铬(Ⅵ)与9-取代-2,3,7-三羟基萤光酮氧化显色反应的研究及其在金属材料分析中的应用

在盐酸与磷酸的混合酸介质中,铬(Ⅵ)与9-取代-2,3,7-三羟基萤光酮(水杨基萤光酮、邻硝基苯基萤光酮以及邻氯苯基萤光酮)反应产生橙黄色氧化产物。其吸收峰位于492-497nm。反应具有很高的选择性,除氧化性物质以外,其他各种金属元素均不干扰铬(Ⅵ)的测定。拟定了用邻硝基苯基萤光酮分光光度法测定各种金属材料中铬的新方法。     

水杨基萤光酮-溴化十六烷基三甲铵高灵敏分光光度法测定微量锰

近年,以非离子表面活性剂增溶,用吡啶偶氮类显色剂在水相测定微量锰的光度法获得了较好的结果。用水杨基萤光酮-表面活性剂体系光度法测定微量锰的研究尚未见报导。本文探讨了用水杨基萤光酮-溴化十六烷基三甲铵体系光度法测定锰的最佳条件。试验表明,在pH8.6～9.8范围内,锰与水杨基萤光酮和溴化十六烷基三甲铵生成可溶于水的蓝紫色络合物,最大吸收波长为562nm,摩尔吸光系数高达1.31×10~5,是目前水相介质中光度法测定锰灵敏度最高的体系。     

2,4-二氯苯基萤光酮-溴化十六烷基三甲基铵分光光度测定钽

2,3,7-三羟基-9取代基萤光酮是胶束增敏分光光度法中一类高灵敏的显色剂,已有用水杨基萤光酮,二溴苯基萤光酮测定钽的报导,但直接测定均只是铌钽合量。我们用自行合成的九种不同9取代三羟基萤光酮,对铌和钽的测定性能作了系统的比较,从中筛选出灵敏度高、选择性好的2,4-二氯萤光酮,推荐作为测钽的优良试剂。因在2～3.6N高酸度下     

水杨基萤光酮析相光度法测定微量铝

1引言萤光酮试剂是一类重要的有机显色剂，在分析化学中有着广泛应用，但未见水杨基萤光酮（SAF）析相光度法测定铝的报道。本文研究了铝一水杨基萤光酮（SAF）TritonX－100析相光度体系，建立了测定微量铝的方法。应用于茶叶中微量铝的测定，结果满意。2实验部分2．1主要试剂和仪器铝标准液：1g／L贮备液及2．0mg／L工作液，水杨基萤光酮溶液：O．05％乙酮溶液六次甲基四肢一盐酸缓冲液；pHS：0；Trit。fiX－100溶液：20％水溶液。721型分光光度计；pHS－2型酸度计；501型超级恒温器。2．2试验方法取2Pg铝于50mL桥相管中，加5％抗…     

间硝基苯基萤光酮-溴化十六烷基三甲铵分光光度法测定微量钼

目前,在测定钼的分光光度法中,灵敏度、选择性及不用萃取等各种性能均优的首推水杨基萤光酮溴化十六烷基三甲铵胶束增敏分光光度法。该法的表观摩尔吸光系数ε达1.4×10~5。但该法在消除钛、钨的干扰方面还无有效办法。所以,若试样中含钛、钨,则使用该法测钼仍有一定困难。在钢铁合金、矿物岩石中,钼、钨、钛共存的情况极其普遍,尤其是钼、钨,它们的性质相似,在自然界常作为伴生元素存在。这样,寻找既能消除钨的干扰、灵敏度又高的测定钼的方法就显得十分必要。本文所研究的用间硝基苯基萤光酮胶束增敏测定钼的反应在灵敏度上与水杨基萤光酮方法差不多(用751G型分光光度计测出     

阳离子表面活性剂存在下锗与2,3,7-三羟基-9-取代萤光酮显色反应的研究

本文研究了八种2,3,7-三羟基-9-取代荧光酮在阳离子表面活性剂存在下与锗的胶束增敏显色反应.发现水杨基萤光酮及邻硝基苯基萤光酮在强酸性介质中可以和溴化十六烷基三甲基铵形成高灵敏的胶束三元配合物.较详细地研究了用邻硝基苯基萤光酮与溴化十六烷基三甲基铵分光光度法测定微量锗的实验条件.并探讨了有关配合物的组成以及胶束增敏反应的机理.此法可不经分离,直接快速测定铅锌矿中的微量锗,结果比较满意.     

水杨基萤光酮-N-氯化十六烷基吡啶双波长光度法测定钢铁中微量铬

近年来,利用阳离子表面活性剂增敏光度法测定Cr(Ⅵ),见报道的有。其中用高灵敏显色剂萤光酮衍生物的则有,Cr(Ⅵ)-邻羟基氢醌酞-CTMAB(ε=1.64×10~5),Cr(Ⅵ)-二溴苯基萤光酮-CPB(ε_(580)=1.44×10~5)和Cr(Ⅵ)-水杨基萤光酮-CTMAB(ε_(585)=1.2×10~5),前者选择性不理想。本文提出用水杨基萤光酮-CPC双波长光度法测定Cr(Ⅵ),ε_(580)=2.6×10~5,为目前水相光度测定Cr(Ⅵ)的最高值,用于钢铁中微量铬的测定,结果满意。     

水杨基萤光酮-溴化十六烷基三甲基铵分光光度法测定金属材料中的微量锡

在阳离子表面活性剂存在下,利用邻苯二酚紫,苯基萤光酮,茜素紫等试剂测定锡的方法具有较高的灵敏度。例如,苯基萤光酮-溴化十六烷基三甲基铵法的摩尔吸光系数可达到1.34×10~5。本文研究用水杨基萤光酮(SAF)-溴化十六烷基三甲基铵(CTMAB)分光光度法测定微量锡。本法在灵敏度和选择性方面比上述各法均有较大的提高。方法的表观摩尔吸光系数。ε=1.79×10~5(在751型分光光度计上测得)。由于显色反应的酸度较高,因此,除钛、钼、钨、锑     

非离子表面活性剂——水杨基萤光酮分光光度法测定微量钛

近年来,表面活性剂的应用使得微量钛的光度法测定得到了较大的进展。据文献报道,在多数方法中,均采用阳离子表面活性剂。不久前,王淑仁等曾经用非离子表面活性剂(OP-10)-苯基萤光酮分光光变法测定钛。方法灵敏度较使用阳离子表面活性剂要高。鉴于水杨基萤光酮比苯基萤光酮具有更好的分沂     

二溴苯基萤光酮──TritonX－100高灵敏分光光度法测定水中微量锰

二溴苯基萤光酮──ＴｒｉｔｏｎＸ－１００高灵敏分光光度法测定水中微量锰胡家元，何小蓓，杨素清（四川大学化学系，成都，６１００６４）关键词分光光度法，二溴苯基萤光酮，锰取代苯基萤光酮是一类应用十分广泛的高灵敏显色剂，近年已被用于许多金属离子的光度分析￣...     

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.