限为0.1ng/mL,测定下限为0.001μg/g,比行业标准方法 YS/T 230.1—2011的0.1μg/g低两个数量级。方法用于实际样品分析,结果与电感耦合等离子体质谱法(ICP-MS)相符,相对标准偏差(RSD,n=8)为1.7%~18.5%,加标回收率为94.8%~115.0%。     

电感耦合等离子体发射光谱法测定不锈钢中的铬、镍、锰、铜、钛、铝

建立电感耦合等离子体发射光谱仪同时测定不锈钢中铬、镍、锰、铜、钛、铝6种元素含量的方法。用20mL王水溶解样品,铬、镍、锰、铜、钛、铝的分析谱线分别为283.563,231.604,259.373,324.754,334.941,308.215 nm。铬、镍、锰、铜、钛、铝的质量浓度与其信号强度均呈良好的线性关系,线性相关系数均不小于0.999,检出限分别为0.007,0.009,0.002,0.007,0.002,0.008μg/mL。测定结果的相对标准偏差为0.17%～2.80%(n=6),加标回收率为96.50%～103.70%。用该法测定国家标准物质,测定值与标准值一致,相对误差为0.05%～3.03%。该方法准确、可靠,可用于不锈钢中铬、镍、锰、铜、钛、铝的测定。     

火焰原子吸收光谱法测定硒碲混合物中的碲

建立了酒石酸-硝酸-盐酸混酸溶解样品,在王水-酒石酸介质中,采用空气-乙炔火焰在原子吸收光谱仪上测定硒碲混合物中碲的方法。研究了样品处理方法、乙炔流量、燃烧高度、灯电流、溶液介质等有关工作条件。实验表明碲浓度在1～20μg/mL范围内与吸光度呈良好的线性关系,回归方程为A=0.0229C+0.0009,相关系数0.9998,检出限0.08μg/mL。适合于硒碲混合物中碲的测定,相对标准偏差为0.9%～1.3%,回收率为98%～102%。     

原子荧光光谱法测定铜合金中铋元素含量方法改进

基于原子荧光光谱法测定铋元素时检出限低、测定结果稳定且准确等优点,研究原子荧光光谱法测定铜合金中铋元素含量的方法。在标准系列中加入相近浓度的铜元素标准溶液,原子荧光光谱法测定铜合金中铋元素含量。称取0.1 g样品,加入10 mL硝酸溶解,10%硫脲-5%抗坏血酸溶液7.5 mL预处理样品。在20μg/L的铋标准溶液中加入6 mL浓度为1000μg/mL的铜元素标准溶液。结果表明:在0~20μg/L范围内,该方法线性关系良好,线性方程为I=138.1670c+43.8572,相关系数为0.9996,所测定的样品中铋元素含量的相对误差在-4.3%~7.7%之间,精密度在0.4%~4.7%之间。原子荧光光谱法可作为铜合金中铋元素含量测定的方法。     

王水溶样-电感耦合等离子体质谱（ICP-MS）法测定地质样品中的金

称取10.00g样品放于马弗炉中700℃条件下焙烧后,加入约60mL王水,盖上表面皿于低温电热板(1 000W)溶解40min,加入5mL动物胶(20g/L),搅拌均匀后加入等体积的水,抽滤,滤液定溶至500mL,分液后以10ng/mL的Rh为内标建立了王水溶样-电感耦合等离子体质谱(ICP-MS)法快速测定地质样品中金的分析方法。方法适用于检测0.1～10μg/g品位的矿石样品,对国家一级标准物质GBW07209、GBW07808、GBW07809、GBW07300进行12次测定,其相对标准偏差RSD均小于5%,相对误差RE均小于2%。方法具有简单快速等优势,在实际应用中得到满意的结果。     

王水溶样-电感耦合等离子体质谱（ICP-MS）法测定地质样品中的金

称取10.00g样品放于马弗炉中700℃条件下焙烧后,加入约60mL王水,盖上表面皿于低温电热板(1 000W)溶解40min,加入5mL动物胶(20g/L),搅拌均匀后加入等体积的水,抽滤,滤液定溶至500mL,分液后以10ng/mL的Rh为内标建立了王水溶样-电感耦合等离子体质谱(ICP-MS)法快速测定地质样品中金的分析方法。方法适用于检测0.1～10μg/g品位的矿石样品,对国家一级标准物质GBW07209、GBW07808、GBW07809、GBW07300进行12次测定,其相对标准偏差RSD均小于5%,相对误差RE均小于2%。方法具有简单快速等优势,在实际应用中得到满意的结果。     

逆王水微波消解–电感耦合等离子体质谱法测定地球化学样品中的碘和溴

地球化学样品经微波辅助逆王水消解后,在氨性介质中采用电感耦合等离子体质谱法快速测定碘和溴的含量。取样量为0.1 g,逆王水的用量为1.6 mL,对样品进行程序化微波消解,通过在线加入内标校正基体效应和信号漂移对测定所造成的影响。碘、溴的检出限分别0.15,0.21μg/g,测定结果的相对标准偏差不大于5.0%(n=7),国家标准样品测定值与标示值相符。该方法在样品消解后加入定量氨水可直接分析,减小了碘测定的记忆效应,提高了分析速度,可应用于地球化学样品中碘和溴含量的测定。     

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.