在阴离子表面活性剂存在下,漂蓝6B分光光度测定矿石中的微量铍

漂蓝6B(ECAB)是一种有实用价值的显色剂。十二烷基硫酸钠(SDS)对吡啶偶氮衍生物与某些金属离子体系有强烈的增敏作用,但阴离子表面活性剂对三苯甲烷酸性染料与金属离子的络合物体系的增敏作用尚未见报导。本文研究了SDS对三苯甲烷类酸性染料之一——ECAB与铍络合物体系的增溶增敏作用。结果表明,在SDS存在下,在pH6.3左右,Be(Ⅱ)-ECAB体系的最大吸收波长为616nm,试剂空白在此波长下吸光度很低,表观摩尔吸光系数为1.11×10~5,比相应的二元络合物灵敏度提高4倍多,亦比采用阳离子表面活性剂作增敏剂时灵敏度高。该体系具有显色速度快,络合物稳定性好,不沾污吸收池和容量瓶,实验操作简便等优点。加入掩蔽剂后,已被用于直接测定矿石中微量铍及铜铍合金试样中含铍量,获得了满意的结果。     

钪-漂蓝6B-羟基(聚氧乙烯)_3磺酸钠三元络合物显色反应的研究

阴离子表面活性剂参与形成的多元络合物显色反应研究,目前研究的尚不多,特别是对金属-三苯甲烷酸性染料配位络阴离子增敏作用一直未见有报导。笔者在资料研究基础上,进一步研究了钪-漂蓝6B-羟基(聚氧乙烯)_3磺酸钠三元络合物显色反应,得到十分有意义的结果。该体系在pH6.5—7.5范围,λ_(max)=660nm,络合物有最大吸收,摩尔吸光系数ε达2.47×10~5;在羟基(聚氧乙烯)_3磺酸钠存在下,钪:漂蓝6B组成比为1:2;0—5μg/25毫     

钪-漂 蓝6B-乳 化 剂 OP 体系的分光光度性质研究

漂蓝6B[Eriochrome Azurol B,简写作 ECAB;Colour Index 43830(1971)]为三苯甲烷类染料,它与许多金属离子生成有色络合物。Vekhande 等曾研究过 Sc-ECAB-CTMAB 显色体系,在 pH6时测钪表观摩尔吸光系数为9.85×10~4。Ca 等报道了在非离子表面活性剂 OS-20、OP-7、OP-10、新坦诺 DS-20等存在下,CAS 与 Al~( 3)、Be~( 2)等多种金属离子的相     

核磁共振法研究三苯甲烷类酸性染料与非离子表面活性剂的相互作用

研究显色螯合剂和表面活性剂之间的相互作用,对于探讨胶束增溶分光光度法的反应机理是很重要的。等曾用核磁共振和分光光度两种方法研究了非离子表面活性剂OS-20与铬天青S(记作CAS)和磺酸铬青的相互作用,并对作用机理提出了他们的看法。本文用NMR研究了非离子表面活性剂TX-100和乳化剂OP与CAS和漂蓝6B(记作ECAB)的相互     

4,5-二溴苯基荧光酮与金属离子的显色反应及混合表面活性剂的作用机理

本文研究了在表面活性剂(Sf)存在下,4,5-二溴苯基荧光酮(简称 diBr-PF)与12个金属离子(Me)的显色反应.结果表明,diBr-PF 是 Me 的一个高灵敏显色剂.用 Hückel 分子轨道法(HMO)计算了 diBr-PF 的(?)电子密度,判断了 diBr-PF 各级 H~+的离解顺序及其和 Me 的配合位置;测定了在不同 Sf 存在下,diBr-PF 的各级酸离解常数(pK_a)及绘制了它的分布曲线;并研究了阳离子型(C-Sf)-非离子型(n-Sf)混合 Sf 对 Me—diBr-PF 显色反应体系的作用机理.     

表面活性剂对共轭聚合物荧光性质及电荷转移的影响

探讨了表面活性剂存在下, 水溶性阴离子共轭聚合物聚[5-甲氧基-2-(3-磺酰化丙氧基)-1,4-苯撑乙烯](简写为MPS-PPV)的微环境变化对荧光性质及电荷转移的影响. 结果表明, 阳离子表面活性剂及非离子表面活性剂使MPS-PPV荧光增强, 阴离子表面活性剂使其荧光先增强后减弱; 在MPS-PPV/表面活性剂体系中加入电子接受体Pd^2＋, 发现非离子表面活性剂体系的荧光猝灭效率提高, 阴离子及阳离子表面活性剂体系荧光猝灭效率下降. 此研究对研制基于阴离子共聚物的新型生物化学传感器具有一定的指导意义.     

表面活性剂存在下，铬菁R与锆(Ⅳ)络合显色反应之研究

锆(Ⅳ)的光度测定已有综述。其中三苯甲烷类试剂应用较广泛,作者等新近提出了PSC法。利用胶束增溶(敏)的方法渐多,其中体系Zr-TAM-Zeph、Zr-CAS-各类表面活性剂、Zr-SAF或m-NPF等2,3,7-三羟基萤光酮衍生物-CTMAB、Zr-Br-BTAE-SLS、Zr-Br-PF-CTMAB-Tween-60等灵敏度高(ε≥10~5)。本文研究了在不同表面活性剂存在下,铬菁R(ECR)与锆(Ⅳ)的络合显色反应。在溴化十六烷基吡啶(CPB)存在下,pH=5时,络合物的最大吸收波长560～590nm(ε_(570)=1.24×10~5),其灵敏度高,适于微量锆的测定。     

非离子表面活性剂的结构对络合物吸收光谱的影响

本文用分光光度和核磁共振两种实验方法研究非离子表面活性剂(记作n-Sf)胶束对漂蓝6B(ECAB)及其金属络合物的增溶增敏作用。n-Sf对金属络合物的增溶增敏作用发生在胶束的极性部分与非极性部分的交界处,故n-Sf分子中的烷基链与聚氧乙烯链是否直接相联,会影响到金属-ECAB络合物的吸收光谱形状、λ_(max)和ε值。n-Sf胶束增溶ECAB,会抑制ECAB的酸式离解。     

漂蓝6B和铬天青B及其在分析化学中的应用

本文总结了漂蓝6B、铬天青B及其在分析化学中的应用。内容包括ECAB的制备、提纯及检验;ECAB的光度性质与酸碱平衡;ECAB的二元显色体系;ECAB的多元显色体系;其它性质应用。     

表面活性剂对共轭聚合物荧光性质及电荷转移的影响

探讨了表面活性剂存在下, 水溶性阴离子共轭聚合物聚[5-甲氧基-2-(3-磺酰化丙氧基)-1,4-苯撑乙烯](简写为MPS-PPV)的微环境变化对荧光性质及电荷转移的影响. 结果表明, 阳离子表面活性剂及非离子表面活性剂使MPS-PPV荧光增强, 阴离子表面活性剂使其荧光先增强后减弱; 在MPS-PPV/表面活性剂体系中加入电子接受体Pd^2＋, 发现非离子表面活性剂体系的荧光猝灭效率提高, 阴离子及阳离子表面活性剂体系荧光猝灭效率下降. 此研究对研制基于阴离子共聚物的新型生物化学传感器具有一定的指导意义.     

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.