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)。     

用新紫外光度法测定水中亚硝酸盐氮的研究

碱性品红与亚硝酸根在硫酸介质中反应 ,反应产物在近紫外区有一吸收峰 ,其λmax在 2 6 5nm .其NO-2 -N含量在 0～ 0 .6mg/L范围内符合比尔定律 ,ε=1.2 0 5× 10 4L·mol- 1·cm- 1,据此建立了一个简单、快速、选择性好的测定亚硝酸盐氮的新方法 .用于地表水、地下水的测定 ,结果与盐酸萘乙二胺比色法一致 .     

显色剂交换萃取吸光光度法测定微量铜

用三氯甲烷萃取Cu-DDTC络合物,然后在pH=9.2三羟甲基氨基甲烷(Tris)缓冲液中用5-Br-PADAP交换络合物中DDTC,形成了Cu-PADAP络合物。该络合物最大吸收波长λ_(max)=520nm,表观摩尔吸光系数ε_(520)=1.22×10~5,铜量在0.2～10.0μg/12ml范围内服从比耳定律。本法应用于食品、生物材料中微量铜测定,得到较为满意的结果。     

紫外光谱区分光光度法测定微量铁

铁与磺基水杨酸在pH5.6～6.0范围内形成的1:2络合物,在紫外光谱区波长约248nm处有一尖形吸收峰,灵敏度很高,摩尔吸光系数ε=2.82×10~4L·mol~(-1)·cm~(-1),比可见光区ε=4.25×10~3L·mol~(-1)·cm~(-1)提高了5倍,利用导数法可以提高到ε=1.20×10~5L·mol~(-1)·cm~(-1),是可见光区的24倍。     

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。     

钍(Ⅳ)与偶氮溴膦-mB和溴化十四烷基吡啶在乙醇-水溶液中的显色反应及其分析应用

在pH1～2的酸性介质中,钍(Ⅳ)与偶氮溴膦-mB(BPAmB)形成最大吸收波长(λ_(max)位于686nm的蓝色络合物,摩尔吸光系数(ε)为8.27×10~4L·mol~(-1)·cm~(-1).在有少量乙醇存在的0.5～1.0 mol/L盐酸溶液中,钍(Ⅳ)能与BPAmB和溴化十四烷基吡啶形成更灵敏的三元络合物,最大吸收位于695nm,具有更大的对比度(△λ=135nm)和更高的灵敏度.ε值达1.41×10~5L·mol~(-1)·cm~(-1),是目前光度法测定钍(Ⅳ)灵敏度最高的显色反应之一,Th(Ⅳ)的浓度在0～800μg/L范围内遵守比尔定律.方法具有良好的选择性,此法用于岩矿中微量钍的测定,结果满意.     

三辛基氧膦萃取光度法连续测定矿石中微量铀和钍

同一份称样中微量铀和钍采用三辛基氧膦(TOPO)萃取光度法连续测定,一般文献中所列步骤均较烦琐。本文采用TOPO一次萃取,有机相用0.1mol/L H_2SO_4反萃取钍,经洗涤后直接用5-Br-PADAP-F-光度法测定铀;反萃取液则在0.5mol/L HCl介质中,采用偶氮氯膦mV(CPA-mN)-溴化十六烷基三甲铵(CTMAB)-二苯胍(DPG)多元络合物法测定钍。钍络合物的λ_(max)=670nm,ε_(670)=1.6×10~5,钍量在0—12.5μg/25mL范围内符合比尔定律,组成比Th(Ⅳ):CPA-mN=1:5;铀络合物的λ_(max)=575nm,ε_(575)~5=7.8×10~4,铀量在0—17     

5-苯基偶氮-8-(4-羧基苯偶氮氨基)喹啉与铜(Ⅱ)显色反应研究

合成了5-苯基偶氮-8-(4-羧基苯偶氮氨基)喹啉(PACPAQ)。在pH8.2的硼砂缓冲介质中,在CTMAB存在下,铜(Ⅱ)与PACPAQ形成1:4紫红色络合物,λ_(max)为540nm,ε=6.9×10~4·L·mol~(-1)·cm~(-1),铜量在0～10μg/25ml范围内符合比尔定律.用于粗铅和水中铜的测定,结果满意。     

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。     

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。     

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.