高纯金中杂质元素的电感耦合高频等离子体原子发射光谱法测定

研究了萃取金后用ＩＣＰ－ＡＥＳ法测定微量Ｐｔ、Ｐｄ、Ｒｈ、Ｉｒ、Ａｇ等２８个杂质元素的方法。元素间的干扰用等效浓度法校正。杂质元素标准加入回收率为７５％～１１８％；相对标准偏差为４．３％～２０％；取样量为２．５ｇ时，测定下限为５×１０＾５％～２×１０＾－４％。     

压力溶弹溶样石墨炉原子吸收法测定硫磺中的砷、硒、碲

建立了硝酸压力溶弹溶样、石墨炉原子吸收法测定硫磺中砷、硒、碲元素的方法。通过正交试验确定样品的溶解条件，选择适当的基体改进剂和最佳的石墨炉升温程序，一次溶样即可实现砷、硒、碲三种元素的检测。该法的回收率为90．0％～110．0％，测定结果的相对标准偏差为2．5％～4．8％。     

絮凝剂中铝、砷、镉、汞、锰和铅的测定

1 引 言聚合硫酸铝是一种新型絮凝剂，可以用作污水处理。一般固铝含量为１０％～３０％，Ａｓ、Ｃｄ、Ｈｇ、Ｍｎ、Ｐｂ的含量为ｎｇ～ｍｇ／Ｌ级。通常测定这些元素的方法为分光光度法、原子吸收法、滴定法、原子荧光法等。这些方法对于聚合硫酸铝来讲，有的达不到测定灵敏度，有的基体干扰严重，有的前处理繁琐、费力，有的测定费时，并且大多数方法不能同时测定多元素。以等离子体质谱法测定絮凝剂聚合硫酸铝中的６种有毒元素Ａｌ、Ａｓ、Ｃｄ、Ｈｇ、Ｍｎ、Ｐｈ含量，测定准确度分别为9７．０％、１０４％、８８．４％、９２．８％、９…     

HPLC法测定纺织品中八种致敏禁用分散染料

建立了HPLC法测定纺织品中8种致敏禁用分散染料的方法。流动相为甲醇-四氢呋喃-乙酸铵水溶液,检测波长为595nm和440nm,8种成分在1～50mg／L范围内与峰面积呈良好的线性关系,r值大于0.997;保留时间的RSD值在0．14％～0．24％之间;峰面积的RSD值在1．54％～3．69％之间;检出限在0．1～1mg.L之间．结果表明该法简便,结果可靠,已用于纺织品出口的检验中。     

ICP-AES法测定枸橼酸铋制剂中的杂质元素

采用微波消解的方法溶样,用ICP-AES法同时测定了枸橼酸铋制剂中的Ca、Mg、Cr、Mn等杂质元素的含量,考察了微波消解的条件和基体元素Bi对被测元素分析谱线强度的影响。方法的检出限为0．6～16ng／mL,相对标准偏差为1．58％～6．64％,加标回收率为92％～104％。该方法简单、快速、准确,结果令人满意。     

ICP-AES法同时测定配合饲料中的微量元素

采用ICP—AES法同时测定配合饲料中Cu、Fe、Mn、Zn、Ca、Mg、P、Pb、Cr、Cd元素的含量。选择了合适的分析线、溶样酸及酸的用量，各元素测定结果的相对标准偏差为0．40％～6．52％，回收率为90．8％～104．5％。     

端视ICP-AES法测定茶叶中铅铜砷镉铬钴

研究了用ICP-AES法同时测定茶叶中6种重金属元素铅、铜、砷(为类金属元素)、镉、铬、钴的分析方法。方法回收率都在90％～104％之间，相对标准偏差在0．1％～8．3％之间，对茶叶标准物的测定值与推荐值基本一致，方法简便、准确，结栗满意。     

高纯钨酸钠中痕量杂质元素的共沉淀分离和ICP—AES测定

提出了以氢氧化镧为共沉淀剂，对高纯钨酸钠中痕量金属杂质元素（钙，镉，钴，铜，铁，锰，镍，锌）进行了共沉淀分离富集后以ＩＣＰ－ＡＥＳ法进行测定的方法，ｐＨ１２时，用１０ｇ．Ｌ＾－１镧溶液６ｍｌ进行两次共沉淀，能使杂质元素定量分离回收，钨酸钠残留量降至很低水平，试样测定结果表明，各元素回收率在９２．４％～１０４．８％之间，相对标准偏差为１．８％～６．９％。     

ICP—AES法测定饲料中钙、磷含量

采用干灰化法处理饲料样品,以全谱直读ICP—AES法对饲料中钙、磷元素进行了测定。结果表明,该法测定钙的相对标准偏差为0．18％～0．76％,测定磷的相对标准偏差为0．37％～1．02％;钙元素的加标回收率为99．6％-100．3％,磷元素的加标回收率为97．8％-100．5％;该法与国家标准比对,结果准确可靠。     

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。     

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.     

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.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.