人工神经网络分光光度法同时测定钼和铬

在钼，铬－二溴邻硝基苯基荧光酮－ＣＴＭＡＢ显色体系中，应用三层ＡＮＮ－ＢＰ网络解析钼和铬的吸收光谱，不经分离分光光度法同时测定钼和铬。钼和铬的表观摩尔吸光系数分别为ε５４５＝ ６．４８×１０４Ｌ·ｍ ｏｌ－ １·ｃｍ － １，ε５４７＝ １．５４×１０４Ｌ·ｍ ｏｌ－ １·ｃｍ － １。对合成样品和合金钢中钼和铬进行了同时测定，结果满意。使用改进的ＢＰ算法，避免了神经网络学习过程中可能产生的麻痹现象。提出了目标向量的简单变换方法及便于网络参数选择的收敛评价函数。     

直接进样-电感耦合等离子体质谱法测定特殊医用配方食品中铬、钼和硒

本文采用1%四甲基氢氧化铵溶液溶解样品,单氦碰撞池模式直接分析特殊医用配方食品中的铬、钼和硒。研究表明:铬、钼和硒在质量浓度2.0~50.0μg/L范围内呈良好的线性关系,铬、钼、硒的检出限分别为0.012、0.009和0.009mg/kg;加标回收率在94%~117%之间,相对标准偏差在1.47%~5.78%之间。本方法对NIST 1849a和FAPAS T07216QC标准物质中铬、钼和硒的测定值与参考值相符。该方法操作简单、快速,适合特殊医用配方食品中铬、钼和硒的同时测定。     

微波消解-电感耦合等离子体质谱法测定乳制品中铬、钼和硒

本文采用HNO3密闭微波消解样品,手动添加内标碲,电感耦合等离子体质谱(ICP-MS)法分析乳制品中的铬、钼和硒。研究表明:铬和钼在0.8~20.0μg/L质量浓度范围内,硒在0.4~10.0μg/L质量浓度范围内,呈良好的线性关系。方法检出限分别为:铬0.012mg/kg、钼0.009mg/kg和硒0.009mg/kg;加标回收率在86%~115%之间,相对标准偏差在1.46%~6.81%(n=8)之间。该方法操作简单,适合乳制品中铬、钼和硒的同时测定。     

ICP–OES法测定锰钢中的铬、钼、磷

采用电感耦合等离子体发射光谱法测定锰钢中的铬、钼、磷。以盐酸–硝酸混合酸处理试样,通过选择元素的分析线来优化测试条件,利用基体匹配法消除基体干扰。结果表明,铬、钼、磷3种元素测定结果的相对标准偏差为0.86%~2.31%,加标回收率为96.7%~103.2%。该法能够满足日常分析对锰钢中铬、钼、磷含量测定的需要。     

过渡金属氨基酸席夫碱配合物的合成

合成了6个过渡金属氨基酸席夫碱配合物——L-酪氨酸缩水杨醛合铬(钼),L-赖氨酸缩水杨醛合铬(钼),DL-α-丙氨酸缩水杨醛合铬(钼),其结构经UV,IR和元素分析表征。UV测定结果表明,配合物均可与DNA发生插入作用。     

直读光谱法测定合金工具钢中铬、锰和钼

建立了ARL-4460直读光谱仪对Cr12、Cr12MoV中铬、锰、钼元素的快速检测方法。使用基体铁作为内标元素,测定标准样品中铬、锰、钼元素的相对强度,减少了外界电压不稳对绝对强度稳定性的影响;由于标准样品中基体铁含量不同,为减少内标元素含量的变化对工作曲线相关系数和估计标准差的影响,使用相对含量校正工作曲线。在优化的实验条件下,试样中三种元素的相对标准偏差分别为0.68%、0.79%和1.7%(n=11)。测定结果与化学分析方法测定结果一致,可实现合金工具钢中铬、锰和钼的快速检测。     

高铬合金铸铁中铬、铜、钼、镍、锰的快速联合测定

耐磨高铬合金铸铁以其良好的耐磨、耐蚀及耐热性能，得到了广泛应用。因该类样品不易溶解，单个元素分析难以满足快速分析的需要。本文在文献的基础上，采用王水溶解、硫一磷混酸高温下滴加硝酸氧化发烟以破坏碳化物。控制试验条件，对其中的铬、铜、镍、钼、锰采用联合测定，减少了重复操作，提高了分析速度。本方法应用于耐磨高铬合金铸铁中铬、铜、钼、镍、锰的联合测定，结果满意。     

微波消解–ICP–MS法测定格隆溴铵注射液中的铬、镍、钼

建立了电感耦合等离子体质谱法测定格隆溴铵注射液中铬、镍、钼3种残留金属元素的方法。分别在0,500,1 200 W功率下,样品采用硝酸和过氧化氢混合溶液微波消解,在选定的仪器工作条件下测定。铬、镍、钼的质量浓度在5～200 ng/mL范围内具有良好的线性关系,相关系数不小于0.995,方法检出限为0.22～0.49 ng/mL,定量限为1.08～2.46 ng/mL。测定结果的相对标准偏差为1.4%～3.0%(n=11),样品加标回收率为92.88%～111.94%。该方法操作简单、快速,结果准确、可靠,适用于格隆溴铵注射液中铬、镍、钼的测定。     

电感耦合等离子体原子发射光谱法测定不锈钢中8种合金元素

采用硝酸-盐酸-水(1+3+6)混合酸溶液溶解不锈钢样品,用电感耦合等离子体原子发射光谱法同时测定试样溶液中铬、镍、铜、锰、磷、硅、钼和钛等8种合金元素。选择钇元素作为内标元素,选择波长为357.869,231.604,327.396,257.610,178.284,251.611,202.030,337.280 nm8条谱线依次作为铬、镍、铜、锰、磷、硅、钼和钛的分析线。方法用于分析了12种标准物质,测定值同证书值一致,各元素的相对标准偏差(n=7)均小于5.5%。     

大肠癌与溃疡性结肠炎患者血清微量元素测定

用ＩＣＰ－ＡＥＳ方法，对３０例大肠癌，２６例溃疡性结肠炎进行血清钼，锌，铬铁，铜，锰，铅，铝，硒，铋，钡，钛，钴，钒等微量元素测定，并与２０例健康者对照。结果显示大肠癌组血清钼，锌，铬，低于对照组钼，锌，铬，Ｐ分别〈０．０１，〈０．０５，〈０．０５；溃疡性结肠炎组钼低于对照组，Ｐ〈０．０５。提示微量元素代谢异常可能直接影响酶系统，使自由基失控，体内促氧化和抗氧化平衡失调，促使肿瘤的发生。     

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.