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.     

钛(Ⅳ)-氯磺酚S-N-苯甲酰苯基羟肟酸三元配合物及其分析应用

本文研究了钛(Ⅳ)一氯—磺酚S—N—苯甲酰苯基羟肟酸三元混配配合物的形成条件,提出了一个快速简便的分光光度法,用于测定硅酸盐矿物中的微量钛。Ti(Ⅳ)量在0—20μg/25ml符合比尔定律,λ=660nm,ε=1.98×10~4L.mol.cm~(-1)。     

丁基罗丹明B-硫氰酸盐-吐温-20体系高灵敏分光光度法测定微量硒的研究

本文叙述了在吐温-20存在下用硫氰酸盐和丁基罗丹明B形成缔合型三元配合物测定微量硒(Ⅳ)。配合物的最大吸收波长为600nm,硒含量在0—5μg/25ml服从朗伯比尔定律,其ε_(600)=6.4×10~5,重现性好,选择性高,是目前测定微量硒的一种高灵敏度的新的分光光度法,已用于水样中微量硒的测定。     

二溴硝基偶氮氯膦与铝显色反应的研究及应用

研究了在pH4.8乙酸盐介质中,Al(Ⅲ)与DBNCPA的显色反应.该配合物的最大吸收波长位于620nm,摩尔吸光系数∈_(620)为3.6×10~4,AI(Ⅲ)含量在0～14μg/25ml范围内符合比耳定律.方法具有较好的选择性,用于人发、食物中微量铝的测定,结果满意.     

新试剂7-(苯并噻唑-2-偶氮)-8-羟基喹啉-5-磺酸的合成及与钴显色反应的研究

报道了新试剂7-(苯并噻唑-2-偶氮)-8-羟基喹啉-5-磺酸(BTHQSA)的合成方法,研究了该试剂与钴显色反应情况.结果表明,在pH3.94乙酸-乙酸钠、乳化剂OP存在下,Co-BTHQSA-OP配合物最大吸收波长为582nm,表观摩尔吸光系数ε_(582)=-5.7×10~4,钴的含量在0～12μg/25ml内,服从比耳定律.     

DMTADAT光度法钴、钯同时测定的研究

本文提出,在高氯酸介质中,以5-(4,5-二甲基噻唑偶氮)-2.4-二氨基-甲苯(简称DMTADAT)作为显色剂进行钴,钯同时测定的新方法。在实验条件下,钴、钯与试剂形成配合物的摩尔吸光系数为ε_(CoL2)~(605)=9.3×10~4,ε_(PdL)~(610)=5.4×10~4。钴在0～10μg/25ml,钯在0～35μg/25ml浓度范围内服从比尔定律。所拟方法已成功地应用于矿样中钴、钯的同时测定。     

钴钯同时测定的新方法

用2-吡啶偶氮类衍生物分光光度法测定微量钴,虽然灵敏度高,但钯的干扰较严重,至今尚未见简单的消除方法。本文采用5-[(5-氯2-吡啶)偶氮]-2,4-氨基甲苯(简称5-Cl-PADAT)作显色剂,提出利用差减法消除测定钴时钯的干扰,以及钴、钯同时测定的新方法。在实验条件下,钴和钯与试剂分别形成1:2和1:1的紫红色配合物。配合物的最大吸收波长在570nm处,摩尔吸光系数ε_(Co)=1.20×10~5,ε_(Pd)=6.90×10~4。钴浓度在0～10μg/25mL,钯浓度在0～25μg/25mL时符合Beer定律。该法灵敏度高,选择性好,手续简单,快速,用于钯精矿,钢样及分子筛中微量钴和钯的同时测定,获得了良好的结果。     

酸性介质中PAR与Fe（Ⅱ）显色反应的研究及其应用

4-(2-吡啶偶氮)间苯二酚(PAR)是常用的配位滴定指示剂和光度分析显色剂,能用于多种金属离子的光度测定.用PAR光度法测定Fe(Ⅱ),因PAR及其PAR与Fe(Ⅱ)的配合物在酸性介质中难溶于水,因而一般在选择性不够高的碱性介质中进行测定.迄今为止,PAR与Fe(Ⅱ)在酸性介质中的显色反应研究还未见报道,本法采用加入表面活性剂OP增溶,研究在酸性介质中PAR与Fe(Ⅱ)的显色反应.结果表明,在pH2.0～6.0的范围内,Fe(Ⅱ)与PAR形成稳定的1:2配合物,最大吸收波长为491nm和710nm,表观摩尔吸光系数ε_(710)为1.4×10~4L·mol~(-1)·cm~(-1),以710nm为测定波长,铁含量在0～45μg/25ml范围内服从比耳定律.方法选择性较高,用于测定茶叶和食品中微量铁,结果满意.     

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。     

4-(6-溴-2-苯并噻唑偶氮)邻苯二酚-钛(Ⅳ)-丙酮体系显色反应的研究

新有机试剂4-(6-溴-2-苯并噻唑偶氮)邻苯二酚(6-Br-BTAPC)与钛(Ⅳ)在 pH3.4的40%丙酮水溶液中发生高灵敏显色反应。形成的带负电荷的配合物的组成比为2:1表观稳定常数为3.7×10~9(25℃,μ0.1),λ_(max)为570nm,对比度(Δλ)为130nm,ε_(570)高达9.21×10~4L·mol~(-1)·cm~(-1)。建议了配合物的结构。在0～13μgTi(Ⅳ)/25ml 范围内遵从比耳定律。该法用于工业水和废水中痕量钛的分光光度测定,取得了满意的结果。     

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.