茶汤及河水中铁的形态分析

本文采用阳离子交换、活性炭分离－光度法研究了铁的形态分离及测定条件，建立了铁的形态分析方法。应用此法测定了茶汤及河水中铁的总量、悬浮态、溶解态、无机态、有机态、Ｆｅ（Ⅲ）和Ｆｅ（Ⅱ）等形态，结果令人满意。     

不同价态铬离子的毛细管电泳分离与测定

１引言由于元素的不同价态、不同存在形态具有不同的物理、化学性质与生理活性。如Ｃｒ（Ⅲ）是人体必需的元素，而Ｃｒ（Ⅵ）则是有害的。因此，离子的价态分析具有十分重要的意义。由于毛细管电泳可实现阴阳离子的同时分析，与离子色谱相比，具有简单、快速的特点。本文采用样品与ＥＤＴＡ络合的办法，用毛细管电泳在ＣＨ３ＣＯＯＮａ－ＣＨ３ＣＯＯＨ体系中（含电渗流改性剂和络合剂），对ＣｒＯ４２－、Ｃｒ３＋的分离测定进行了研究。用直接紫外法检测在５．５ｍｉｎ内可完成两种价态铬离子的测定，特别适于电镀废液或其它水质的分析。…     

富铬酵母中铬的化学种态及结合形态研究

对富铬酵母中铬的化学种态进行了分析和初步探讨。在铬的化学种态测定中铬的使用离子交换和火焰原子吸收法测定了富铬酵母中的Ｃｒ（Ⅲ）,方法快速简便、定量回收,结果表明,总铬呈为１５８２μｇ／ｇ的富铬酵母中,无机态铬占１６％,其中Ｃｒ（Ⅲ）为２３２μｇ／ｇ,Ｃｒ（Ⅵ）为２４．５μｇ／ｇ。酵各过程中的８４％以上的无机铬化合物转化成有机铬。说明铬参与了酵母细胞的生物合成,促进生物转化,对提高富铬酵母的生物疚极     

流动注射化学发光同时测定废水中的三价铬和六价铬

首次将镀铜锌粒作成优良的还原柱，在线还原Ｃｒ（Ⅵ）成Ｃｒ（Ⅲ），以鲁米诺－Ｈ２Ｏ２（ＫＢｒ）体系流动注射化学发光同时测定废水中两种价态的铬。分析速率为６０试样／ｈ；线性范围为１．０×１０＾－５－１．０×１０＾－９ｍｏｌ／Ｌ；测Ｃｒ（Ⅲ）及Ｃｒ（Ⅵ）的相对标准偏差（ｎ＝６）分别为０．３７％－４．０％及１．２％－４．４％；测定Ｃｒ（Ⅲ）的检出限２．３×１０＾－１１ｍｏｌ／Ｌ。测定结果与标准方法无显差     

流动注射在线富集分离—火焰原子吸收光谱法测定水体中的铬（Ⅲ）和铬（Ⅳ）

内装活性氧化铝（碱式）和阴离子交换树脂的微型柱流动注射在线富集分离水体中的铬（Ⅱ）和铬（Ⅳ），火焰原子吸收法直接检测，微型柱可同时富集两种价态的离子，分别用１ｍｏｌ／Ｌ的ＮＨ４ＮＯ３和ＨＮＯ３洗脱Ｃｒ（Ⅳ）和Ｃｒ（Ⅲ）于喷雾器中，进样时间２５ｓ，铬（Ⅳ）和铬（Ⅲ）的富集倍数分别为１１倍和２０倍，实际水样的加标回收率在９０％～１０６％之间，分析速率为５０个样／ｈ，铬（Ⅳ），铬（Ⅲ）的检出限（３δ）分     

纳米二氧化钛分离富集和ICP-AES测定水样中Cr(Ⅵ)/Cr(Ⅲ)

利用ＩＣＰ－ＡＥＳ研究了纳米ＴｉＯ２材料对Ｃｒ（Ⅵ）／Ｃｒ（Ⅲ）的吸附性能,并将其用于水样中铬的形态分析。结果表明,该法对１０ｍＬ试样测定Ｃｒ（Ⅵ）和Ｃｒ（Ⅲ）的检测限分别为６１ｎｇ／ｍＬ和４５ｎｇ／ｍＬ,其浓度在０．１～１０ｕｇ／ｍＬ范围内线性关系良好,５０倍量的Ｃｒ（Ⅵ）对Ｃｒ（Ⅲ）的检测不产生干扰。本法测定Ｃｒ（Ⅵ）和Ｃｒ（Ⅲ）的相对标准偏差分别为３．６％和４．２％（ｃ＝２．０ｕｇ／ｍＬ,ｎ     

巯基棉分离吸附溶出伏安法测定茶叶及茶汤中痕量砷

本文研究了巯基棉纤维（ＳＣＦ）对Ａｓ（Ⅲ）和Ａｓ（Ⅴ）的吸附性能，建立了ＳＣＦ分离Ａｓ（Ⅲ）和Ａｓ（Ⅴ）吸附溶出伏安法测定生物样品中痕量砷的方法。结果表明：在１ｍｏｌ／Ｌ盐酸介质中，ＳＣＦ可定量吸附Ａｓ（Ⅲ），Ａｓ（Ⅴ）不被吸附；用ＫＩ－（ＮＨ２）２ＣＳ预先还原Ａｓ（Ⅴ），通过ＳＣＦ分离，可消除干扰离子对测定砷的影响。方法用于测定桃叶、煤飞灰及番茄叶标样中的砷，其结果与标准值相符；应用此法还测定了几种茶叶及茶汤中的痕量砷和不同价态的砷，结果令人满意。     

固体表面化学发光分析 Ⅲ.超基性岩和钢中铬的微量测定

本文在不渗透阻挡滤纸上，用过氧化氢将Ｃｒ（Ⅵ）还原为Ｃｒ（Ⅲ），建立了Ｌｕｍｉｎｏｌ－Ｈ２Ｏ２－Ｃｒ（Ⅲ）体系的固体表面化学发光分析法。铬测定的线性范围为１．０～１０００ｎｇ，检测限为０．１３ｎｇ。与微量离子交换柱结合，快速测定了微量超基性岩和钢铁试样中的铬。     

湘江(长沙段)水中铬的形态分布及其迁移

研究了湘江水中铬的存在形态、分离方法和分析流程。用极谱催化法测定了江水中的总铬、总溶解铬、颗粒态铬、有机态铬、溶解无机铬、溶解无机态Cr(Ⅵ)、溶解无机态Cr(Ⅲ)。分析了不同季节里铬的存在形态及其迁移转化。结果表明溶解无机态铬是主要的存在形态,其中溶解无机态Cr(Ⅵ)较易转化成毒性较小的Cr(Ⅲ)。不同季节中铬的各形态的含量不同,其中颗粒态铬和有机态铬在夏季的含量较高,而其余各形态的铬在秋、冬两季的含量高于春、夏两季。江水对铬污染的自净能力较强,铬造成的污染的范围较小。     

流动分析法同时测定铬（Ⅵ）及铬（Ⅲ）过程中铈（Ⅳ）氧化剂的影响

以Ｃｅ（Ⅳ）为氧化剂，采用流动分析在线氧化技术，实现了对Ｃｒ（Ⅵ）和Ｃｒ（Ⅲ）的同时在线分析，发现Ｃｅ（Ⅳ）氧化剂在测定过程中产生负干扰，在而Ｃｒ（Ⅲ）存在时会使Ｃｒ（Ⅵ）的测定结果偏高，本文提出了一个校正模型，通过数学方法消除上述干扰，所建立的分析方法对Ｃｒ（Ⅵ）和Ｃｒ（Ⅲ）分析的平均相对误差不大于６．５％。     

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%.     

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.     

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.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.