热脱附/冷阱捕集–气相色谱法同时测定空气中多种挥发性有机物

使用Tanax-TA管富集样品,建立热脱附/冷阱捕集–气相色谱法同时测定工作场所空气中苯系物、丙酮、丁酮、乙酸乙酯、乙酸丁酯等12种常见挥发性有机物分析方法。该法线性范围为5~100μg/m L,相关系数不小于0.999 0。12种挥发性有机物的检出限为3.0×10~(–4)~1.7×10~(–3) mg/m~3(以采样体积为1 L计),加标回收率为80.9%~106.5%,测定结果的相对标准偏差为2.08%~4.09%(n=10)。该法样品处理简单,可应用于工作场所空气中挥发性有机物的快速测定。     

气相色谱-质谱法检测人造板中挥发性有机物

取过0.18 mm筛的人造板粉末0.300 0 g,在60℃水浴中进行顶空固相微萃取(SPME)30 min;用75μm CAR/PDMS纤维头富集样品释放出的挥发性有机物。使用自制简易冷阱聚焦装置,将纤维头插入气相色谱(GC)进样口解吸3 min,所得溶液采用气相色谱-质谱法检测其中的挥发性有机物。结果表明:在刨花板、中密度纤维板及胶合板中,共检出95种物质,其中苯系物27种,醛/酮类11种,烷烃类8种,醇/酯类11种,萜类物质38种。     

农产品中6种有机溶剂残留的气相色谱-质谱检测方法

建立了蔬菜、粮食等农产品中6种有机溶剂残留(甲苯、邻二甲苯、间二甲苯、对二甲苯、N,N-二甲基甲酰胺(DMF)和二甲基亚砜(DMSO)的液液萃取/气相色谱-质谱分析方法。不同类型的样品经乙腈-水溶液或乙腈溶剂提取后,用Agilent DB-624(30.0 m×250μm×1.4μm)毛细管色谱柱分离,在GC-MS选择离子监测(SIM)模式下检测,以保留时间和特征离子丰度比定性,外标法定量。结果表明,该方法对不同样品中4种苯系物在0.005~0.500 mg/L,DMF在0.025~0.125 mg/L,DMSO在0.050~0.500 mg/L浓度范围内线性关系良好,相关系数(r)为0.992 0~0.997 1。6种有机溶剂的平均加标回收率为60.1%~115.2%,相对标准偏差不大于11.0%。苯系物、DMF和DMSO的方法检出限(S/N=3)分别为0.002~0.050,0.010~0.025,0.060~0.150 mg/kg。该方法准确、快速、灵敏,可用于各种农产品中有机溶剂残留的监控。     

地下水检测典型挥发性有机物标准样品研究

依据我国地下水污染现状,研究制备了地下水中典型挥发性有机物(VOCs)质量控制模拟标准样品,包含4种卤代烃和6种苯系物,经过气相色谱/质谱分析检测,均匀性和稳定性良好。组织行业内9家实验室,探索开展水中挥发性有机物检测的协作定值研究。开展不确定度来源分析和量值评定,标准样品的标准值和扩展不确定度(k=2)为:三氯甲烷(60.6±5.4)μg/L、四氯化碳(60.2±7.4)μg/L、三氯乙烯(60.4±5.8)μg/L、四氯乙烯(60.6±7.6)μg/L、苯(60.9±4.2)μg/L、甲苯(60.4±4.8)μg/L、乙苯(60.7±5.0)μg/L、邻二甲苯(60.5±6.2)μg/L、间二甲苯(60.4±6.2)μg/L、对二甲苯(60.4±6.2)μg/L。本标准样品主要用于地下水、地表水和饮用水环境监测工作中质量控制、分析方法验证、仪器性能的核查以及技术人员能力考核等。     

神木半焦粉末萃取物的组成特征（英文）

依次用石油醚、CS2、CH2Cl2、丙酮和甲醇在索氏萃取器中萃取了神木半焦粉末,得到了五级萃取物(E1-5)和最终的萃余物,总萃取率为1.76%。分别用气相色谱/质谱联用仪(GC/MS)、大气压固体探针/飞行时间质谱仪(ASAP/TOF-MS)和电喷雾电离/飞行时间质谱仪(ESI/TOF-MS)分析了各级萃取物。用GC/MS分析的结果表明,在E1中C15-24的直链烷烃和E2中3与4环的芳烃比较丰富,在E3-5中含杂原子有机化合物较丰富,特别是E4和E5中含氧有机化合物的含量最高。与用GC/M S分析的结果相比,用ASAP/TOF-M S和ESI/TOF-M S从E3-5中检测出更多的含杂原子有机化合物。     

热脱附-单体稳定同位素技术测定挥发性有机物

采用热脱附与稳定同位素质谱联用技术分析了城市不同源及大气环境中挥发性有机物排放的单体同位素特征。系统考察了样品进样量、进样方式和样品分离度对同位素分馏影响情况。使用填有Tenax TA的吸附管采集汽油车尾气、汽油挥发、柴油车尾气、柴油挥发、溶剂挥发和餐饮油烟等污染源,以及城市不同功能区的挥发性有机物(VOCs)样品,不同污染源中挥发性有机物的稳定碳同位素δ13C值不同,97#汽油车尾气的δ13 C值偏重,平均值为-25.84‰,富集13 C;餐饮油烟的δ13 C值偏轻,平均值为-30.26‰。油品挥发比燃烧后以尾气的形式排放的苯系物δ13 C值重。厦门市各功能区挥发性有机物的δ13 C平均范围在-27.03‰~-25.40‰,接近于汽油和柴油挥发及尾气中的δ13 C值,表明厦门市空气中挥发性有机物以机动车排放源为主。     

固相萃取净化-气相色谱-质谱法测定记号笔油墨中8种挥发性苯系物的含量

称取记号笔笔芯中油墨0.200 0g,加入乙酸乙酯至体积为5.0mL,涡旋提取2min,将提取液流经HLB固相萃取柱进行净化处理。经净化的流出液用乙酸乙酯定容至10.0 mL,经0.22μm滤膜过滤,取滤液按仪器工作条件进行气相色谱-质谱法分析。选择HP-INNOWax毛细管色谱柱,在35～220℃之间按程序升温模式对8种挥发性苯系物(苯、甲苯、乙苯、对二甲苯、间二甲苯、异丙苯、邻二甲苯和苯乙烯)进行分离,并在电子轰击离子源(EI)和选择离子监测(SIM)模式下进行质谱测定。8种挥发性苯系物均在0.1～5.0mg·L~(-1)内与其相应的峰面积呈线性关系,其检出限(3S/N)为0.06～0.18mg·kg~(-1)。在阴性样品的基础上,在3个浓度水平上进行加标回收试验,测得8种化合物的回收率为79.8%～114%,测定值的相对标准偏差(n=5)为0.20～11%。应用此方法分析了116支记号笔中不同颜色的油墨样品,苯系物的检出率为76.9%,其质量分数为0.33～3.49×10~4 mg·kg~(-1)。     

汽车内部装饰材料挥发性苯系物的热脱附/气相色谱-质谱法测定

建立了热脱附/气相色谱-质谱测定汽车内部装饰材料中苯、甲苯、邻二甲苯、间二甲苯、对二甲苯、乙苯、苯乙烯等挥发性苯系物的方法.将样品密封于采样袋中,充入5 L纯氮气,置于80 ℃恒温烘箱中加热2 h后,用采样泵抽取1 L气体经过Tenax-TA吸附管,通过热脱附/气相色谱-质谱联用仪对吸附管中苯系物的种类及含量进行测试.研究了样品处理的温度、时间对测试结果的影响.方法检出限0.9 ～1.2 ng/L,测量线性范围0.01 ～3.00 μg,回收率52% ～74%,相对标准偏差4% ～5%.     

固相微萃取联用气相色谱-质谱法快速分析水中痕量苯系物

样品前处理是分析检测的关键步骤,传统的样品前处理技术耗时、费力,且易对环境造成二次污染。固相微萃取（Solid phase microextraction, SPME）技术集采样、萃取、浓缩、进样于一体,萃取过程无需有机溶剂,是一种简单、快速、绿色环保的样品前处理技术。本项目采用SPME技术对水中苯系物进行萃取,优化SPME条件,并联用气相色谱-质谱（Gas chromatography-mass spectrometry,GC-MS）分析检测,建立水中苯系物的定量分析方法。实验结果表明,该方法对苯系物包括苯、甲苯、乙苯、二甲苯的检测具备良好的线性范围(均为100–10000 ng·L^-1),且相关系数R²均大于0.9900。此外,该方法的检测限分别低至37.50、16.67、45.45、10.64 ng·L^-1。将建立的方法用于实际水样中苯系物的检测,加标回收率在86.83%–114.8%之间,方法简便、高效,结果令人满意。本实验将先进的SPME技术引入本科教学实验,一方面融入思政元素,帮助学生牢固树立绿色环保理念,另...     

卤代硅烷(R3SiX)与NR'3形成五配位硅化合物的加成反应

对R3SiX(R=H、CH3;X=F、Cl、Br、I)与NR'3(R'=H、CH3)的加成物用量子化学密度泛函方法在B3LYP/6-31g(d,p)基组下(X原子采用cep-121g基组)进行了两种加成方式的研究.一种是NR'3沿Si-X键轴向位置的加成,另一种是NR'3沿Si-X键侧向接近的加成.计算结果表明,前者更稳定且更容易形成加成物;Si上斥电子基团不利于Si-N键的形成,而N上斥电子基团则有利于Si-N键的形成;NH3-H3SiX系列和N(CH3)H3-H3SiX系列均能以两种方式进行加成,NH3-H2(CH3)SiX系列仅能沿Si-X键轴向进行加成,而NH3H(CH3)2SiX和NH3-(CH3)3SiX系列两种方式都不能进行加成;在同系列加成产物中,以X=Cl时所得加成物最稳定.讨论了所有加成物中各键的性能、NBO电荷变化、取代基对加成物结构和稳定性的影响,并对H3SiX(X=F、Cl、Br、D与NH3及N(CH3)3加成物在有机溶剂中导电的可能性进行了讨论.     

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%.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.