电感耦合等离子体原子发射光谱(ICP-AES)法测定铝铍中间合金中的铍

通过对铍的自吸效应和光谱干扰研究,选取了Be(Ⅱ)313.1nm作为分析线,建立了铝铍合金中测定铍元素含量的电感耦合等离子体原子发射光谱(ICP-AES)法。实验结果表明,谱线Be(Ⅱ)313.0nm的线性范围达到20μg/mL,谱线Be(Ⅱ)3 131nm的线性范围可达30μg/mL,当溶液中铍元素的浓度超过线性范围时,两条谱线的工作曲线发生弯曲,产生明显的自吸效应,样品分析过程中避免使用有自吸效应的谱线,可以大大提高分析结果的准确性;样品中主要杂质元素和基体对铍的谱线不产生光谱干扰。方法中铍的检出限为0.000 4%。铍的质量浓度在1.0~15μg/mL时,工作曲线的线性回归方程为y=265.101 0x+0.45,相关系数R=0.999 645。按实验方法分别对铝铍合金样品和合成的模拟标准样品进行回收率和精密度实验,标准加入回收率在101%~103%,相对标准偏差在0.58%~0.98%。方法能够准确快速地分析铝铍中间合金中铍的含量。     

ICP-AES法测定不锈钢中高含量镍和铬的光谱干扰和校正

使用HNO3,HF,HCl O4溶解不锈钢样品,以Ni 231.6 nm,Cr 267.7 nm作为分析谱线,以干扰系数法校正Fe对Ni和Cr的光谱干扰,建立了ICP-AES法测定不锈钢中高含量Ni和Cr的方法。通过测定不同铁基体浓度下Ni和Cr的发射强度,考察铁基体对Ni和Cr的光谱干扰。实验结果表明:铁基体对Ni和Cr均存在光谱干扰,将实验方法用于不锈钢标准样品中Ni和Cr的测定,经光谱干扰校正后,结果与参考值吻合,测定结果的绝对误差在0.35%~0.63%间,相对标准偏差(RSD,n=6)在0.68%~1.1%间。     

电感耦合等离子体发射光谱测定钼铝合金中硅含量的方法研究

采用王水、氢氟酸在180℃加热条件下溶解试样,全面分析了硅元素的212.412、221.667、251.611、252.851、288.158 nm五条分析谱线的受干扰情况,最终选择了灵敏度和信噪比较高、受钼基体干扰程度较小的Si 288.158 nm为分析谱线。使用多谱线拟合(MSF)技术建立了Si 288.158 nm的光谱校正模型,通过校正模型对样品检测信号峰进行了校正,消除了基体钼(Mo 288.137 nm)的光谱干扰,建立了电感耦合等离子体发射光谱法(ICP-OES)测定钼铝合金中硅含量的方法。该方法在0.10～5.00 mg/L范围内(对应固体样品中硅的质量分数范围为0.010%～0.50%),硅的工作曲线线性关系良好,相关系数为0.9995;方法检出限和定量限分别为23μg/g和76μg/g;对3个不同含量的钼铝样品中的硅含量进行了测定,测定结果的相对标准偏差(RSD)在0.76%～1.36%之间,加标回收率在98.0%～106%范围,与标准(YS/T 1075.3-2015)中钼蓝分光光度法的测定结果一致。     

电感耦合等离子体原子发射光谱(ICP-AES)法测定TB9钛合金中微量Si

采用电感耦合等离子体原子发射光谱(ICP-AES)法对TB9钛合金中微量Si的测定进行了研究。总结了基体对较灵敏Si的8条分析线的光谱干扰,发现从Si 185.067nm到Si 288.158nm均有不同基体元素的干扰,对微量Si的测定影响很大。经研究对比,选用背景相对低且信噪比高的Si 288.158nm线,以试剂加定量V为空白来校正基体V的光谱叠加干扰,标准加入法测定。方法检出限0.04μg/mL,标准加入校准曲线的线性相关系数0.999 9。样品加标回收率为100%~105%,相对标准偏差(n=8)小于2.0%。方法简便可靠,可获得满意的分析结果。     

电感耦合等离子体原子发射光谱法测定压水反应堆硼酸介质中的铬、镍、钴

建立电感耦合等离子体原子发射光谱法测定压水反应堆硼酸介质中铬、镍、钴含量的分析方法。分析谱线为Cr 206.158 nm,Ni 221.648 nm,Co 231.160 nm。对样品作酸化处理,使用线性加权校正,采用基本匹配和多谱线拟合技术联用消除光谱干扰。对于硼基体浓度为0～2 500 mg/kg的样品,铬、钴的线性范围为10～200μg/kg,镍的线性范围为40～800μg/kg,线性相关系数均大于0.999,铬、镍、钴的检出限分别为0.81,0.67,0.67μg/kg。测定结果的相对误差不大于7.7%,测定结果的相对标准偏差不大于3.1%(n=6),加标回收率为91.5%～108.5%。该方法检测快速,测定结果准确,光谱干扰校正模型稳定,能满足实际生产需要。     

电感耦合等离子体原子发射光谱法测定钒铝合金中15种杂质元素

提出了电感耦合等离子体原子发射光谱法测定钒铝合金中15种杂质元素硼、钨、硅、铁、铅、锡、砷、镍、铬、钴、铜、磷、锰、镁和钼含量的方法。选择了各元素的分析谱线及背景校正位置避免光谱干扰;采用基体匹配和同步背景校正消除基体影响。方法的检出限（3s）在5.0～100μg·L^-1之间,背景等效浓度在5～95μg·L^-1之间。方法用于钒铝合金样品的分析结果与德国GfE公司测定值一致。方法的回收率在95.3%～110%之间;各元素含量不小于0.010%时的测定值的相对标准偏差（n=8）小于5.0%;各元素含量在0.001%～0.010%时,相对标准偏差小于9.0%。     

电感耦合等离子体原子发射光谱(ICP-AES)法测定高铁土壤中的铝

采用碱熔再酸化分解样品,电感耦合等离子体原子发射光谱(ICP-AES)法测定高铁土壤中的铝(Al)元素。通过逐级扩大线性范围的方式,选取测定高含量Al的合适谱线;在标准中逐级加入铁基体,考察了铁基体浓度从20μg/mL到80μg/mL时对测定Al的各谱线的干扰情况。用ICP-AES法对国家标准物质GSS-1、GSS-2、GSS-3、GSS-4、GSS-5进行测定,测定值与认定值的相对误差(RE)在-0.37%～0.31%,相对标准偏差(RSD,n=5)为0.26%～0.75%,获得了满意结果。     

电感耦合等离子体原子发射光谱（ICP-AES）法测定高铁土壤中Al

采用碱熔再酸化分解样品,电感耦合等离子体原子发射光谱法(ICP—AES)测定高铁土壤中Al。通过逐级扩大线性范围的方式,选取测定高含量Al的合适谱线;在标准中逐级加入铁基体,考察了铁基体浓度从20μg/mL到80μg/mL时对测定Al的各谱线的干扰情况。用ICP—AES对国家标准物质GSS-1,GSS-2,GSS-3,GSS-4,GSS-5进行测定,测定值与认定值的相对误差(RE)在-0.37 %～0.31%之间,RSD(n= 5)为0.26％～0.75％ 。     

电感耦合等离子体原子发射光谱(ICP-AES)法测定高铁土壤中的铝

采用碱熔再酸化分解样品,电感耦合等离子体原子发射光谱(ICP-AES)法测定高铁土壤中的铝(Al)元素。通过逐级扩大线性范围的方式,选取测定高含量Al的合适谱线;在标准中逐级加入铁基体,考察了铁基体浓度从20μg/mL到80μg/mL时对测定Al的各谱线的干扰情况。用ICP-AES法对国家标准物质GSS-1、GSS-2、GSS-3、GSS-4、GSS-5进行测定,测定值与认定值的相对误差(RE)在-0.37%～0.31%,相对标准偏差(RSD,n=5)为0.26%～0.75%,获得了满意结果。     

X射线荧光光谱法测定高铬型钒渣中主次组分

称取于750~800℃灼烧2h后的试样0.300 0g,置于盛有4.000 0g四硼酸锂、3.000 0g偏硼酸锂、0.500 0g碳酸锂的铂黄坩埚中,搅匀,加入300g·L-1溴化锂溶液0.5mL,在(1 050±20)℃熔融制片,采用X射线荧光光谱法测定高铬型钒渣中主次组分含量。采用钒渣标准样品和由标准样品加基准物质配制成的系列校准样品绘制校准曲线以消除基体效应,选择分析谱线并进行谱线重叠干扰校正。各组分的质量分数在一定范围内与荧光强度呈线性关系。方法用于分析高铬型钒渣样品,所得结果与滴定法、电感耦合等离子体原子发射光谱法的结果一致,测定值的相对标准偏差(n=10)在0.030%~7.3%之间。     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

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.