固载硫杂杯芳烃树脂分离富集-火焰原子吸收法测定痕置银

报道了色谱301固载硫杂杯芳烃树脂分离预富集-火焰原子吸收光谱法测定痕量银的新方法。探讨了固载硫杂杯芳烃树脂对银的吸附原理与最佳条件。将含Ag^＋试液在pH=10、温度为23±2℃的条件下恒温震荡10min，静置10min，Ag^＋可被树脂定量富集被吸附的Ag^＋可用5mL酸性硫脲（0．15mol／L HCl＋0．15mol／L硫脲）完全洗脱，洗脱液中的银用火焰原子吸收光谱法测定。该法对银的检出限为0．17μg／L（3σ，n=11）；线性范围为0．006—3mg／L。对0．18mg／L的Ag^＋标液进行7次测定，RSD=1．53％。回收率在99．9％-105．0％之间。用于“二次资源”锌矿渣和环境水样中痕量银的测定，结果满意。     

流动注射在线三正辛胺萃淋树脂分离富集火焰原子吸收法测定银

使用填充三正辛胺（TOA）萃淋树脂的微型柱，采用流动注射在线分离富集与火焰子吸收法联用技术，对微量银的测定进行了研究。在1．0mol/L HCl介质中样品流速为8．1mL/min，采样60s，以0．25mol/L HCl-0.5mol/L硫脲洗脱。在30样／h的分析速度下，富集倍率为26倍，富集效率为26／min，消耗指数为0．31mL。线性范围为0－1000μg/L，检出限为1．2μg/L。银含量为50μg／L时，连续11次测定的相对标准偏差为1．4％。对铅锌冶炼矿渣样液进行加标回收率试验，回收率为91．1％－100．6％，并应用于测定光谱纯氧化镁中的微量银。     

痕量铊的液膜分离富集与测定

以正十六胺-L113B-煤油为膜相，内相为0．040mol／L的NaOH溶液；外相为0．040mol／L的KCl和0．060mol／L的HCl溶液对痕量铊进行分离富集。实验结果表明，Tl(Ⅲ)的迁移率达99．5％以上。在合适的条件下，可与其它离子分离。此法可用于黄铁矿样品中微量铊的分离富集，以火焰原子吸收光谱法测定，回收率在99％以上。本文还对Tl(Ⅲ)的液膜富集机理进行了讨论。     

三正辛胺萃淋树脂的合成及对银分离富集的研究

报道了Levextrel型三正辛胺（TOA）萃淋树脂的合成方法及对银分离富集的研究，用新合成的萃淋树脂，铅锌冶炼矿渣中的银在1mol/L的盐酸介质中定量吸附后可用0．25mol/L NH4Cl-0.5mol/L硫脲洗脱，以火焰原子吸收光谱法测定，其回收率为99．4％－104．3％。此树脂对浓度低至0．5μg/mL的银亦可富集和定量回收，并有较长的使用寿命。     

PVC-PP树脂分离富集/火焰原子吸收光谱法测定海水中痕量铜镍钴

采用自制的聚氯乙烯多乙烯多胺（PVC-PP）树脂,在pH值为5．0的条件下,分离富集海水中的痕量铜、镍、钴,以1．2mol／L盐酸溶液洗脱．火焰原子吸收光潜法测定,富集倍数最大可达100倍（回收率大于90％）。研究了吸附与洗脱的最佳条件,方法检出限分别为铜0．81μg/L、镍0．98μg/L、钴0．57μg/L（富集倍数100,S／N=3）,相对标准偏差小于5％（n=7）,样品加标回收率在90％-105％之间。     

固载硫杂杯芳烃树脂分离富集-火焰原子吸收法测定痕量银

报道了色谱301固载硫杂杯芳烃树脂分离预富集-火焰原子吸收光谱法测定痕量银的新方法。探讨了固载硫杂杯芳烃树脂对银的吸附原理与最佳条件。将含Ag 试液在pH=10、温度为23±2℃的条件下恒温震荡10min,静置10min,Ag 可被树脂定量富集被吸附的Ag 可用5mL酸性硫脲(0.15mol/LHCl 0.15mol/L硫脲)完全洗脱,洗脱液中的银用火焰原子吸收光谱法测定。该法对银的检出限为0.17μg/L(3σ,n=11);线性范围为0.006~3mg/L。对0.18mg/L的Ag 标液进行7次测定,RSD=1.53%,回收率在99.9%~105.0%之间。用于“二次资源”锌矿渣和环境水样中痕量银的测定,结果满意。     

三聚氰胺-甲醛-三乙烯四胺树脂的合成及其对痕量银的吸附性能研究与应用

以甲醛为交联剂,以三聚氰胺、三乙烯四胺为原料合成了一种新型的三聚氰胺-甲醛-三乙烯四胺(MF-TETA)分离树脂,研究了MF-TETA分离树脂对痕量银的分离富集性能,探讨了MF-TETA分离树脂对银的吸附原理与最佳条件。在pH6.0、温度为35℃的条件下,试液中的银可被MF-TETA树脂定量吸附,其静态饱和吸附容量为32 mg/g,吸附在树脂上的银可用10 mL0.05 mol/L HNO3完全洗脱,洗脱液中的银用火焰原子吸收光谱法(FAAS)测定。该法对银的检出限为16 ng/mL(3σ,n=11),线性范围为0.05~5mg/mL,RSD=2.2%,回收率在95.8%~102.0%之间,方法可用于中草药中痕量银的测定。     

PE(聚乙烯)-双硫腙复膜树脂分离富集原子吸收法测定地质样品中的钯

研究了PE(聚乙烯) 双硫腙复膜树脂的合成及其分离富集样品中钯的条件。于pH2.0的HCl介质中,钯定量吸附在PE(聚乙烯)-双硫腙复膜树脂上,用100g L乙二胺-20g LNaOH溶液洗脱,火焰原子吸收光谱法测定。回收率在94.5%～101%之间。可用于实际地质样品中贵金属的分离富集与测定。     

地质样品中金银的连续快速测定——二苯硫脲-三正辛胺棉富集分离液珠萃取比色法

采用二苯硫脲(DPTU)—三正辛胺(TNOA)棉富集分离金、银已有报道。本文采用该吸附剂制备了DPTU—TNOA棉吸附柱,并研究了动态法富集分离金、银的条件。研究表明.吸附柱富集金、银的最佳酸度(体积分数)为5％～20％王水。当含金溶液以1～6ml·min~(-1)流速通过0.1g吸附剂制备的吸附柱时,金、银的吸附率均在98％以上。采用硫代米蚩酮(TMK)液珠萃取比色法连续测定了地质样品中的金、银。方法的检出限为0.5×10~(-9),银为5×10~(-9)。经样品验证,其分析结果满足化探找金工作的需要。     

甲基膦酸二甲庚酯萃取色谱法分离金、铂的研究

本文研究了以4.0mol/L H_2SO_4-0.50mol/L MgSO_4 为流动相,以硅烷化硅球负载的甲基膦酸二甲庚酯(P350)作固定相。萃取色谱法使微量铂、金与常见贱金属分离,富集在色谱柱上的铂和金分别用0.10mol/L HCl和1.0％Na_2SO_2溶液洗脱进行连续分离与测定。经实际样品的试用考核,结果令人满意。     

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.