氟离子配位在氧化法制备高铁(Ⅵ)酸盐中的作用

氟离子配位在氧化法制备高铁(Ⅵ)酸盐中的作用;高铁(Ⅵ)酸盐;六氟合铁(Ⅲ)酸钾;次氯酸钠;稳定性     

光度法测定磷铜中间合金中磷的氧化条件讨论

吸光光度法测定磷 ,无论是磷钼黄法还是磷钼蓝法 ,或是磷钒钼三元络合物法 ,都要求磷以正磷酸分子参加化学反应 ,所以把磷的各种低价化合物氧化为五价的正磷酸是光度法测定磷的首要条件。如不少分析方法中测定铜合金中磷也采取了用各种氧化剂氧化磷呈正磷酸尔后测定。测定磷铜中间合金中磷 ,文献 [1～ 3]均采用磷钒钼三元络合物方法 ,该法简单、快速、准确、重复性好 ,倍受分析工作者欢迎。分析方法采用混合酸(ＨＮＯ3∶ＨＣｌ∶Ｈ2 Ｏ =32 0∶12 0∶5 6 0 )溶样 ,滴加Ｈ2 Ｏ2 氧化磷 ,加ＨＣｌＯ4 冒烟使磷进一步完全氧化为正磷酸 ,再进行…     

电位滴定法测定混合稀土中的铈含量

容量法测定混合稀土中铈的含量,通常系采用硫酸亚铁铵法,应用此法,测定条件不易控制,重现性差。本文提出用电位滴定法测定。测定原理为:在pH值为4—5的溶液中,铈(Ⅳ)与钼磷酸能形成稳定的三元杂多酸阴离子[CeL_2]~(10-)(L=PMo_(11)O_(39)~(7-)),导致铈(Ⅳ)氧化还原电位锐降(E_[CeL2]~0~(10-)/[CeL2]~(11-)=0.72伏),因此不必按照硫酸亚铁铵法那样需用Ag~+离子为催化剂即可容易地将铈(Ⅲ)定量地氧化成高价态。但所形     

快速测定水质的化学需氧量

化学需氧量ＣＯＤ(ＣｈｅｍｉｃａｌＯｘｙｇｅｎＤｅｍａｎｄ)是作为衡量水体受污染程度的一个重要综合指标。国标法中采用重铬酸钾作为强氧化剂 ,通过它氧化还原物质所消耗的量来计算氧的量[1] 。许多试验已证明重铬酸钾在酸性介质中 ,能使水体中还原物质的氧化率达 90 %～ 10 0 % [2 ] 。但是应用经典回流滴定法 ,测定范围在ＣＯＤ值 30～ 70 0ｍｇ·Ｌ-1,而日常检测的水源水ＣＯＤ值常在 10ｍｇ·Ｌ-1以下。为减少误差、提高效率 ,本文采用恒温箱加热、重铬酸钾吸光光度法来快速测定ＣＯＤ值。此方法与回流法比较 ,除了快速、简便、还能…     

流动注射化学发光植物组织传感器测定草酸盐

草酸是尿道结石主要成因之一 .统计结果表明 ,90 %以上结石均含草酸钙 .回肠病、口角性肠胃炎及脂肪吸收不良均可引起尿液中草酸的增加 .草酸盐的测定在临床上具有重要意义 .微量草酸测定的传统方法是变色酸比色法或偶氮化合物比色法[1 ] .测定草酸盐的方法还有原子吸收光谱法[2 ] 、高效液相色谱法[3] 、离子色谱法[4] 、光度法[5] 和草酸氧化酶法[6] 等 .这些方法或操作复杂、耗时 ,或灵敏度低 ,使其应用受到限制 .本文提出一种测定草酸盐的新方法 ,其原理为草酸 +Ｏ2草酸氧化酶 ＣＯ2 +Ｈ2 Ｏ2 ,Ｌｕｍｉｎｏｌ+Ｈ2 Ｏ2 ｈｖ　　将含有草…     

十二烷基苯磺酸钠氧化降解的研究

随着工农业的发展,表面活性剂已广泛应用于各个领域,表面活性剂废水的大量排放成为水体CODCr的重要来源.目前对此类废水的降解研究主要集中于生物法和光催化法[1].高铁酸盐具有强氧化性,在水处理方面可用于杀灭藻类和细菌[2],氧化降解水中的污染物[3,4]等,本研究以十二烷基苯磺酸钠(SDBS)水溶液作为表面活性剂模拟废水,研究高铁酸盐(FeO42-)对其处理效果和降解机理.实验结果表明,新型水处理剂高铁酸盐可以有效降解SDRS.     

溶液中Fe(Ⅵ)向Fe(Ⅳ)转化反应的分光光度法跟踪

Fe(Ⅵ)化合物因其强氧化性所展现的光明应用前景,正成为研究热点[1].相比之下,对Fe(Ⅳ)化合物人们却知之不多.据文献[2]报道,Fe(Ⅵ)化合物在高碱度溶液中呈绿色,且能稳定存在.通常被称作高铁酸盐的FeⅥ)化合物在碱性溶液中以FeO42-形式存在而呈紫色,高浓度时不稳定,在酸、碱介质中均会分解放出氧气并生成Fe3+或Fe(OH)3.本文采用分光光度法跟踪监测碱性溶液中Fe(Ⅵ)化合物的分解过程,发现除生成Fe(OH)3外,还有Fe(Ⅳ)化合物的绿色溶液生成.在此基础上,对完成这一转化的条件进行了研究,取得了有益的结果,从而深化了对Fe(Ⅵ)和Fe(Ⅳ)化合物重要性质的认识.     

硫代硫酸钠置换滴定法测定高铁酸盐的纯度

正高铁酸盐是高铁酸根离子(FeO_4~(2-))与金属阳离子结合形成的盐类,常见的高铁酸盐有Na_2FeO_4、K_2FeO_4、CaFeO_4、BaFeO_4、ZnFeO_4等。高铁酸盐作为一种新型绿色多功能材料,在环境工程、有机合成、化学电源等领域都具有广阔的应用前景[1-3]。高铁酸盐作为水处理剂应用于环境工程,不仅氧化水体中难降解的有机污染物,灭活有害细菌和藻类等微生物,而且其产物Fe~(3+)可形成絮凝剂进一步吸附去除污染物[4-8]。高铁酸盐作为绿色氧化     

β-环糊精衍生物的金属配合物模拟酶催化测定葡萄糖含量

葡萄糖含量常用生物酶法[1 ] 间接测定 ,但酶试剂较贵 ,且多数对酸、碱、热不稳定 ,反应条件苛刻、易失去活性。模拟生物酶测定一直是分析化学领域研究的热点之一[2 ] 。 (本文利用双 [6-氧- (丁烯二酸 - 1 ,4-单酯 - 4) ]β -ＣＤ·Ｆｅ3+·Ｈ2 Ｏ2同时模拟葡萄糖氧化酶 (ＧＯＤ)和过氧化物酶(ＰＯＤ) ,Ｈ2 Ｏ2 与邻甲苯胺生成的氧化型产物在波长 365ｎｍ处有较强的吸收[3] ,通过测定 365ｎｍ处吸光度的变化对葡萄糖进行定量分析。该模拟酶具有制备简便、费用低廉、寿命长、不易失活等优点。该法检测下限可达 1 5ｍｇ·Ｌ- 1 。模拟酶制备…     

亚铬酸盐滴定法测定高铁酸钾

以亚铬酸盐氧化还原反应为基础建立了K2FeO4的滴定分析方法.对滴定分析条件进行了进一步的研究,结果表明,用氢氧根离子浓度为 16～17 mol/L的亚铬酸盐溶液测定高铁时,所取高铁样品的质量影响所测的高铁含量.     

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.     

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.     

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.     

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.