火焰原子吸收法测定钴基合金喷粉中铁的含量

建立了一种用空气-乙炔火焰原子吸收法测定钴基合金喷粉中铁含量的分析方法,探讨了硅对铁测定的干扰机理,对用氯化钙作为硅干扰铁测定的释放剂进行了试验。该方法测定铁含量的线性范围为O～10mg/L,线性相关系数为0．9980。对含铁2.29％的钴基合金喷粉标准样品进行测定,测定结果的相对标准偏差为2．28％(n=6)．加标回收率为95．0％～104.0％。     

紫尿酸双波长叠加光度法测定水中微量铁

在碱性介质中,铁（Ⅱ）与紫尿酸发生显色反应形成一种蓝色配阴离子,该配阴离子具有两个吸收峰,分别位于630nm和350nm,吸光度A630,A350之和△A与铁（Ⅱ）的含量在0-2μg／mL范围内线性关系良好,据此建立了测定微量铁的紫尿酸双波长叠加光度法,该法用于水中微量铁的测定,测定结果与火焰原子吸收法（FAAS）相吻合,加标回收率为98％-102％,测定结果的相对标准偏差为1．2％-2．9％（n=5）。     

银锌电池材料用无甘油玻璃纸中铜铁含量的测定

采用空气-乙炔火焰原子吸收光谱法连续测定银锌电池材料用无甘油玻璃纸中铜、铁含量。介绍铜铁最佳测定条件及呈良好线性关系的浓度范围,并对样品消化处理条件及在样品测定中的干扰因素进行了考察。样品测定结果的相对标准偏差均小于1．0％（n=10）,加标回收率为98．0％～98．5％。该法适合生产现场控制分析和样品系统分析。     

铁-联吡啶体系化学振荡的研究及其在价态分析中的应用

试验发现,铁-联吡啶体系中存在化学振荡,初步探讨了该体系的化学振荡规律,并找出氟化铵为有效的振荡抑制剂。加入抑制剂后,在Fe（Ⅲ）存在下,铁-联吡啶分光光度法能准确测定Fe（Ⅱ）。方法用于人工样品中铁的价态分析,测得Fe（Ⅱ）的回收率为99．0％～99．7％,Fe（Ⅲ）的回收率为99．5％～103．0％。     

催化动力光度法测定痕量铁

基于稀硝酸介质中痕量铁(Ⅲ)对过氧化氢氧化甲基橙褪色反应的催化作用,建立了测定痕量铁(Ⅲ)的动力学光度法。应用了单纯形优化法作条件试验,方法的灵敏度为0．015 μg· L-1,线性范围为0-9．6 μg·L-1。用于测定活性碳中痕量铁(Ⅲ),回收率在99％至105％之间。     

电位滴定法测定弹性合金中的高含量钴

采用电位滴定法测定弹性合金中的钴元素。探讨了弹性合金中基体元素铁,主量元素如铬、锰、钼、镍、钨等对钴元素测定的干扰情况,确定了合适的样品处理方法,同时进行了铁氰化钾用量及滴定溶液温度控制等条件试验。测定结果的相对标准偏差为0．19％-0．28％（n=8）,回收率为99．9％-100．8％。该方法可以满足弹性合金中高含量钴元素的测定要求。     

ICP-AES法测定锡精矿中锡、铜、铅、铁的含量

建立了过氧化钠熔融分解样品、电感耦合等离子发射光谱法（ICP-AES）测定锡精矿中锡、铜、铅、铁的新方法。对试样分解方法、过氧化钠用量、元素分析谱线等进行了讨论。选择过氧化钠用量为2．0g,样品熔融温度为850~C,锡、铜、铅、铁分析谱线分别为189．991,324．754,220．353,259．940nm。将该方法应用于标准样品（BY0107—1）中Sn,Cu,Pb,Fe的测定,待测元素的回收率在92．0％-101．6％之间,检出限为分别为0．006,0．002,0．005,0．001μg／mL,测定结果的相对标准偏差为0．16％～2．11％（n=5）。     

火焰原子吸收光谱法连续测定香蕉中的铜铁锌锰

研究了香蕉中的金属元素的含量和火焰原子吸收光谱法在同一体系中测定香蕉中微量元素铜、铁、锌、锰的方法，考察了硝酸、过氧化氢的不同用量以及消化时间长短的影响和在同一体系中铜、铁、锌、锰的相互干扰情况。在选定条件下铜检测限为0．064μg／mL，铁为0．275μg／mL，锌为0．157μg／mL，锰为0．187μg／mL，相对标准偏差为1．9％-4．7％，回收率为92．3％-105．0％。     

原子吸收光谱法测定三醋酸纤维素膜中铜铁

运用空气-乙炔火焰原子吸收光谱法同时测定银锌电池三醋酸纤维素膜中铜铁含量，并对测定条件和干扰因素进行了综合分析．该测定方法具有很好的灵敏度，干扰少，选择性和重现性好等优点．测定样品铜铁含量的相对标准偏差均小于1．0％．标准加入回收率均在97．3％-98．8％范围内．完全适用于银锌电池三醋酸纤维素膜中铜铁含量的控制和样品系统分析．     

火焰原子吸收分光光度法测定铜合金中的铁

研究了火焰原子吸收分光光度法测定铜合金中铁含量的方法,对仪器工作条件如灯电流、光谱通带、空气和乙炔流量进行了分析。铁的质量浓度在0-5mg／L内与吸光度呈良好的线性关系,线性方程为A：0．03179c＋0．004098,相关系数,r=0．9996,检出限为0．009mg／L。用该方法对4种铜合金标准物质进行测定,测定结果与标准值相符,相对标准偏差分别为0．54％,0．78％,0．10％,2．07％0=6）。     

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.     

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.     

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.     

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.     

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.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.