微通道反应器在合成反应中的应用

微流控学(microfluidics)是在微米级结构中操控纳升至皮升体积流体的技术与科学,是近10年来迅速崛起的新交叉学科.流体在微流控芯片微米级通道中,由于尺度效应导致了许多不同于宏观体系的特点,例如分子间扩散距离短、微通道的比表面积大、传热和传质速度快等,促进了微流控芯片在有机合成反应中的发展.本文总结了微通道反应器的特点、微通道反应器中常用的流体驱动技术和微通道中流体的混合技术.通过一系列在微流控芯片中进行的有机合成反应,包括液-液均相反应、催化反应、相转移反应和异常激烈的有机合成反应等,进一步说明了微通道反应器同时具有微量和连续流动的优点.微通道反应器的发展不但在合成路线的优化方面有重要意义,而且有助于相关化学工业过程的改进.     

微流控技术在纳米合成中的应用

微流控技术具有微型化、集成化的特点,且所合成产物形貌和单分散性好,已经越来越多的被应用于纳米材料的合成中。 本文对微流体技术在纳米材料合成中的应用做了系统的阐述。 对微流控芯片中流体流动、混合机理进行了介绍,并详细介绍了微流控芯片的制作工艺,展望了微流体技术在合成纳米材料中应用前景。     

微流控芯片液滴生成与检测技术研究进展

微流控芯片液滴技术是一种操控微小体积液体的新技术,既可实现高通量微观样本的生成及控制,也可进行独立液滴的操作.分散的微液滴单元可作为理想的微反应器,在生物医药中的药物筛选、材料筛选和高附加值微颗粒材料合成领域展现出巨大的应用潜力.液滴微流控芯片是利用流体剪切力的改变,使互不相溶的两相流体在其界面处生成稳定、有序的液滴,...     

微流控芯片上的免疫分析

近20年来,随着微流控芯片加工技术的不断发展,微流控分析已从一个概念发展为当前世界上最前沿的科技领域之一,微流控芯片上免疫分析的方法研究也取得重要进展。这些芯片包含传输流体的微通道和免疫分析程序中部分或全部的必要组件。微流控技术用于免疫分析在减少试剂用量、缩短分析时间、自动化等方面提高了分析性能。本文综述了微流控芯片上免疫分析的发展、分类,并评述了各类微流控免疫分析芯片的性能及优缺点。     

惯性效应在微流控芯片中的应用

作为一种操控粒子或流体的新技术,基于流体惯性的操控技术已被应用于微流控芯片中粒子的输运、分选、聚焦及试样的混合和反应等操作,而在微尺度惯性效应基础上的惯性微流控芯片由于具有高通量、无需外场介入、低成本、易集成及微型化等众多优点,可用于解决医疗诊断、生化分析、合成化学及环境监测等领域的检测分析和微量操控问题,因此对该技术的机理及应用研究已成为目前微流控技术领域一个重要的研究热点。本文在介绍惯性微流控芯片机理及其研究进展的同时,从惯性聚焦、惯性分选及基于Dean流的微混合器和微流控光学器件等几个方面对惯性微流控芯片的最新应用研究进展进行了较为详细的介绍和分析比较。在此基础上,分析了惯性微流控芯片的局限和未来需要解决的问题。     

热压聚合物微流体芯片成型过程的温度场有限元模拟研究

热压法(Hot embossing)是一种快速复制微流控芯片的技术.它是生产高质量、高精度聚合物材料微流体芯片的一种方法.     

基于微流体脉冲驱动控制技术的电化学微流控芯片制备方法

基于微流体脉冲驱动控制技术搭建了电化学微流控芯片的制备系统.首先将纳米银墨水和甘油溶液分别微喷射到玻璃基底表面形成微电极图形和微流道液体阳模图形;然后分别进行烧结和聚二甲基硅氧烷(PDMS)模塑工艺制得微电极和微流道;最后将微电极和微流道键合形成电化学微流控芯片.研究了系统参量对液滴产生的影响以及液滴直径和重叠率对液滴成线的影响,制得的微电极最小线宽为45 μm、厚度为2.2 μm、电阻率为5.2 μΩ·cm,制得的微流道最小线宽为35 μm,流道表面光滑.采用制得的电化学微流控芯片进行了葡萄糖浓度的电化学流动检测.结果表明,葡萄糖溶液的浓度与响应电流具有较高的线性关系,可对一定浓度范围内的葡萄糖溶液进行定量检测.基于微流体脉冲驱动控制技术的电化学微流控芯片制备方法具有微喷射精度高、重复性好,制备系统结构简单、成本低廉等优点,可用于生化分析、生物传感器等领域的芯片制备.     

微型混合器的结构设计及实验研究

微流体系统包括微量流体的传感、输送、检测和控制^[1],是MEMS的一个重要分支.微型混合器是实现不同试剂或试样分子级混合的微流控器件系统,混合处理的目的是降低非均匀性.     

微流控床边检验系统的流体操控方法研究进展

综述了近年来面向床边检验应用的微流控分析仪器的研究进展.针对仪器微型化过程中所面临的流体操控自动化的发展瓶颈,以流体操控方式对当前床边检验分析系统进行了分类.评述了适用于现场床边检验应用的各类流体操控方式的优缺点及适用范围,并展望了微流控床边检验分析系统的发展方向和前景.     

微流控阻抗流式细胞仪在单细胞检测中的应用

单细胞水平的检测能够在细胞群中分辨出稀有的异常细胞,在生物医学领域如疾病的早期诊断和治疗评估等方面有着至关重要的作用.通过整合微流控技术、电阻抗技术与流式细胞术,微流控阻抗细胞仪能够在微流体精确操控条件下,实现流动态单细胞的连续、无损阻抗检测.与传统的单细胞检测方法相比,微流控阻抗细胞仪具有非标记、多参数、低污染和检测...     

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.