一种高选择性的检测丙酮蒸气催化发光传感器

设计了一种基于纳米材料SrCO3中掺杂Dy2O3的催化发光(CTL)丙酮蒸气传感器。通过掺杂Dy2O3使体系选择性显著提高。当Dy2O3的掺杂量为33%时,催化发光强度是不掺杂的3倍。当各测试气体浓度均为2000mL/m3时,三氯甲烷、二氯乙烷、甲醛和苯气体不干扰丙酮的测定。乙醇和正丁烷只引起15%和2.1%的干扰。在温度383℃、波长425nm、空气流速为360mL/min的最佳条件下,催化发光强度与丙酮蒸气浓度在1.0～5000mL/m3内呈良好的线性关系,检出限为0.30mL/m3。本传感器响应和恢复时间快速。     

复合ZrO2/MgO催化发光丙烯醛气体传感器

设计了基于在纳米ZrO2中掺杂Mg0的催化发光传感器,以快速检测丙烯醛气体.与纯ZrO2相比,MgO的掺杂量为5%时,丙烯醛的催化发光强度增大了1.8倍,干扰气体乙醛的催化发光强度降为原来的约1/7.传感器在波长425 nm,温度279 ℃,流速200 mL/min条件下,对丙烯醛具有高灵敏度和选择性,发光强度与丙烯醛...     

基于纳米复合氧化物催化发光的乙醇传感器

基于纳米材料上乙醇的催化发光现象,建立了直接测定空气中乙醇浓度的方法.实验发现,乙醇在纳米级钛锆镧(原子比为5∶2∶1)复合氧化物表面有较高的发光强度和较好的选择性,以此为敏感材料可以建立一种高效稳定的乙醇气体传感器,其最佳操作条件为:分析波长620nm,测定温度310℃,载气流速130mL/min.方法的检测限为(3σ)1.3mg/m3,线性范围为2～230mg/m3,相关系数为0.9990,回收率为97.4%～102.7%.对常见共存物的研究发现,甲醛、丙酮、苯、氨、二氧化硫和二氧化碳都不干扰测定,该传感器的连续工作时间可达120h以上.     

基于纳米Co3O4低温催化发光的乙醚传感器

基于纳米Co3O4材料上乙醚的催化发光(CTL)现象,建立了直接测定空气中乙醚浓度的方法.研究发现,在较低温度下,乙醚在球链状的纳米Co3O4表面具有很高的发光强度和较好的选择性,以此为敏感材料就可以建立一种高效稳定的乙醚气体传感器.其最佳操作条件为:测定温度176℃,分析波长440 nm,载气流速180 mL/min.乙醚气体在4.0～1500 ppm(φ)的浓度范围内呈良好的线性关系(R=0.9993),响应时间为2 s,检出限为φ=1.67 ppm(3σ),回收率为97.3%～103.0%.考察了11种相同浓度的常见挥发性有机物的干扰情况,发现除丙酮、乙醇、四氯化碳和乙酸乙酯有轻微干扰(小于0.8%),其余7种物质均未产生明显的CTL信号.连续140 h通过150 ppm(φ)的乙醚气体,发光强度无明显降低,表明该传感器是一种长寿命的、性能稳定的传感器.     

基于氧化钛-氧化钇粉体催化发光甲醛气体传感器的研究

研究了甲醛在TiO2-Y2O3(质量比为3∶1)粉体表面催化发光行为,发现基于这种催化剂的气体传感器对甲醛的检测具有高灵敏度和较强的选择性。在波长490 nm处进行定量分析,催化发光强度与甲醛浓度在一定范围内呈良好的线性关系,其线性范围为0.08~40 mL/m3(r=0.9991,n=6);检出限为0.03 mL/m3(S/N=3)。外来物质如环己烷、正己烷、三氯甲烷、苯、乙醇、甲醇、乙醛、氨、水蒸气等与甲醛共存时,除了乙醇和氨分别引起干扰外,水蒸气与其它气体不干扰测定。该传感器工作时间可达80 h以上,是一种长寿命的、性能稳定的气体传感器,并成功地实现了对甲醛的实时在线检测。     

基于CeO2-Co3O4纳米纤维的催化发光式甲醛传感器研究

采用双喷嘴静电纺丝法制备了CeO2-Co3 O4纳米纤维,将制备的CeO2-Co3 O4纳米纤维均匀涂覆于 ω型加热线圈表面形成催化发光薄膜,设计了一种新型催化发光甲醛传感器.采用X射线衍射仪、 扫描电子显微镜、 全自动程序化学吸附仪和X-射线光电子能谱仪,表征了Co3 O4-CeO2纳米纤维的相组成和微观形貌,讨论了甲醛在CeO2-Co3 O4催化剂表面的电化学特性和催化发光机理.在优化条件下,即波长500 nm、 温度550℃ 、 载气流速0.2 L/min,甲醛传感器件(Ce30)催化发光强度与甲醛浓度在1.2~50μg/m3范围内有良好的线性关系,灵敏度为40.04 a.u./(μg/m3),检出限为1.2μg/m3,动态响应和恢复时间分别为2.4和3.5 s.此传感器可用于汽车尾气中甲醛浓度检测,相对误差范围为0.4%~1.1%,相对标准偏差RSD<3%(n=6).     

γ-Fe_2O_3纳米纤维的丙酮敏感特性

采用静电纺丝法制备了PVP/FeC6H5O7复合纳米纤维,并将复合纤维在500℃高温烧结3 h,X射线衍射分析(XRD)表明,烧结后的产物为正尖晶石结构的γ-Fe2O3晶体.扫描电子显微镜(SEM)观测结果表明,制得了直径均匀、连续的复合纳米纤维,其平均直径约为1000 nm;烧结后的γ-Fe2O3纳米纤维保持了其连续性,但纤维发生了收缩,直径较烧结前小,平均约为600 nm.比表面积分析表明,γ-Fe2O3纳米纤维比表面积为57.18 m2/g.气敏性能测试结果表明,230℃为γ-Fe2O3纳米纤维检测丙酮气体的最佳工作温度.在此温度下,γ-Fe2O3纳米纤维对丙酮气体表现出高响应度[S=6.9,c(Acetone)=7.88×104mg/m3]和线性度(7.88×102~1.58×105mg/m3浓度范围内).同时,γ-Fe2O3纳米纤维气体传感器件还表现出良好的长期稳定性.     

基于硼酸镝催化发光法的正丙醇气体传感器的研究

基于正丙醇在硼酸镝材料表面有强烈的发光现象,设计了以硼酸镝为传感材料检测正丙醇的传感器。该传感器在波长为535 nm、温度为150℃、载气流速为200 m L/min时,测定正丙醇质量浓度工作曲线的线性范围为40~1800 mg/m~3(R=0.9955),检出限为15 mg/m~3。选择了13种干扰气体(丙酮、二甲苯、正己烷、三氯化碳、丙醛、乙醛、四氯化碳、苯、异丙醇、二氯化碳、甲醇、乙醇、正丁醇)进行选择性测试,除二氯化碳、乙醇、正丁醇分别有4%,9%,5%左右的干扰外,其他气体并无干扰。连续通入45 h 300 mg/m~3的正丙醇,发光强度无明显变化,传感器具有良好的使用寿命。     

检测易爆气体的催化发光传感器研究

报道了一种用于定量分析易爆气体混合物丙烷和异丁烷的基于碳酸锶纳米材料的催化发光传感器.基于该传感器在不同温度下对两种气体的灵敏度不同,在320℃和342℃两个工作温度下,两种气体的浓度范围均为1000 mL/m3～10000 mL/m3时,分别建立了混合组分浓度相对催化发光强度的两个线性回归方程.在342℃时,丙烷和异丁烷的检出限(3σ)分别为50 mL/m3和20 mL/m3.可通过解上述两个联立方程式求得未知混合物中两组分的浓度.外来物质甲烷、乙烷、CO、氨气通过传感器时,甲烷和乙烷分别引起5.6%和17.2%的干扰,其它气体不干扰测定.20000 mL/m3的水蒸气不干扰2000 mL/m3丙烷和异丁烷气体的测定.用该法分析了人工合成样品中两种气体的浓度.     

基于稀土材料催化化学发光法检测乙腈气体传感器的研究

基于稀土粉体材料Y2O3催化乙腈气体在其表面发生氧化反应而产生化学发光现象,研制了一种基于化学发光原理检测乙腈的气体传感器。研究结果表明,该传感器具有较高灵敏度和较强的选择性。在温度175℃,波长490 nm条件下,其催化化学发光强度与乙腈浓度在一定范围内呈良好的线性关系,线性范围为2.9~290.0 mg/m3(r=0.9955);检出限为1 mg/m3。该传感器操作简便、性能稳定,实现了对乙腈气体的实时在线检测。     

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.