电感耦合等离子体质谱测定高纯金属钐中25种杂质元素

研究建立了电感耦合等离子体质谱(ICP—MS)测定高纯金属钐中14种稀土及11种非稀土杂质的测定方法。考察了钐基体对杂质元素测定的各种干扰影响。对无干扰的杂质元素,采取了直接测量的方式;对有干扰的元素(Nd、Eu、Dy、Ho、Er、Tm),采用标准加入法的方式进行测定。选择内标元素Sc和Cs,有效补偿了由于基体效应带来的测量偏差。方法的检出限为0．012～83μg／L．加标回收率为88．6％～108．0％．测定精密度(RSD)为0．55％～2．53％,方法可满足99．9％纯度的金属钐中朵质元素的分析测定。     

微柱分离-ICP-MS测定高纯氧化钆中14种稀土杂质

研究了采用自制微柱分离装置分离Gd2O3基体的条件。99．9％以上基体被分离，分离周期为36min。建立了高纯Gd2O3中分离Gd后测定Yb、Lu以及内标补偿法直接测定其它12种稀土杂质的ICP—MS分析方法.定量下限为0．08～0．80μg／g，加标回收率为85％～115％，相对标准偏差为1．1％～8．5％、方法可满足快速测定99．999％ Gd2O3中14种稀土杂质的要求。     

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。     

等离子体质谱多内标法测定金属铒中多种痕量元素

本方法采用ICP—MS法同时测定高纯金属铒中14个稀土元素和15种非稀土元素杂质，确定了合适的样品稀释浓度，采用Sc、In、Cs、Tl4个内标，杂质元素的检出限在0．04～16μg／g之间，样品的加标回收率在86％～105％之间，能够满足4N金属铒产品的检测需求。     

电感耦合等离子体质谱法测定高纯金属铋中痕量杂质元素

采用电感耦合等离子体质谱法测定了高纯金属铋中14种痕量杂质元素。考察了基体效应对测定元素的干扰影响,通过铋基体元素的分离和以Sc、In、Eu作为内标,有效克服了干扰现象。方法的检出限在0．1～4．7ng/mL;精密度在1．4％～5．0％;加标回收率在89％～114％范围。本法可满足99．999％以上金属铋中痕量杂质测定的要求。     

感耦等离子体质谱法测定高纯氧化镥中14个痕量稀土杂质

本文报道了用感耦等离子体质谱法（ＩＣＰ－ＭＳ）测定高纯氧化镥中１４个稀土杂质的方法。镥基体对测定元素无谱线干扰，但对测定信号产生显著抑制作用。加入内标后有效地补偿了这种基体抑制效应，方法检出限为０．００５～０．０３ｎｇ／ｍＬ。样品加标为０．０１μｇ时，回收率为９０％～１０３％。精密度（ＲＳＤ）为１．４％～４．２％。方法简单，不需分离富集，样品消耗量少（１０ｍｇ）。１４个稀土元素的总测定下限（１０）可达０．５８μｇ／ｇ可直接测定纯度为９９．９％～９９．９９９９％的氧化镥中稀土杂质。     

新型D-238树脂色层分离-ICP/AES法测定4N光学级La_2O_3中Co、Cr、Cu、Fe、Mn、Ni、Pb和V

本文采用新型D-238树脂,使待测元素与基体La分离。用6mol/L HNO_3解脱非稀土杂质,ICP-AES法同时测定4N光学级La_2O_3中8个痕量非稀土杂质。方法的检出限为0.2～2.8μg/g,相对标准偏差<8%。     

ICP-MS 法测定高纯氧化铕中稀土杂质的研究

深入考察了ＩＣＰ－ＭＳ法测定高纯氧化铕时基体对稀土杂质测定的影响,研究了Ｐ５０７萃淋树脂分离大量基体Ｅｕ２Ｏ３的实验条件,建立了采用内标补偿直接测定大部分稀土杂质和经Ｐ５０７萃淋树脂分离基体后测定被干扰离子Ｔｍ相结合的高纯Ｅｕ２Ｏ３中稀土杂质的ＩＣＰ－ＭＳ分析方法。方法检出限为０．００５～０．０２１μｇ／Ｌ,加标回收率为８４％～１１２％。ＲＳＤ为１．４％～８．１％。本法适用于质量分数为９９．９９％～９９．９９９９％的高纯Ｅｕ２Ｏ３中稀土杂质的分析。     

膜去溶-ICP-MS法测定高纯Eu_2O_3中14种痕量稀土杂质

研究了不需基体分离,膜去溶-ICP-MS法直接测定高纯Eu2O3中的14种痕量稀土杂质的分析方法。讨论了Eu基体产生的多原子离子对被测元素的质谱干扰。使用膜去溶后,待测元素灵敏度提高3倍左右,EuO/Eu产率从去溶前的0.016%降低为0.0007%。建立了Tm的数学校正方程,通过膜去溶结合数学校正可将Eu基体对Tm干扰完全消除。14种稀土杂质的检出限和(∑RE)为70 ng/L,测定下限和(∑RE)为0.54μg/g。对6N高纯Eu2O3样品进行了分析,样品回收率为96%~109%,RSD小于10%。所建立的方法对Eu2O3标准样品的测定结果与国家标准方法测定结果相一致。     

微型柱在线分离-ICP-MS法测定高纯氧化铕中的14个稀土杂质

研究了微型柱在线分离-电感耦合等离子质谱法（ICP-MS）测定高纯Eu2O3中痕量Tm的方法，研制了Cyanex272负载树脂微型分离柱，优化了分离Eu2O3基体的实验条件，在线分离测定时间为25min。建立了在线柱分离测定Tm，内标补偿法直接测定其余稀土杂质的高纯Eu2O3中14个稀土杂质的ICP-MS分析方法。方法检出限为0.01μg/g-0.15μg/g，加标回收率为91.5%-110%,相对标准偏差为1.7%-4.9%。可满足快速测定99.999%Eu2O3中14个稀土杂质的要求。     

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%.     

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.     

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.     

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.     

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.