比浊法测定氯化石蜡中氯量

以Na2CO3-MgO-KOH为灰化固定剂,用灰化法处理氯化石蜡样品。对测定条件、灰化条件及AgCl胶体的稳定性进行了考察。建立了比浊法测定氯化石蜡中氯的新方法。线性范围为0~5μg/mL。测定结果的相对标准偏差≤0.6%,加标回收率为97.5%~102.3%。     

超临界二氧化碳流体萃取法测定玩具中15种致敏芳香化合物

该文以欧盟新玩具指令中限用或禁用的15种致敏芳香化合物为研究目标,研究了超临界二氧化碳萃取压力、温度、夹带剂等条件对萃取效率的影响,建立了超临界流体萃取/气相色谱-质谱联用仪测定玩具中15种致敏芳香化合物的分析方法。最佳萃取条件为:萃取温度50℃,压力300 bar,二氧化碳流速30g/min,夹带剂甲醇含量3%,动态萃取30 min,静态萃取30 min。萃取物经DB-17MS色谱柱分离后,采用质谱仪进行检测,内标法定量。15种化合物在0.02~60μg/mL范围呈良好线性,相关系数为0.993 2~0.999 9,检出限(S/N=10)为0.02~0.09μg/mL。该法检测聚丙烯(PP)、聚乙烯(PE)、丙烯腈-丁二烯-苯乙烯(ABS)塑料的回收率分别为79.6%~114.5%、75.0%~118.9%、72.7%~114.9%,相对标准偏差为3.2%~11.0%、0.6%~11.6%、3.5%~11.0%。建立的方法灵敏、环保,可用于玩具中致敏芳香化合物的检测。     

超临界二氧化碳流体萃取法测定玩具中15种致敏芳香化合物

该文以欧盟新玩具指令中限用或禁用的15种致敏芳香化合物为研究目标,研究了超临界二氧化碳萃取压力、温度、夹带剂等条件对萃取效率的影响,建立了超临界流体萃取/气相色谱-质谱联用仪测定玩具中15种致敏芳香化合物的分析方法。最佳萃取条件为：萃取温度50 ℃,压力300 bar,二氧化碳流速30 g/min,夹带剂甲醇含量3%,动态萃取30 min,静态萃取30 min。萃取物经DB-17MS色谱柱分离后,采用质谱仪进行检测,内标法定量。15种化合物在0.02~60 μg/mL范围呈良好线性,相关系数为0.993 2~0.999 9,检出限(S/N=10) 为0.02~0.09 μg/mL。该法检测聚丙烯(PP)、聚乙烯(PE)、丙烯腈-丁二烯-苯乙烯(ABS)塑料的回收率分别为79.6%~114.5%、75.0%~118.9%、72.7%~114.9%,相对标准偏差为3.2%~11.0%、0.6%~11.6%、3.5%~11.0%。建立的方法灵敏、环保,可用于玩具中致敏芳香化合物的检测。     

单滴微萃取-气相色谱质谱联用法测定纺织品中可分解芳香胺

建立了单滴微萃取结合气相色谱-质谱法测定纺织品中可分解芳香胺的方法。研究了萃取剂种类、萃取剂体积、萃取时间、pH和搅拌速度等条件对单滴微萃取效率的影响。确定最佳萃取条件:在室温条件下,取5 mL样液,调节被萃取液pH8,以2μL氯苯为萃取剂萃取20 min,搅拌速度为200 r/min。在优化的实验条件下,检出限为0.08~0.14 mg/kg,线性范围0.5~50 mg/kg,线性相关系数大于0.996,平均加标回收率为75.3%~96.7%,相对标准偏差为3.6%~8.7%。方法适合纺织品中可分解芳香胺的测定。     

采用钯基体改进剂石墨炉原子吸收法测定纺织品中的可萃取铅

纺织品标准中对铅的限量极为严格,但萃取汗液基体成分复杂,背景吸收干扰强烈,为解决纺织品中的可萃取铅检测的困难,建立了一种采用基体改进剂的石墨炉原子吸收光谱法,测定纺织品中的可萃取铅。通过比较两种基体改进剂,优化实验条件,确定了以钯-硝酸镁为基体改进剂、灰化温度1 200℃、原子化温度2 300℃的实验条件。结果表明,以钯-硝酸镁为基体改进剂更能有效降低纺织品可萃取铅的基体干扰,并且具有良好的精密度(2.6%~3.3%)和准确度(加标回收率94.3%~105.6%)。     

缓释尿素中硝化抑制剂DMPP的气相色谱法测定

建立了一种检测缓释尿素中吡唑类硝化抑制剂DMPP的气相色谱法。DMPP在尿素水溶液中可定量转化为DMP,从5种有机溶剂中选择氯仿作为DMP的萃取剂,并采用加入KCl盐析的方法将萃取率从96.1%提高到99.5%。本文采用吡啶作为内标物,通过DB-1701气相色谱柱,氢火焰离子化检测器(FID)定量检测氯仿溶液萃取相中的DMP。萃取率为98.8%~100.4%;添加回收率为98.1%~99.5%;RSD为0.84%~1.6%。应用本法测定自制缓释尿素中DMPP质量分数为0.44%。     

加速溶剂萃取-在线净化-气相色谱-质谱法测定土壤中多氯烃类化合物

以土壤中六氯环戊二烯、六氯丁二烯、六氯乙烷为研究对象,采用加速溶剂萃取法进行在线净化和萃取,用气相色谱-质谱法测定。将土壤样品10g与石英砂20g混合均匀后,加入到装有氟罗里硅土粉1g和石墨炭黑粉0.2g的萃取池中,以二氯甲烷-丙酮(4+1)混合液为萃取剂进行萃取。考察了萃取温度、萃取剂、分散剂和土壤pH、TOC等因素的影响,分析了在线净化和离线净化的差异以及复合净化的优势。应用该方法对3个不同土壤样品进行测定,回收率在72.3%~89.0%之间,相对标准偏差(n=7)为7.4%~13%。     

中空纤维顶空液相微萃取-气相色谱法测定胶黏剂中正己烷

建立了以中空纤维顶空液相微萃取(HF-HS-LPME)为样品前处理技术,结合气相色谱法测定胶黏剂中正己烷含量的方法。通过对萃取剂的选择、温度、时间、搅拌速率、盐效应等参数的优化,确定了最佳实验条件:以邻二甲苯作为有机萃取剂,萃取温度为80℃,萃取时间为45 min,搅拌速率为700 r/min,Na Cl加入量为4 mol/L。萃取后,取0.5μL接收相进行气相色谱分析。正己烷含量的标准曲线在0.0138~1.38 g/L范围内线性关系良好,相关系数为0.9995,相对标准偏差(RSD)为2.6%,方法的检出限(LOD)为89.2μg/L(经LPM E后LOD则可达5.2μg/L)。研究还发现,正己烷初始质量浓度在3.46~138 mg/L范围内时,富集倍数随正己烷初始浓度的增大呈对数型降低,这为LPM E的理论研究提供了新的论据。方法应用于胶黏剂样品分析,平均加标回收率为92.3%~96.2%,RSD为3.6%~4.7%。     

分散液相微萃取技术与GC/MS联用检测生物样品中拟除虫菊酯类杀虫剂

建立了分散液相微萃取与GC/MS联用分析人体尿液中拟除虫菊酯类杀虫剂的方法。确定了分散液相微萃取最优萃取条件:30 mg薄荷醇作为萃取剂,0.5 m L甲醇作为分散剂,萃取时间为2 min,离心时间为5 min,在此条件下进行分析,三氟氯氰菊酯、氯菊酯、氰戊菊酯的检出限分别为3.3,3.3和10 ng/m L,相对标准偏差分别为1.8%~12%,3.3%~5.7%,3.8%~13%,富集倍数分别为460,512,1302。     

蔬菜中甲胺磷等5种有机磷农药残留量的分散液-液微萃取/气质联用技术检测

建立了分散液-液微萃取/气相色谱质谱(DLLME/GC-MS)联用技术分析蔬菜样品中甲胺磷、甲拌磷、甲基对硫磷、毒死蜱和乐果5种有机磷农药残留的新方法。优化后的萃取条件:10μL氯苯为萃取剂,1.0 mL丙酮为分散剂,萃取时间为3 m in。5种有机磷农药均具有良好的线性关系,相关系数不低于0.995,加标回收率为60%~95%,相对标准偏差为2.8%~9.1%,检出限为0.001~0.140 mg/kg。应用于蔬菜中有机磷农药残留的检测,结果满意。     

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.