微波消解分光光度法测定污水中的总磷

建立微波消解分光光度法测定污水中总磷的方法。采用微波消解法消解污水．讨论了消解时间和压力对消解效果的影响。测定总磷的线性范围为0～0．4mg/L。用该法测定总磷环境标准样品中的总磷,测定结果与标准值基本一致,测定结果的相对标准偏差为1．65％(n=5)。     

微波消解-分光光度法测定石油焦中的钒

研究了用微波消解分光光度法测定石油焦中的钒。在石油焦样品处理中采用了常规溶样及微波消解两种方法。重点研究了微波消解石油焦样品的方法,详细考察了微波消解时样品的最佳用量、消解压力、功率、时间,建立了最佳微波消解程序。结果表明两种方法测定结果基本吻合。样品测定的RSD小于4、02％,加标回收率均在98．6％～102．7％之间,但微波消解法的溶样速度是常规法的10倍。钒的线性范围为0～8．0g／L。结果表明,微波消解分光光度法测定石油焦中的钒是一种快速、准确且无环境污染的方法。     

微波消解-氢化物发生原子荧光法测定塑料原料及其制品中的砷、汞

采用微波消解进行样品前处理，以硫脲为预还原剂，用氢化物发生原子荧光法测定塑料原料及其制品中的砷、汞。测定砷和汞的线性范围均为0～8μg／L，砷、汞的检出限分别为0．005、0．076μg／L，测定结果的相对标准偏差分别为4.96％～7．38％、2．94％～7．20％(n=6)，回收率分别为92．0％～103．2％、92．0％～98.0％。     

微波消解-氢化物发生原子荧光光谱法测定头发样品中的微量汞

对微波消解-氢化物发生原子荧光光谱法测定头发样品中微量汞的方法进行了研究。采用HNO3和H2O2作消解剂,在最佳微波消解条件和测定条件下,线性回归线方程为Y=259．7c 155.4,相关系数r=0.9996,检出限为0．01ng／mL,线性范围为0-20ng／mL。测定结果的相对标准偏差为0,4％～2．8％,回收率为94,0％-102．0％。     

微波消解-微波等离子体炬原子发射光谱法测定原油和渣油中的铁、镍、铜和钠

采用微波消解技术消解原油和渣油,利用微波等离子体炬原子发射光谱法测定原油和渣油中的Fe、Ni、Cu、Na。考察了原油和渣油的最佳消解条件、各元素测定条件及共存元素对测定的影响。方法对Fe、Ni、Cu和Na元素的检出限分别为22、42、2．0和1．0μg/L;线性范围分别为0．1-100、0．15-50、0．01-5．0和0．006-2．0mg／L,应用该方法测定实际样品中Fe、Ni、Cu和Na的相对标准偏差分别为3．9％、3．6％、5．5％和3．4％。微波消解样品的测定结果与常规干法灰化法的测定结果相吻合。本方法省时、省酸、简便、快速,没有环境污染,具有一定的实际应用价值。     

微波消解-紫外分光光度法测定水中总氮

研究了用微波消解-紫外分光光度法测定水样中的总氮,结果表明,所提出的消解方法具有操作简单、省时、消解完全的特点,精密度和准确度均令人满意．方法的线性范吲为0．0242～9．60mg／L,水样加标回收率为101％～103％,相对标准偏差为0．13％～0．44％。     

微波消解-微波等离子体炬原子发射光谱法测定汽油中痕量铜和铁

采用微波消解方法处理汽油样品,用微波等离子体炬原子发射光谱法（MPT—AES）测定消解液中的铜和铁含量。考察了微波功率、载气流量、工作气流量、酸效应、共存离子等实验参数对测定铜和铁的影响,并进行了系统优化,测得铜和铁的检出限分别为2．1ng／mL和22．1ng／ml。线性范围分别为0．01～12μg/mL和0．1～100μg／mL。详细考察了微波消解酸种类及用量,消解温度、运行时间及微波功率等对微波消解的影响。结果表明,各元素测定结果的RSD均小于3．5％,铜的回收率为93％-107％,铁的回收率为92％-106％。与传统的碘-二甲苯-硝酸反萃取处理法相比,此法具有元素损失少,操作简单,无需使用有毒氧化剂,减少污染,改善工作环境等优点,是行之有效的汽油样品预处理方法。     

火焰原子吸收光谱法测定尘铅前处理方法的研究

采用火焰原子吸收光谱法测定尘铅样品,在0-1．00mg／L范围内样品中铅含量与吸光度呈良好线性关系,检出限为2．88μg／m^2（按定容体积50mL、采样体积400L计）。采取酸煮法、索氏提取法、微波消解法、超声波提取法等4种前处理方法,在0．100,0．500,1．00mg3个质量水平对空白滤筒进行加标回收试验,4种前处理方法的回收率和测定结果的相对标准偏差分别为91．8％-97．4％,2．2％～3．2％;83．0％-86．8％,7．4％-10．3％;93．6％-97．2％,2．5％～3．7％;89．3％-90．9％,3．2％～4．5％,提取效果以酸煮法和微波消解法最佳,超声波提取法次之,索氏提取法最差。     

溴代靛红异构体含量的同时测定

采用紫外二阶导数分光光度法测定常山酮合成工艺中同分异构体6-溴靛红和4-溴靛红的含量。4-溴靛红测定的线性范围2～80mg/L,相对标准偏差0．178％,回收率99．9％～100．1％;6-溴靛红测定的线性范围2～60mg/L,相对标准偏差0．091％,回收率98．7％～100.1％。该法简便、快捷、准确、灵敏。     

通讯作者：于冀芳,石家庄市鹿泉区上庄大街河北省质检中心,050000, 18032188277,

采用微波消解技术对工业锅炉用水进行前处理,建立了微波消解-电感耦合等离子体发射光谱法(ICP-AES)测定工业锅炉用水中钙、镁、铁、铜含量的分析方法。分别对样品的微波消解温度和保持时间进行讨论,优化了微波消解前处理技术。结果表明：给水在消解温度为170 ℃,保持时间为10 min条件下,回水在消解温度为180 ℃,保持时间为12 min条件下,锅炉水在消解温度为185 ℃,保持时间为15 min条件下,微波消解最理想。应用本方法对锅炉用水中钙、镁、铁、铜进行测定,线性范围均为0～2.0 mg/L,检出限分别为0.002 mg/L、0.002 mg/L、0.003 mg/L、0.004 mg/L,回收率为95%～103%,相对标准偏差RSD(n=7)均小于9.32%,与原子吸收法(AAS)进行比较,测定结果基本一致。     

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.     

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.     

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.     

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.