电感耦合等离子发射光谱法测定镍铁中Si,Mn,P,Ni

建立ICP–AES法测定新型材料镍铁中的Si,Mn,P,Ni元素的方法。考察了镍铁基体和共存元素对测定结果的影响。通过基体匹配消除基体干扰,确定各待测元素谱线为Mn 293.930 nm,P 178.280 nm,Ni 231.604 nm,Si251.611 nm。Si,Mn,P,Ni的检出限分别为0.06,0.04,0.08,0.04 mg/L,测定结果的相对标准偏差均小于5%(n=11),加标回收率在95%~105%之间。该方法操作简便、测定结果准确可靠,可用于镍铁中Si,Mn,P,Ni的含量测定。     

ICP–AES法测定超高强度钢中的Al,Mn,Si,Ti

建立ICP–AES法测定超高强度钢中Al,Mn,Si,Ti 4种杂质元素的分析方法。研究了溶解条件试验及共存元素对4种分析元素的光谱干扰的情况,选择了Al 394.401 nm,Mn 257.610 nm,Si 251.611 nm,Ti 334.941 nm作为分析谱线。在选定的实验条件下,Al,Mn,Si,Ti的含量在0.001%~0.2%的范围内有良好的线性关系,相关系数均大于0.993,Al,Mn,Si,Ti的检出限为0.000 1~0.003 5 mg/L,加标回收率为94%~120%,测定结果的相对标准偏差小于10%(n=8)。该方法准确、快速,可用于超高强度钢中Al,Mn,Si,Ti的含量测定。     

ICP-AES法测定AuNiGd合金中的Ni、Gd、Pd、Fe和Bi

报道了采用ICP-AES法测定AuNiGd合金中Ni、 Gd、 Pd、 Fe、 Bi.对测定元素的波长、测定条件进行了选择;考察了基体和无机酸对测定的影响;在优化条件下,对试样进行测定,其相对标准偏差(n＝15) Ni 1.6%、 Gd 1.8%、 Pd 13%、 Fe 4.9%、 Bi 13%;回收率 Ni 98%～105%、 Gd 97%～99%、 Pd 101%～105%、 Fe 98%～104%、 Bi 104%～106%.     

电感耦合等离子体原子发射光谱(ICP-AES)法测定镧玻璃废粉中稀土元素总量及配分量

建立了电感耦合等离子体原子发射光谱(ICP-AES)法测定镧玻璃废粉中稀土元素总量和配分量的分析方法。样品经碱熔融后分离硅、铝等元素及钠盐,用硝酸和高氯酸破坏滤纸和溶解沉淀,用ICP-AES法测定稀土元素总量和配分量。讨论了溶解样品条件、共存元素干扰等影响测定的各种因素。实际样品的稀土总量与草酸盐重量法测定结果一致,配分量与X-射线荧光光谱(XRF)法、电感耦合等离子体质谱(ICP-MS)法测定结果一致。RSD(n=11)在0.15%~1.1%,加标回收率为97%~105%。测定范围为:La_2O_3/REO(80%~98%);CeO_2/REO(2%~20%);REO(16%~70%)。方法能快速准确地测定镧玻璃废粉中稀土元素总量及配分量。     

微波消解-ICP-AES法测定拟薄水铝石中11种微量或痕量杂质元素

采用微波消解,ICP-AES法测定了拟薄水铝石中Si,Fe,Na,K,Ca,Mg,Zn,Ti,V,P,Li等11种微量和痕量杂质元素含量。样品用王水溶解,在200℃密闭消解30 min,冷却定容后进行测定。用各元素标准溶液绘制校准曲线,用高纯铝基体匹配校正基体效应。在选定的仪器工作条件下,11种被测杂质元素的检出限范围0.0024~0.42μg/m L,当杂质元素含量大于0.001%时,本法测定值与XRF法和AAS法的测定值相符,不同元素测定值的相对标准偏差(n=10)在0.70%~4.8%之间。     

电感耦合等离子体发射光谱测定稀土铝合金中稀土和非稀土元素

本工作用 ICP-AES 法测定稀土-6063变形铝合金中 La、Ce、Pr、Nd、Sm、Gd、Fe、Mg、Ti、Zn,Cu 和 Mn,本方法不用化学分离,可一次同时测定这些元素,并做了 ICP光源参数、基体量变化、酸度(HCl)变化、稀土总量变化、共存元素 Fe 和 Mg 量的变化对被测元素的影响。本方法速度快、准确度高(除 Cu 稍差)。回收率91.0～110.0%,相对标准偏差±1.4～8.0%。     

La_(0.63)Gd_(0.2)Mg_(0.17)Ni_(3.2-x)Co_(0.3)Al_x(x=0～0.4)储氢合金的微观组织和电化学性能

采用真空感应熔炼方法制备了La0.83Mg0.17Ni3.1Co0.3Al0.1和La0.63Gd0.2Mg0.17Ni3.2-xCo0.3Alx(x=0~0.4)贮氢合金,并在氩气气氛900℃进行退火处理。通过X射线衍射(XRD)、显微电子探针(EPMA)分析方法和电化学测试分析研究了Gd和Al元素对合金微观组织和电化学性能的影响。研究结果表明,该系列合金退火组织主要由Ce2Ni7/Gd2Co7型、Pr5Co19型、PuNi3型和CaCu5型相组成;Gd元素的加入使合金中CaCu5型相明显减少,Ce2Ni7型/Gd2Co7型相显著增加,x=0.1时其相丰度达到81.2%;随Al含量x不断增加,合金中CaCu5型相丰度逐渐增多,当x=0.1~0.2时,CaCu5型相丰度为4%~5%,x=0.4时,其相丰度达到66.65%。电化学测试分析表明,Gd和Al元素对合金电极活化性能影响不大,当x=0.1时,含Gd合金电极放电容量达到最大值391 mAh.g-1,随Al含量x进一步增加,合金电极放电容量降低。含Gd和加入适量的Al元素可使合金电极循环稳定性得到明显提高,当Al含量x=0.1,0.2时,经100次充放电循环后其电极容量保持率S100分别为93.7%和90.1%,其中La0.63Gd0.2Mg0.17Ni3.1Co0.3Al0.1合金具有最好的综合电化学性能。     

NdFeB合金中13种非稀土元素的ICP-AES分析方法的研究

建立了NdFeB合金中Al、Cu、Co、Mg、Si、Ca、Ti、V、Cr、Mn、Ni、Zn、Ga等13种微量及常量元素的ICP-AES分析方法,选用5 g/L及1 g/L的进样浓度,以准基体匹配法校正基体效应的影响。考查了共存元素的光谱干扰,选择了测量谱线;考查了合金主成分含量有所波动时对测定产生的影响,误差在-1.8%～3.2%,可忽略不计。方法的测定下限在0.0005%～0.0033%,加标回收率在95.3%～103.4%;与ICP-MS法和分光光度法的比对结果良好。对4个NdFeB合金样品进行了测量精密度统计(n=11),RSD在0.8%～5.1%。     

电感耦合等离子体原子发射光谱(ICP-AES)法测定金属铬中Fe、Al、Si

采用盐酸溶样,标准加入法消除基体铬的干扰,利用电感耦合等离子体原子发射光谱(ICPAES)法测定金属铬中Fe、Al、Si。对仪器参数以及被测元素的谱线选择进行了讨论,在选定最佳条件下,对标准样品金属铬进行测定,探讨了检测方法中标准曲线线性相关性、检出限、精密度及加标回收率等指标,发现各元素的测定值与认定值基本一致,测量相对标准偏差均小于1%(n=7),加标回收率在96.9%~101%。方法实用性强,已经成功应用于金属铬中杂质元素的检测。     

微波消解–电感耦合等离子体发射光谱法测定DD6单晶合金中铝、铬、钴

建立电感耦合等离子体发射光谱法测定DD6单晶高温合金中铝、铬、钴元素含量的方法。采用密闭微波消解法对样品进行前处理,利用模拟溶液分别考察基体元素和共存元素的光谱干扰及非光谱干扰对测定结果的影响,确定了铝、铬、钴的分析谱线分别为394.401,267.716,228.616 nm,通过基体匹配法对非光谱干扰进行补偿。待测元素在各自的质量浓度范围内与光谱强度呈良好的线性关系,相关系数均为0.9999,铝、铬、钴的检出限分别为0.110,0.018,0.003 μg/mL。测定结果的相对标准偏差为0.99%~1.21%(n=11),铝、铬、钴的加标回收率在分别为96.45%~103.69%,98.20%~99.40%,100.22%~102.85%。该方法简便、快速,具有较高的准确度,适用于镍基单晶高温合金中铝、铬、钴元素的测定。     

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.     

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.     

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.     

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.     

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.     

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.