激光剥蚀-电感耦合等离子体质谱法测定多晶硅中杂质元素

采用激光剥蚀固体进样技术结合电感耦合等离子体质谱法测定了多晶硅中的元素B、Cu和Zn。考察了该三种杂质元素在多晶硅样品不同深度层面和同一深度层面的分布情况;尝试了采用硅基体信号归一化的方法计算了测定元素的含量。结果表明,杂质元素B、Cu和Zn在多晶硅材料中分布均匀,且测定结果与辉光放电质谱法的测定结果相吻合。这一方法可用于判别多晶硅表面的污染情况,以及杂质元素在多晶硅材料内部分布的均匀性。     

钢铁中硫的测定方法研究进展

综述了从1979-2009年间测定钢铁中硫元素分析方法的研究进展。钢铁材料中硫元素的主要分析方法包括红外吸收光谱法、原子发射光谱法、离子色谱法、质谱法、电化学方法、分光光度法、滴定分析法、重量法和原子荧光光谱法;并对钢铁中硫元素的分析方法进行了展望(引用文献54篇)。     

中子活化分析法测定金属镓中痕量杂质元素

中子活化分析法具有灵敏度高、准确度好、精密度高的特点,而且可以避免试剂和环境污染,同一份试样可同时进行多元素分析。因此一直是高纯材料中测定痕量杂质元素最有效的分析方法之一。在国家标准高纯镓分析方法的起草工作中,为了校验其他分析方法,用中子活化分析法测定了金属镓中铁、锌、铟、汞、锡、钙6种杂质元素的含量。     

高纯硅中痕量元素分析方法研究进展

综述了从1980-2012年间测定高纯硅中痕量元素分析方法的研究进展。高纯硅中痕量元素的主要分析方法包括红外光谱法、原子发射光谱法、原子吸收光谱法、X射线荧光光谱法、极谱法、离子探针与离子色谱法、二次离子质谱法、辉光放电质谱法、电感耦合等离子体质谱法等;并对高纯硅中痕量元素的分析方法进行了展望(引用文献59篇)。     

GD-MS法和ICP-MS法测定高纯铌中痕量元素

采用辉光放电质谱法(GD-MS)对高纯铌中Ta,Mo,W等痕量杂质元素进行了测试,并对GD-MS工作参数进行了优化,部分元素与采用电感耦合等离子体质谱法(ICP-MS)定量分析的结果进行比较,对某些元素含量差别较大的原因进行了分析,论述了Element GD辉光放电质谱仪的特点及其在痕量杂质分析上的优势。     

辉光放电质谱法测定高纯材料中痕量硫杂质

准确测定并控制材料中杂质元素含量是发挥高纯材料性能不可或缺的环节。辉光放电质谱法(GDMS)是准确、快速、高灵敏分析高纯材料中痕量及超痕量硫的理想方法。对GDMS分析高纯铜和镍基高温合金中痕量硫的质谱干扰进行了讨论,优化了放电电流和放电电压,采用多种标准物质对硫的相对灵敏度因子(RSF)进行了校准和验证,并与二次离子质谱法(SIMS)进行分析结果比对,验证了GDMS定量分析结果的准确性和可靠性。     

钛基材料中元素分析方法研究进展

综述了钛基材料中组分元素测定方法的近年研究进展情况,涉及分析方法有原子发射光谱法、原子吸收光谱法、分光光度法、滴定法、X射线荧光光谱法、质谱法、红外/热导法等(引用文献73篇)。     

微型柱分离-ICP-MS法测定高纯氧化铽中14个稀土杂质元素

研究了微型柱分离 电感耦合等离子质谱法(ICP MS)测定高纯Tb4O7中痕量Lu的方法,采用Cyanex272负载树脂微型分离柱,选定了分离大量Tb4O7基体的实验条件,分离周期为40min。建立了微型柱分离Tb后测定Lu以及内标补偿法直接测定其它稀土杂质的高纯Tb4O7中14个稀土杂质元素的ICP MS分析方法。方法检出限为0.003～0.10μg g,加标回收率为86.6%～114%,相对标准偏差为1.1%～18%。方法可满足快速测定99.999%Tb4O7中14个稀土杂质元素的要求。     

辉光放电质谱法测定超高纯铜溅射靶材中痕量杂质元素及其相对灵敏度因子的求取北大核心CSCD

通过选择合适的同位素及分辨率,提出了辉光放电质谱法(GDMS)测定超高纯铜溅射靶材中39种痕量杂质元素的分析方法。对辉光放电过程中的参数进行了优化,条件如下:放电气体流量为450 mL·min^(-1),放电电流为2.00 mA,预溅射时间为20 min。由于高纯铜的GDMS标准样品极难获得,为提高痕量杂质元素的检测准确度,在现有的标准样品条件下,利用高纯铜标准样品只获得了与基体匹配的21种杂质元素的相对灵敏度因子(RSF),其余18种杂质元素的RSF只能按照仪器自带的标准RSF进行计算。参照美国材料与试验协会的标准ASTM F1593-08(2016)的TypeⅢ中的第2种方法计算33种杂质元素的检出限,而其他6种主要杂质元素因其含量高于仪器噪声水平而无法用此法得到检出限。用GDMS对超高纯铜溅射靶材样品进行了检测,主要杂质元素为硅、磷、硫、氯、铁、银,检出量为0.015~0.082μg·g^(-1),杂质总量小于1μg·g^(-1)。除锌、碲、金的检出限在10 ng·g^(-1)级外,其余元素的检出限能够达到ng·g^(-1)级,其中钍、铀的检出限甚至达到了0.1 ng·g^(-1)级,说明方法能够满足GB/T 26017-2010中的6N(99.9999%)超高纯铜溅射靶材的检测要求。     

直流电弧光谱法测定石墨材料中12种杂质元素

建立了直流电弧光谱法测定石墨材料中12种杂质元素含量的分析方法。通过实验优化选择了适用的激发条件和分析谱线,对石墨材料中Mg,Co,Cr,Ni,V,Ti,Fe,Mn,Cu,Al,Si,Ca12种杂质元素进行检测。在最优条件下,方法的定量限范围在0.6~6.1μg/g之间,回收率在94%~110%之间,相对标准偏差(RSD)介于5%~14%。与辉光放电质谱检测结果比对,结果基本一致。本方法适用于石墨材料中杂质元素的快速测定。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

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.     

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%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

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.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

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.