铬铁矿中铁的快速测定方法研究

研究了铬铁矿中铁的测定方法问题。基于测定铬铁矿中铬的溶样方法原理和对传统无汞测铁程序的改进研究,推荐了一个测定铬铁矿中铁的快速方法模式:试样经沸腾硫酸湿烧(～330℃)、磷-硫混合酸溶解、直接用三氯化钛溶液还原铁(Ⅲ→Ⅱ)、过量钛(Ⅲ)自然被氧化后,用常规法滴定之。所提供的快速方法测得之结果准确可靠(RSD=0.55%～0.80%,n=8),适于普遍推广应用。     

沉淀分离-密闭消解-电感耦合等离子体质谱法测定铬铁矿中铂族元素

建立了沉淀分离-密闭消解-电感耦合等离子体质谱法测定铬铁矿中铂族元素的新方法。采用硫磷混酸溶样(1:2,V/V),以硫酸肼为还原剂,实现了硫脲对包括Os在内的全部铂族元素的沉淀富集,沉淀经密闭溶样技术快速消解后接ICP-MS测定。试验中筛选出HBr来消除Os的记忆效应,并考察了Os在王水介质中的稳定性。结果表明:铂族6个元素的线性相关系数均在0.999以上,对标准物质GBW07292平行测定6次的相对标准偏差(RSD,n=6)在2.7%～8.4%之间,方法检出限(3σ)在0.055～0.21ng/g,采用国家一级标准物质GBW07201,GBW07202,GBW07292进行方法验证,测定值与认定值基本一致。     

重铬酸钾滴定法测定废杂铜中的铁含量

研究了废杂铜中铁含量的测定方法。试料采用盐酸、硝酸、高氯酸溶解,加入过量氨水生成氢氧化铁沉淀与铜、铬等干扰元素分离,沉淀用热盐酸溶解后,用氯化亚锡还原至溶液呈浅黄色,重铬酸钾滴定法测定铁含量。探讨了溶样方式、氯化铵用量、氨水过量的体积、硫磷混酸用量对测定结果的影响。对4个废杂铜样品中的铁含量进行测定,测定结果的相对标准偏差RSD(n=11)为0.38%～0.95%,加标回收率为99.4%～100%,方法准确可靠,能够满足测定要求。     

微波消解-电感耦合等离子体原子发射光谱(ICP-AES)法测定含铜污泥中多种重金属

为了填补现有方法的技术空白,本方法采用微波消解和电感耦合等离子体原子发射光谱法（ ICP-AES）相结合,实现对含铜污泥中铅、锌、铬、镉、砷、镁、铝、锑量的同时测定。首先采用盐酸-硝酸-氢氟酸微波消解进行样品的前处理,消解后加入高氯酸置于电热板进行除碳并赶酸,溶样效果理想,且有效避免了高温溶样对易挥发元素砷、锑的损失,整个过程安全、高效、无损。溶样后以电感耦合等离子体发射光谱法（ ICP-AES）进行测定。对含铜污泥的分解方法进行了合理选择,并对测定时的元素分析谱线及各测定元素间干扰情况等进行了讨论。该方法的加标回收率在95.31%~107.28%%,相对标准偏差（RSD）在0.31%~2.05%之间（n=7),结果表明,该方法准确度高,操作简单快捷,可同时测定多种元素,能满足批量的测定含铜污泥中铅、锌、镍、铁、镉、铬、砷、锑含量的测定要求。     

微波消解ICP-AES法测定高速工具钢中锰、磷、镍、铜、铬、钒

高速工具钢为高碳高合金工具钢,常温下样品酸溶分解较为困难。本文利用微波消解提高溶样的温度和压力,在王水、氢氟酸和硫酸介质中使样品充分消解,再用饱和硼酸溶液络合过量的氢氟酸,基体匹配消除铁基体的影响,ICP-AES法同时测定锰、磷、镍、铜、铬、钒的含量。测定高速工具钢标样,测定值与标样值相吻合,本方法的精密度在0.55%～4.06%。加标回收率在95.6%～114.8%,满足测定要求。     

快速氧化还原滴定法测定铬铜中间合金中铬

铬铜中间合金中铬的化学法测定，国内多数采用铬青铜中铬的测定法^[1,2]，即硝酸溶样，浓硫酸，浓磷酸介质中冒硫酸烟的高温下进一步溶解铬，然后在酸性介质中用过硫酸铵氧化Cr^3 为Cr2O7^2-，再用硫酸亚铁铵滴定求得铬含量，该方法的主要缺点是需在硫酸微微冒烟下长达30min，左右才可把铬溶解，分解试样时大量二氧化硫排入空气中，对周围环境造成严重污染，另外溶样以后还得进一步氧化Cr3 为CrO7^2-才可测定，因而消耗时间较长。     

电感耦合等离子体原子发射光谱法测定新型富钛料中的杂质元素

采用电感耦合等离子体原子发射光谱法测定新型富钛料中杂质元素锰、磷、钒、铁、钙、镁、铬和铝的含量。样品用硝酸、盐酸、氢氟酸和硫酸（1+1）溶液消解。对共存元素进行了干扰试验,采用基体匹配和同步背景校正措施消除基体影响。方法的检出限（3s）在0.000 9～0.085 mg·L^-1之间。应用此法分析了新型富钛料试样,测定结果与其它化学分析方法测定值一致。方法的回收率在95.8%～113%之间;相对标准偏差（n=11）小于3.9%。     

沉淀分离-密闭消解-电感耦合等离子体质谱法测定铬铁矿中铂族元素EI北大核心CSCD

建立了沉淀分离-密闭消解-电感耦合等离子体质谱法测定铬铁矿中铂族元素的新方法。采用硫磷混酸溶样(1:2,V/V),以硫酸肼为还原剂,实现了硫脲对包括Os在内的全部铂族元素的沉淀富集,沉淀经密闭溶样技术快速消解后接ICP-MS测定。试验中筛选出HBr来消除Os的记忆效应,并考察了Os在王水介质中的稳定性。结果表明:铂族6个元素的线性相关系数均在0.999以上,对标准物质GBW07292平行测定6次的相对标准偏差(RSD,n=6)在2.7%~8.4%之间,方法检出限(3σ)在0.055~0.21ng/g,采用国家一级标准物质GBW07201,GBW07202,GBW07292进行方法验证,测定值与认定值基本一致。     

四酸溶矿-电感耦合等离子体发射光谱法测定铬铁矿中多种元素

建立了四酸溶矿-电感耦合等离子体发射光谱法同时测定铬铁矿中铝、钙、镁、铁、钛、锰、钾、钠、钒、钴、镍的方法。本法在四酸溶矿基础上,用HClHCl O4除铬,使铬以氯化铬酰形式挥发除去,消除了铬在测定时对其它元素的干扰,同时弥补了碱熔时无法测定钾、钠的弊端。对试样的分解、铬干扰的消除、溶液中残存铬的影响及仪器参数进行了探讨研究。本法空白值低,检出限为1~48μg/g,方法 RSD(n=12)为0.93%~9.2%,相对误差为-8.2%~3.6%。通过一系列铬铁矿标准物质及实测样品进行方法验证,四酸溶矿测定值与碱熔的ICP-AES的测定值进行比对,结果均在误差范围内,满足地质矿产检测的要求。该法分析过程简单,避免了在溶矿过程中引入其它待测元素,因消除了铬的干扰,一套标准系列即可满足测试要求,实用性强,适合铬铁矿中钾、钠等元素的测定。     

快速加热容量法测定土壤中有机质含量

建立快速容量法测定土壤中有机质的分析方法。采用恒温电热板控温加热替代油浴加热溶解样品,使用硫酸银作为催化剂,重铬酸钾–硫酸标准溶液作为氧化剂,使用硫酸亚铁铵溶液为滴定剂,测定土壤中有机质含量。优化后的分析条件:溶样温度为220℃,溶样时间为(5.5±0.5) min,催化剂用量为0.08 g。对3个国家一级标准物质进行分析,测定结果与推荐值相符,相对误差为–4.0%～0.0%,相对标准偏差为1.17%～3.66%(n=6)。该法可用于大批量土壤样品中有机碳含量的快速测定。     

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.     

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.     

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.     

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.