离子色谱-电感耦合等离子体质谱联用研究尿中碘和钼形态

建立离子色谱-电感耦合等离子体质谱(IC-ICP-MS)联用测定人尿中碘和钼形态的方法,该方法对IO3-和I-检出限分别为0.1 ng/mL和0.2 ng/mL,对MoO42-(以Mo计)的检出限为0.4 ng/mL,IO3-(以I计)、I-和MoO42-(以Mo计)线性回归系数r均大于0.999。检测实际尿样中I-和MoO42-(以Mo计)相对标准偏差RSD均小于5%,实际尿样中未发现IO3-。尿样中I-和MoO42-(以Mo计)的加标回收试验表明其回收率在91%～102%之间。本文利用尺寸排阻色谱-电感耦合等离子体质谱(SEC-ICP-MS)联用首次直接证明人尿中还存在至少3种形态有机碘以及1种形态有机钼。     

高效液相色谱-电感耦合等离子体质谱法快速测定天然水中无机砷的形态

建立了高效液相色谱-电感耦合等离子体质谱联用技术快速测定天然水中无机As形态的分析方法。采用Capcell PAK C18色谱柱分离As3+和As5+,5 min内可完成色谱分离,缩短了分析时间。在优化条件下,方法检出限可达到0.11μg/L和0.12μg/L,可满足天然水样品中无机砷形态的分析要求。研究了As形态标准溶液在不同保存条件下的形态稳定性问题,确定了无机As形态工作标准溶液和野外天然水样品采集和保存的最佳条件和时间。     

反相离子对高效液相色谱法测定微量碘的研究

建立了一种反相离子对高效液相色谱测定微量碘的新方法。采用WatersSpherisorbODS2(5μm ,4.6mmi.d.×250mm)色谱柱 ,以甲醇 -水 (体积比为30∶70)作为流动相 ,四丁基溴化铵 (TBA·Br)作离子对试剂 ,流速为1.0mL/min,在223nm处检测 ,将I- 与在紫外区有吸收的共存离子完全分离。I- 的质量浓度在0.20～180μg/mL范围内 ,峰面积Y与质量浓度X(μg/mL)呈良好的线性关系 ,r=0.9997 ,I -的检出限为53.2μg/L。该方法已用于海水和海带、紫菜等食品中碘含量的测定 ,加标回收率为98%～101 % ,相对标准偏差为1.04 %～3.01 %。     

苯胺蓝增色光度法测定食盐中的碘

在H2SO4介质中,KIO3与苯胺蓝反应增色程度与IO3-量在一定范围内呈线性关系,从而建立了增色光度法测定碘的新方法.实验结果表明,该体系最大吸收波长为603 nm,IO3-在0.91～4.55 μg/L范围内符合比耳定律,表观摩尔吸光系数为5.00×105 L·mol-1·cm-1.本法可直接测定食盐中的碘.     

2′,7′-二氯荧光素荧光光谱法测定食盐中的IO-3含量

在pH 1.4~3.4的H2SO4介质中,IO3-与过量I-反应生成I2,I2与2,′7′-二氯荧光素反应,引起荧光猝灭,体系荧光强度降低,由此建立了荧光光谱法测定食盐中IO3-含量的新方法。体系的荧光发射波长λem=515 nm,体系的荧光强度降低值△IF与IO3-含量在0.40~2.00μg.mL-1之间呈良好的线性关系,回归方程为△IF=12.675ρ-3.499(ρ的单位μg.mL-1),相关系数r=0.998 0。该法灵敏度高,选择性好,用于食盐中IO3-的含量的测定,结果满意。     

阻抑动力学光度法测定乳品中的痕量碘

研究了在稀H2SO4介质中,痕量I-对KBrO3氧化酸性品红的阻抑作用及其动力学条件,建立了测定痕量I-的阻抑动力学光度分析的新方法.测定I-的线性范围为0～0.04 μg/mL,检出限为1.1×10-9 g/mL.已用于乳品中痕量碘的测定.     

痕量碘的四元碱流动注射分光光度法研究粮食中微量碘的测定

本文报道了基于Feigl点滴反应的痕量碘的流动注射分光光度测定方法。在痕量碘存在下,无色氯胺T和四元碱(N,N-四甲基对苯二胺)在醋酸盐介质中发生反应,反应30s时在605nm下测定其蓝色产物的吸光度。在90样/h的采样频率下检出限为0.2μg/L(3σ)。对10μg/L碘标准溶液测定的变异系数为0.6%(n=11)。粮食灰分液中加入5μg/L碘的回收率较好。     

盐酸氯丙嗪显色-分光光度法快速测定食盐中的碘含量

研究了在硫酸介质中,IO3-能与盐酸氯丙嗪发生氧化显色反应,且显色的程度和IO3-的量成正比例关系,据此建立了分光光度法测定食盐中碘含量的分析方法。显色物质的最大吸收波长为526nm,线性回归方程为y=1.214x+0.011 8,相关系数为0.998 9,表观摩尔吸光系数为5.2×104 L/(mol·cm),碘浓度在0~24μg/10mL范围内有良好的线性关系,相对标准偏差为1.2%~2.2%,加标回收率为97.5%~102.0%,实验表明,方法操作简单,灵敏度高、选择性好,适用于食盐中碘含量的测定。     

应用IC-ICP-MS测定胶州湾表层沉积物中的溴酸盐、碘酸盐及亚硒酸盐

建立了离子色谱-电感耦合等离子体质谱联用技术(IC-ICP-MS)测定溴酸盐、碘酸盐及亚硒酸盐的分析方法。该方法对0～1000μg/kg范围内BrO3-、IO3-、SeO23-的线性关系良好(r2=0.9995～0.9999),检出限分别为0.05、0.08、8.15μg/kg;加标回收率为78%～105%;选取经过前处理的BrO3-、IO3-、SeO32-含量分别为85.14、7.20、55.15μg/kg的样品,连续测试7次,其相对标准偏差(RSD)分别为2.5%、1.8%、2.3%。利用该方法初步测定了胶州湾表层沉积物中3种离子形态的含量。结果显示,胶州湾所选8个站位中均检出了3种离子,其中BrO3-含量最高,达2755.58μg/kg,SeO32-次之,IO3-含量最低;BrO3-和SeO23-呈现由西南向东北递增的趋势,离岸低,近岸高,IO3-则呈由中心向南北两侧递减的趋势。该方法具有杂质干扰小、分析速度快、灵敏度高等特点,适用于沉积物中BrO3-、IO3-以及SeO32-的定性定量分析。     

离子色谱法测定饱和卤水中痕量碘离子

建立了一种在线样品预处理、脉冲安培检测饱和卤水中痕量I-的离子色谱新方法。进样体积为50μL,选用Cryptand C1浓缩柱富集I-,并用10 mmol/L NaOH洗脱样品中的基体Cl-。用0.5 mmol/L NaOH将I-从浓缩柱转移到保护柱柱端。用IonPac AS20阴离子交换柱,25 mmol/L NaOH淋洗分离,结合脉冲安培银工作电极检测。I-检出限为0.07μg/L(3倍基线噪音);I-在5~1000μg/L范围内具有良好的线性关系(r=0.9995)。50μg/L的I-溶液连续进样9次,峰高相对标准偏差(RSD)为1.0%。     

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.     

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.     

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.     

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.