钒(Ⅴ)-硫胺素荧光反应的研究及应用

本文首次提出了以硫胺素为荧光剂测定微量钒的新方法。该法基于 V(V)-硫胺素反应生成荧光物质,其λ_(ex)=400nm,λ_(em)=464nm,当钒的浓度在2.5×10~(-7)～1.75×10~(-5)mol/L 范围内与荧光强度呈良好的线性关系,用本法测定了粮食样品中的微量钒,获得了满意结果。     

新显色剂偶氮8-羟基喹啉苯基荧光酮的研究与应用——Ⅱ.分光光度法测定镓

2,6,7-三羟基-9-[4-(8-羟基-5-喹啉偶氮基)苯基]荧光酮是一种新的显色剂。该试剂在微碱性溶液中为橙黄色,有CTMAB和F~-存在下与镓形成四元紫红色络合物。络合物λ_(max)=568nm,表观摩尔吸光系数ε′_(568)=2.23×10~5L·mol~(-1)·cm~(-1),用双波长倍增法测得ε′_(568-496)=3.21×10~5L·mol~(-1)·cm~(-1),比单波长法灵敏度提高约44％。用拟定的方法,进行地质样品中痕量镓的测定,得到令人满意的结果。     

对三氟甲基偶氮氯膦的合成及其稀土络合物分光光度法的研究——铝合金中稀土总量的测定

合成了新的稀土显色剂对三氟甲基偶氮氯膦。研究了用此显色刑测定铝合金中稀土总量的分光光度法。在酸性介质中与稀土元素成正序反应。轻稀土λ_(max)=668nm,ε=0.96～1.02×10~5·L·mol~(-1)·cm~(-1);重稀土λ_(max)=659nm,ε=1.03～1.29×10~5L·mol~(-1)·cm~(-1)。     

水杨醛异烟酰腙与镓荧光反应的研究

本文研究了荧光新试剂水杨醛异烟酰腙与镓的荧光反应,用紫外光谱法测定了试剂离解常数。在此荧光体系中,荧光配合物λ_(ex)=395nm、λ_(em)=480nm。在pH3.8、60％(V/V)乙醇介质中,测定的线性范围为0～1.0 μg/10mL,方法灵敏度为4×10~(-4)ppm。用荧光法测定了配合物的组成比及表观稳定常数。建立了镓的新荧光光度法,将其用于地质样品分析,精密度和准确度良好。     

溴金酸-罗丹明B和氯金酸-罗丹明6G超高灵敏显色反应的研究——离心光度法测定金

本文研究了一个超高灵敏的测定金的方法,离心光度法。在Au-Br-RB体系中络合物λ_(max)=559nm,表观摩尔吸光系数ε_(559)=3.39×10~(11)L·mol~(-1)·cm~(-1),Au(Ⅲ)浓度(0.20×10~(-5)～2.5×10~(-5)μg/10 ml呈线性关系;Au-Cl-R6G体系络合物λ_(max)=531 nm,表观摩尔吸光系数ε_(531)=2.52×10~8L·mol~(-1)·cm~(-1),Au(Ⅲ)浓度(0.20×10~(-2)～2.4×10μg/10ml。呈线性(Ⅲ)关系。本法已用于某些低品位矿样中金的分析,分析结果与标准值相吻合。探讨了超高灵敏的显色反应机理。     

meso-四-(4-甲氧苯基)卟啉-镉(Ⅱ.)-[(OP-Tween-80)或(Tween-80)]显色体系及其双波长和导数光谱行为研究

本文研究了meso-四-(4-甲氧苯基)卟啉与Cd(Ⅱ)在表面活性剂〔(OP+Tween-80)或(Tween-80)〕存在下的显色反应,并对它们的双波长及导数光谱行为进行了探讨。结果表明,在碱性介质中该试剂与Cd(Ⅱ)均形成1:1配合物,λmax为438.5nm,ε＇_(438 .5)(OP+Tween-80)=4.85×10~5,ε＇ _(438.5)(Tween-80)=4.05×10~5,ε_(438.5/422)~双波长(OP+Tween-80)=8.75×10~5,ε_(438.5)~四阶导数(Tween-80)=8.57×10~6。混合增溶体系灵敏度高,选择性好,而Tween-80体系简单。两者的合成样品测定回收率在94.50～109.00％之间。     

二溴羧基苯基重氮氨基偶氮苯的合成及其与镉显色反应的研究

本文首次合成了二溴邻羧基苯基重氮氨基偶氮苯(DB-o-CDAA)和二溴对羧基苯基重氮氨基偶氮苯(DB-p-CDAA)。在pH10.2的硼砂-氢氧化钠缓冲介质中,以TritonX-100为增溶增敏剂,两种试剂均可与Cd(Ⅰ)生成稳定的橙红色络合物。其DB-o-CDAA-Cd,λ_(max)=520nm,ε_(520)=2.21×10~5L·mol~(-1)·cm~(-1);DB-p-CDAA-Cd,λ_(max)=508nm,ε_(508)=1.12×10~5L·mol~(-1)·cm~(-1)。镉量在0～10μg/25ml范围内遵守比耳定律。用这两种试剂测定了环标水样及工业废水中的痕量镉,结果满意。     

双硫腙萃取双波长系数倍率法测定铂和钯的研究及应用

在1mol/L盐酸溶液中,当氯化亚锡存在时,用双硫腙溶液同时萃取铂和钯,双波长系数倍率法测定。测定铂时,λ_1为600nm、λ_2为710nm,K=7,测定钯时,λ_1为720nm。λ_2为638nm,K=3.5。铂和钯均在0～1.0μg/ml浓度范围内符合比尔定律,表观摩尔吸光系数分别为2.01×10~5L·mol~(-1)·cm~(-1)和1.10×10~5L·mol~(-1)·cm~(-1)。本文还探讨了氯化亚锡在萃取反应中的作用机理。方法简便、选择性好,用于地质样品中痕量铂和钯的测定,可获得满意的结果。     

5—Br—PADAP双波长系数补偿吸光光度法测定钯铑

本文研究了5-Br-PADAP与Pd、Ru的显色反应,加入OP增溶,CTMAB作稳定剂,在pH3.1～4.5形成1:1的橙色络合物,ε_(pd)=4.3×10~5,ε_(pd)=1.3×10~5,表观稳定常数k′_(pd)=6.0×10~7,k′_(Rd)=1.52×10~5。Pd在0～1.01μg/25ml及Ru在0～2.2μg/25ml范围内符合比耳定律,最大吸收波长λ_(pd)=488nm,λ_(Rd)=484nm。本文采用系数补偿法捉高了双波长光度法的灵敏度,于Pd、Ru混合液中同时测定Pd、Ru,回收率分别为97.07％和100.9％。结果令人满意。     

5-(4-硝基苯偶氮)-8-(4-甲苯磺酰氨基)-喹啉的合成及在钴的测定中的应用研究

首次合成了5-(4-硝基苯偶氮)-8-(4-甲苯磺酰氨基)-喹啉,测量了其酸离解常数。在非离子型表面活性剂存在下,试剂与钴(Ⅱ)在pH9.0～11.2范围内形成配合物,ε_(645)=1.01×10~5L·mol~(-1)cm~(-1),在H_2o_2作用下,于λ_((?)m)/λ_((?)x)=420nm/345nm产生强荧光,建立了一个操作简便快速、灵敏度高、选择性好的荧光分析新方法,线性范围2～32ppb,检测极限0.1ngCo(Ⅱ)/ml,用以测量了维生素B_(12)及生物样品中的痕量钴(Ⅱ)。探讨了H_2O_2对荧光增敏的机理。     

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.