高效液相色谱法同时测定土壤中毒死蜱残留及其有毒代谢物3,5,6-TCP

通过对色谱分离条件优化、提取体系建立和固相色谱小柱筛选,建立了用弗罗里硅土固相萃取小柱净化高效液相色谱法同时测定土壤中毒死蜱农药残留及其有毒代谢物3,5,6-TCP.方法加标回收率在59％～87％之间,检测限为0.0005～0.03 μg/g,日内回收率标准偏差RSD≤4.3％,日间回收率标准偏差RSD≤4.9％,方法...     

超声提取-气相色谱法测定保健品中15种有机氯农药残留量

保健品样品经丙酮、二氯甲烷、石油醚超声提取,提取液过弗罗里硅藻土层析柱净化,所得经净化的淋出液中15种有机氯农药残留量用于气相色谱法测定。采用OV-1701石英毛细管色谱柱分离,用电子捕获检测器测定。15种化合物的检出限(3S/N)在0.091～0.621ng.kg-1之间。在3个浓度水平下加入标准溶液进行了回收和精密度试验,所得回收率在80.5%～126%之间;测定值的相对标准偏差(n=6)在1.2%～13%之间。     

微波萃取-全自动凝胶色谱净化-气相色谱法同时测定太湖沉积物中多氯联苯和有机氯

建立了沉积物中多氯联苯和有机氯农药等39种持久性有机污染物的同时测定方法。样品用正己烷和丙酮(体积比为1∶1)进行微波提取,提取溶液经凝胶色谱和弗罗里硅土净化,浓缩后采用气相色谱法测定。回收率在68.8%~84.2%,检出限为0.05~0.25ng/g。方法适用于沉积物样品中多种多氯联苯和有机氯农药含量的同时测定。     

基质固相分散-反相液相色谱法测定蔬菜中二甲戊乐灵农药残留

应用基质固相分散-反相液相色谱技术建立了提取、检测蔬菜中二甲戊乐灵农药残留的分析方法。研究了提取及测定条件对检测二甲戊乐灵的影响,确定了最佳提取条件:萃取吸附剂为弗罗里硅土,样品与弗罗里硅土吸附剂的比例为1∶4,洗脱剂为20 mL乙酸乙酯。二甲戊乐灵的测定线性范围为0.02~2.0 mg/L、r0.999。应用此方法测定了某些蔬菜样品中二甲戊乐灵农药残留,测定相对标准偏差为2.2%~5.2%。在几种蔬菜中的加标回收率为85%~93%,当样品为0.5 g时,方法检出限在5.5~10 ng范围内。     

固相萃取/气相色谱-串联质谱法测定竹笋产地土壤中42种持久性有机污染物

建立了同时测定竹笋产地土壤中8种多环芳烃(PAHs)、18种多氯联苯(PCBs)和16种有机氯农药(OCPs)的方法。样品经丙酮-正己烷(1∶1,体积比)大功率超声提取,复合弗罗里硅土柱固相萃取净化、氮吹浓缩后,利用气相色谱-三重四极杆质谱(GC-MS/MS)测定。结果表明,42种持久性有机污染物(POPs)在35 min内得到分离,在2. 0～2 000. 0μg/L范围内线性关系良好,相关系数(r2)为0. 995 2～0. 999 8;方法的加标回收率为62. 3%～128%,相对标准偏差(RSD)为0. 5%～15. 8%,检出限(S/N=3)为0. 070～6. 902μg/kg。该法操作简便,准确度好,灵敏度高,可用于竹笋产地土壤样品中42种POPs的同时测定。     

固相萃取气相色谱法测定水果中克菌丹和灭菌丹

采用硅镁吸附剂和硅胶作为混合固相萃取的净化方法,建立了固相萃取气相色谱法同时测定水果中克菌丹和灭菌丹的分析方法。研究了多种固相萃取柱和不同洗脱溶剂对克菌丹和灭菌丹保留行为的影响,优化了固相萃取净化方法及样品提取方法的分析条件。用GC-ECD检测,两种农药在0.05～2.0mg/L浓度范围内呈线性关系,相关系数大于0.997。苹果中4个浓度克菌丹和灭菌丹的加标回收率分别在100%～111%和104%～113%之间,RSD在3.0%～7.2%和2.8%～4.2%之间。在菠萝、草莓、梨和橙子中,克菌丹的平均回收率和RSD分别在95.6%～112%和2.5%～7.5%之间;灭菌丹在82.5%～96.4%和3.3%～8.0%之间,克菌丹和灭菌丹的方法检出限分别为0.012mg/kg和0.0056mg/kg。     

毛细管气相色谱法测定烟草及烟气中有机氯农药残留量

烟草样品或从卷烟烟气中收集到的固态悬浮颗粒样品以正己烷在索氏提取器中提取,提取液用弗罗里硅土固相萃取净化,所得溶液经蒸缩至5mL后,供气相色谱法测定。采用DB-5弹性石英毛细管柱分离样品,电子捕获检测器检测,共测定了17种有机氯农药(OCP′s),其检出限(3S/N)在0.02～0.10μg.g-1范围内。平均加标回收率为86%～92%,相对标准偏差(n=7)为3.0%～4.1%。     

微波辅助萃取法测定烟草中有机氯类农药残留量

建立了一种微波辅助萃取-固相萃取净化测定烟草中17种有机氯类农药残留量的新方法. 样品用V(正己烷):V(乙酸乙酯)＝1:1提取, 提取液经Florisil固相萃取柱净化后, 采用气相色谱-电子捕获检测器(GC-μECD)进行检测. 17种有机氯农药的0.01、 0.05 mg/kg和0.5 mg/kg加标回收率均在82%以上, RSD在0.11%～8.2%之间, 能满足当前烟草中有机氯农药残留的检测要求.     

毛细管气相色谱法测定水果、蔬菜中17种有机氯农药的残留量

采用毛细管气相色谱法测定水果、蔬菜中17种有机氯农药的残留量。用丙酮-正己烷混合液(1：1)提取样品中的有机氯农药,将提取液浓缩后,经过弗罗里硅土层析柱净化,用HP-5毛细管柱分离,再以电子捕获检测器测定,外标法定量。方法的加标回收率为80．7％-113．1％,测定结果的相对标准偏差为9％-17％,检出限为0．5—8．0ng／g。     

毛细管气相色谱法测定芝麻中多种有机磷农药残留量

建立了芝麻中多种有机磷农药残留量的毛细管气相色谱的测定方法。样品以V(乙腈 )∶V(丙酮 ) =1 0∶1混合溶剂为提取剂 ,应用超声波辅助提取 ,固相吸附层析柱净化m(中性氧化铝 )∶m(弗罗里硅土 ) =1∶1 ,采用GC FPD法同时测定芝麻中的多种有机磷农药残留量。检出限为 0 .0 1 1～ 0 .0 1 7μg mL。方法的回收率为 82 .1 %～ 1 0 9.7%。     

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.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.