抑制型离子色谱法测定白酒中的F-、Cl-、NO2-、H2 PO4-、NO3-

用抑制型离子色谱法测定白酒中的F^-、Cl^-、NO2^-、H2PO4^-、NO3^-。流动相为4mmol／LNa2CO3—3 mmol／LNaHCO3混合溶液,流速为1．5mL／min,进样量为0、5mL,在最佳色谱条件下,5种无机阴离子10min内实现基线分离。F^-、Cl^-、NO2^-、H2PO4^_、NO3^-的检出限分别为0、008、0．012、0、030、0．068、0．077mg／L。测定结果的相对标准偏差分别为1．86％、1．30％、2．06％、1．82％、1．50％,回收率分别为108．0％、94．0％、101．0％、98．7％、94．4％。     

两性化合物与离子对试剂的混合物作流动相的流动相离子色谱法测定气溶胶中水溶性阴离子

用流动相离子色谱法(MPIC),以两性化合物与离子对试剂的混合溶液为流动相,在C18柱上抑制电导检测分析气溶胶中常规无机阴离子和有机酸。实验采用氢氧化四丁基铵(TBAOH)为离子对试剂,与两性化合物3-(N-吗啉)-1-丙磺酸(MOPS)混合,加入Na2CO3无机添加剂作流动相,其浓度为1mmol／L TBAOH／5mmol／LMOPS／0．5mmol／LNa2CO3。分离柱采用硅质C18柱,抑制电导检测。可以较好地分离和检测常见的无机和有机阴离子。该方法具有较好的重现性和线性关系,F^-、Cl^-、NO2^-、Br^-、C3H3O3^-、NO3^-的回收率分别为102．0％、104．6％、102．4％、97．8％、97．75％和102．5％;检出限分别为0．017、0．014、0．0048、0．036、0．16和0．017mg／L。     

离子色谱法测定粮食鲜样中的硝酸盐含量

粮食鲜样经超声提取后，用离子色谱法测定浸提液中的硝酸盐。采用DX-100型离子色谱仪．以2．7mmol／L Na2CO3—0．3mmol／LNaHCO3的混合溶液作为淋洗液，流速为1．2mL／min，测定玉米、大豆、小麦中的NO3^-含量。NO3^-浓度在0．5—40．0mg／L范围内与色谱峰高呈良好的线性关系，相关系数r=0．9995，检出限为0．05mg／L，测定结果的相对标准偏差小于5％．加标回收率为96．0％-100．7％。     

整体柱离子对色谱对铬(Ⅵ)的快速测定

研究了基于硅胶整体柱的离子对色谱快速测定Cr（Ⅵ）的方法,讨论了淋洗液浓度、乙腈浓度、流速、温度和pH等因素对分离的影响。用1．0mmol／L四丁基氢氧化铵-0．8mmol／L邻苯二甲酸（pH6．0）作为淋洗液,流速6．0mL/min,可以在1min内快速分离测定Cl^-、NO3^-、Cr（Ⅵ）、SO4^2-离子。Cr（Ⅵ）的检出限为1．02mg／L,保留时间和峰面积的相对标准偏差（RSD）（n=5）分别为0．2％和0．3％。将方法应用于测定地下水中的Cr（Ⅵ）,回收率为104％。     

催化裂解富气吸收液的离子色谱法测定

以催化裂解富气吸收液为测定对象,建立吸收液中目标离子（包括NO2^-,NO3^-,SO4^2-）的离子色潜分析方法。在选定色谱柱的前提下,通过优化淋洗液浓度等色谱条件,实现了在大量干扰离子S^2-及与SO4^2-相邻的未知离子存在的三乙醇胺溶液中目标离子的定量。方法的检出限分别为NO2^- 62μg／L,NO3^- 26μg／L,SO4^2- 90μg/L,RSD值为0．73％～1．19％,加标回收率在91％～109％。     

柱后衍生-离子色谱法测定面粉中痕龄逅嵫蔚难芯

采用离子交换柱后衍生离子色谱法测定面粉中痕量溴酸盐的含量。选用高容量柱,以9．0mmol／L Na2CO3溶液为流动相,邻二甲氧基联苯胺盐酸盐（ODA）等为柱后衍生剂,在450nm波长处检测。样品处理包括溶剂溶解、超声浸提、沉淀离心、过滤分离等步骤,BrO3^-的检出限为0．033μg/L（3σ）,线性范围为0．2～260μg／L,样品分析结果的相对标准偏差（RSI））小于2％（n=6）,加标回收率在92％～101％之间。共存离子F^-、Cl^-、Br^-、NO3^-、NO2^-、PO4^3-、SO4^2-以及苯甲酸、山梨酸、甜蜜素、糖精钠、柠檬酸、酒石酸等食品添加剂均对测定无干扰。     

离子色谱法测定生活饮用水中4种阴离子

对离子色谱法测定饮用水中的F-,C1-,NO3- -N,SO4^2--4种阴离子的分析方法进行了优化。用正交试验法选择最优实验条件为：流速0．9mL／min,柱温32℃。4种阴离子检出限：F-0．02mg／L,Cl-0．04mg／L,NO3--N0．04mg／L,SO4^2- 0．16mg／L。测定结果相对标准偏差均小于5％,回收率为91.3％～106．1％,相关系数大于0．999。该方法操作简便,灵敏度、准确度高,标准工作曲线线性良好,可用于饮用水中F-,C1-,NO3^- —N,SO4^2—4种离子的同时分析。     

离子色谱法分析保险粉工业回收甲酸钠中的阴离子

利用单柱阴离子交换色谱法测定了保险粉工业回收产品中的甲酸,Cl－,SO,NO,羟乙基硫代硫酸盐,SO和S2O。以1．8mmol／L邻苯二甲酸和1．35mmol／L三羟甲基氨基甲烷的混合溶液作淋洗液,流速为1．0mL／min时,分离效果良好。7种离子的加标回收率在96％～102％之间,检测下限在0．2～5mg／L之间,方法准确、简便。     

离子色谱法同时测定叶菜中的硝酸盐和亚硝酸盐

采用抑制型离子色谱法同时测定叶菜中的硝酸盐和亚硝酸盐的含量。色谱柱为Ionpac AS11柱，流动相为21mmol/L NaOH溶液，检测器为电导检测器（CD），流动相流速为1.0mL/min。该方法简便、快捷，准确度和灵敏度高，NO2^-和NO3^-的回收率分别为97％－105％和95％－104％，相对标准偏差RSD＜5．0％。同时考察了样品浸提时间对结果的影响。     

离子色谱法测定啤酒中的F^-、C1^-、SO4^2-、NO3^-和PO4^3-

建立了以AS11—HC型阴离子交换柱分离、NaOH溶液为淋洗液、甲醇为有机改进剂、化学抑制电导检测测定啤酒中的F^-、C1^-、SO4^2-、NO3^-和PO4^3-?A的离子色谱方法。各被测离子的线性关系良好，相关系数为0．9778～0．9991．测定结果的相对标准偏差为0．02％～3．60％，样品回收率为97．88％～103．80％。     

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.