二阶导数光谱-峰面积积分法同时测定痕量锗和钼

在苯基荧光酮 氯代十六烷基吡啶(CPC)胶束体系中,引入二阶导数光谱 峰面积积分技术,建立了同时测定微量锗和钼的新方法。该方法可有效消除共存离子的干扰,提高了准确度和灵敏度。实验表明:锗质量浓度在0～15μg/mL、钼质量浓度在0～8μg/mL均呈线性关系。摩尔吸光系数锗ε509为1.4×105L·mol-1·cm-1;钼ε540为5.9×104L·mol-1·cm-1。方法检出限锗为3.3μg/L;钼为6.9μg/L。可用于中药材中锗和钼的同时测定。     

DBC-偶氮氯膦固相光度法测定稀土元素铈,铕,钇

在2 mol/L HCl介质中,Ce(Ⅲ),Eu(Ⅲ),Y(Ⅲ)与DBC-偶氮氯膦形成的络合物吸附到201×7型强碱性苯乙烯阴离子树脂上。最大吸收波长Ce(Ⅲ)络合物为648 nm,Eu(Ⅲ)络合物为650 nm,Y(Ⅲ)络合物为650 nm。Ce(Ⅲ)络合物表观摩尔吸光系数为6ε48 nm=9.6×104L.mol-1.cm-1,Eu(Ⅲ)络合物表观摩尔吸光系数为6ε50 nm=1.51×105L.mol-1.cm-1,Y(Ⅲ)络合物表观摩尔吸光系数为6ε50 nm=5.6×104L.mol-1.cm-1。固相光度法测定Ce(Ⅲ),Eu(Ⅲ),Y(Ⅲ)质量浓度在0~0.48μg/mL范围内与吸光度值呈良好线性关系。该法可用于分子筛中Ce的测定。     

磷钼蓝体系薄层树脂相吸光光度法测定痕量钼的研究

提出了在酸性条件下,以磷钼蓝反应为基础的薄层树脂相吸光光度法测定钼。此方法灵敏度较高(ε705=8.1×104L·mol-1·cm-1),比液相光度法提高10倍,精密度理想(钼浓度为20μg/25ml,n=6),RSD为2.8%。应用此法测定天然水中钼,线性范围为0～18μg·ml-1,回收率为97%～102%。     

分光光度法联测铝电解质中二氧化硅和三氧化二铁的含量

采用高温熔融和硫酸冒烟处理样品,用分光光度法联测法测定铝电解质中二氧化硅和三氧化二铁含量的方法。在HNO3介质中,用硅钼蓝光度法测铝电解质中SiO2,ε700=2.1×104L.mol-1.cm-1。实验表明,SiO2的浓度在0~1.75μg/mL范围内时符合比尔定律。在HAc-NaAc(Ph=4.9)的介质中,用邻菲啰啉光度法测铝电解质中Fe2O3,ε510=1.1×104L.mol-1.cm-1。实验表明,Fe2O3的在0.0~2.5μg/mL范围内时符合比尔定律。SiO2加标回收率为98%~104%,Fe2O3加标回收率为94.8%~104.8%。本方法测定铝电解质中的SiO2和Fe2O3具有选择性好、灵敏度高和准确可靠等特点,并获得了较满意的分析结果,为更加科学的调整电解质分子比提供了基础数据。     

锗-苯基荧光酮-吐温-80-明胶增溶光度法测定人发中微量锗

在盐酸介质中,以苯基荧光酮为显色剂,吐温-80为表面活性剂,明胶为稳定剂,用增溶胶束分光光度法测定微量锗。探讨了测定微量锗的最佳显色条件和光度测定条件。配合物的最大吸收位于510 nm波长处,锗含量在0.5~10μg/50 mL范围内符合比耳定律,其摩尔吸光系数ε=1.18×105L.mol-1.cm-1,具有较高的灵敏度和选择性,用于人发中锗含量的测定,测定结果的RSD小于0.9%,加标回收率在95.9%~105.9%。     

邻苯二胺分光光度法测定茶汤中的咖啡因

提出了采用邻苯二胺分光光度法测定茶汤中的咖啡因。它是基于咖啡因在加热以及酸性条件下,能与邻苯二胺反应生成浅橙黄色苯并杂环类物质,此物质在488 nm处有最大吸收。该方法线性范围为4.0~25.0μg/mL,表观摩尔吸收系数ε=6.19×104L.mol-1.cm-1,相对标准偏差RSD=1.2%,回收率为100%~105%。已用于茶汤中咖啡因的测定。     

巯基葡聚糖凝胶分离富集-光度法测定微量有机锗和无机锗

研究了巯基葡聚糖凝胶分离富集 光度法测定微量有机锗和无机锗。在HCl介质中,在抗坏血酸(Vc)、溴化十六烷基三甲基胺存在下锗与2,4 二甲氧基苯基荧光酮形成有色络合物,其ε=1.12×105L·mol-1·cm-1,锗浓度在0～12μg/25mL范围内符合比耳定律。方法可用于多种样品中痕量有机锗和无机锗的测定,结果令人满意。     

镁及镁合金中微量磷的测定方法研究

磷与钼酸铵形成磷钼杂多酸络幌物,用乙酸丁酯萃取分离,用SnCl2还原反萃取后借磷钼蓝光度法测定镁及镁合金中微量磷。在波长700 nm处工作曲线线性范围0~1.5μg/mL,相关系数为0.9995,络合物表观摩尔吸光系数ε=1.45×104L.mol-1.cm-1,相对标准偏差在1.40%~3.10%之间,加标回收率在99.3%~101.0%之间,本法与ICP法相对照结果比较满意。     

甲基橙褪色光度法快速测定食品中亚硝酸根含量

基于在室温下HOAc介质中亚硝酸能使甲基橙褪色的原理,建立了测定亚硝酸根的快速褪色光度方法。通过正交试验优化了方法的测定条件,在最佳条件下,方法的表观摩尔吸光系数分别为4ε16=1.1×104L.mol-1.cm-1,5ε06=5.2×104L.mol-1.cm-1;线性范围及回归方程分别为5.0~600.0 mg.L-1、ΔA416=0.000 344 6c+0.002 23、r=0.999 6(416 nm);1.0~300.0 mg.L-1、ΔA506=0.000 147c+0.021 02、r=0.985 3(506 nm);检出限为5.0 mg.L-1(416 nm)1、.0 mg.L-1(506 nm)。用于食物中亚硝酸根的测定,RSD为0.2%~4.2%,加标回收率在98%~103%。经t检验,其测定结果与国标GB/T 5009.33-1996方法的测定结果一致。     

邻菲口罗啉-Fe(Ⅱ)体系光度法间接测定头孢噻肟钠

基于头孢噻肟钠在0.3 mol/L NaOH溶液中沸水浴降解产物具有还原性,在酸性介质中可将Fe(Ⅲ)还原为Fe(Ⅱ),邻菲口罗啉能与所生成的Fe(Ⅱ)显色生成红色络合物,最大吸收波长λ=508 nm;表观摩尔吸光系数ε=1.1×104L.mol-1.cm-1;头孢噻肟钠在0.4~80μg/mL范围内呈良好的线性关系;线性回归方程为A=-0.00204 0.01989ρ(μg/mL);线性相关系数r=0.9998;检出限为0.18μg/mL;RSD为1.2%(5.0μg/mL,n=11);平均回收率为99%。初步探讨了反应机理,并优化了对头孢噻肟钠的测定条件。     

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%.     

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

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.     

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.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.