新显色剂二溴羧基偶氮胂光度法测定锆的研究

介绍了用二溴羧基偶氮胂测定微量锆的方法.在 1.56mol·L~(-1)HCl介质中,试剂与锆形成1:3的蓝色配合物.在640nm波长处,摩尔吸光系数为2.8×10~4,锆量在0～18μg/25ml范围内符合比耳定律,多数离子和三倍量的铪不影响测定.所拟方法简便快速,选择性强,应用于铜合金中锆的直接测定,取得了令人满意的结果.     

新显色剂对碘偶氮氯膦-Zr(Ⅳ)反应的吸光光度法研究

报道了新显色剂对碘偶氮氯膦与锆的最佳显色条件.在盐酸一硫酸介质中,锆与显色试剂形成1:1的蓝色配合物.其最大吸收峰位于690nm处,摩尔吸光系数ε为6.88×10~4,锆量在0～10μg/25ml范围内符合比耳定律.方法已用于不含稀土的铝合金样品中微量锆的测定,结果满意.     

3,5-diBr-PADAP作锆(Ⅳ)显色剂的分光光度法研究与应用

本文研究了在非离子表面活性剂存在下,用3,5-diBr-PADAP作锆显色剂的胶束增溶分光光度法。在pH1.0～2.0的HCl介质中,配合物吸光度最大且稳定,最大吸收值在610nm处。Zr(Ⅳ)与试剂形成1:2的配合物,摩尔吸光系数为1.10×10~5L·mol~(-1)·cm~(-1),zr(Ⅳ)量在0～30μg/25mL范围内遵守比尔定律。采用钽试剂一苯苹取分离法,适合于钽铌矿中微量锆的测定。     

锆—马尿酸偶氮氯膦—CPB—乙醇显色体系的研究

马尿酸偶氮氯膦是一种灵敏稀土显色剂,为扩大其分析应用范围,我们研究了它与锆的显色反应。在阳离子表面活性剂CPB与适量乙醇存在下,锆与该试剂显色反应的灵敏度较其二元配合物可提高4倍,并能允许较大量Cu~(2+)、Mg~(2+)、Co~(2+)、Ni~(2+)和Mn~(2+)等离子共存,可用于铜合金中微量钴的直接测定。与氨基G酸偶氮氯膦测定微量锆的方法相比,实验条件与选择性     

锆钼杂多酸-耐尔蓝离子缔合显色反应的研究

在聚乙烯醇(PVA)存在下,耐尔蓝(NB)与锆钼杂多酸(ZrMo)形成离子缔合物,其λ_(max)位于615nm,表观摩尔吸光系数e值为3.71×10~5L·mol~(-1)·cm~(-1),线性范围0～5μgzr/25ml。络合物至少稳定24h。考察了30多种共存离子的影响,允许25倍量铪存在。测定锆的适宜条件为[HClO_4]=0.9mol/L,[MoO_4~(2-)]=7.5×10~(-5)mol/L,[NB]=5.5×10~(-5)mol/L,PVA 0.08％。方法已用于岩矿中锆的测定,结果满意。用摩尔比法和平衡移动法测定缔合物的摩尔比为ZrMo:NB=1:4。探讨了反应机理。     

单试剂双波长光度法同时测定铝合金中钛与铁

研究了磺基水杨酸(SSA)与钛、铁同时显色反应及测定的适宜条件。试验结果表明,在pH2～3的邻苯二甲酸氢钾-盐酸缓冲液中,SSA与钛、铁可形成稳定有色配合物,以500nm为SSA—Fe配合物的测定波长,采用365/560nm为SSA—Ti配合物测定波长对,钛量在0～22μg/25ml,铁量10～200μg/25ml符合比耳定律,配合物的表观摩尔吸光系数ε_(Ti)为2.0×10~4,ε_(Fe)为3.0×10~3,方法简便、快速、结果良好。     

新试剂DBN-偶氮胂与钍显色反应的研究及应用

对分光光度测定钍的显色剂,Savvin和Florence作过评述,认为偶氮胂Ⅲ是测定钍的良好试剂。在4-9N HCl介质中,钍与偶氮胂Ⅲ形成绿色配合物,摩尔吸光系数为1.3×10~5,但铀、稀土和钛严重干扰测定。继偶氮胂Ⅲ之后,有对乙酰基偶氮胂、间磺基偶氮氯膦、偶氮硝膦-mN、三溴偶氮胂、对溴偶氮氯膦等。用这些试剂光度法测定钍、铀、锆、钛的允许量有不同程度的提高,但稀土的干扰仍较严重。本文提出我们     

对乙酰基偶氮胂双波长吸光度差法测定钙

研究了对乙酰基偶氮胂与钙的显色反应.结果表明,在pH10.7的氢氧化钠介质中形成1:2稳定的蓝色格合物;以520nm为参比波长,630nm为测定波长,用双波长吸光度差法测得ε_(520～630)=2.l×10~4.钙量在0～30μg/25ml范围内符合比耳定律.本法用于高纯铁粉、钛酸钙、锆酸钙烧结物及水样中钙量的测定,结果令人满意.     

硝基磺酚K胶束增敏分光光度法测定微量锆的研究

本文研究了表面活性剂胶束对硝基磺酚K与锆的显色反应的增敏作用以及对反应选择性的影响。在阳离子表面活性剂存在下,配合物中锆与硝基磺酚K的组成比为1:3,配合物的最大吸收峰红移至668nm,摩尔吸光系数增大到1.10×10~5L.mol~(-1).cm~(-1)。反应选择性得到很大的提高。拟定了一个灵敏度较高、选择性较好的分光光度测定锆的新方法。用于岩矿分析时,得到良好的效果。     

二甲酚橙-锆(Ⅳ)配合物光度法测定蛋白质

在酸性溶液中,蛋白质与二甲酚橙-锆(Ⅳ)配合物能够相互作用形成超分子复合物,其最大吸收波长较二甲酚橙-锆(Ⅳ)配合物红移了50 nm。在实验选定最佳条件下,600 nm波长处的吸光度与牛血清白蛋白(BSA)、人血清白蛋白(HAS)均在0.2~16μg/mL范围内呈线性关系,相对标准偏差为0.83%(n=7),检出限为0.1 mg/L。该法灵敏度高,选择性好,用于人血清总蛋白含量的测定,结果满意。     

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.