新溶剂法纤维素纤维的技术进展

传统的粘胶纤维存在源头污染问题,有必要开发符合环保和资源可再生要求的新溶剂法纤维素纤维生产技术,以作为未来纤维材料的大宗品种.在已开发的众多纤维素溶剂体系中,NMMO(N-甲基吗啉-N-氧化物)溶剂体系已形成了规模化生产;纤维素氨基甲酸酯、氢氧化钠或氢氧化锂/硫脲或锌酸钠或(和)尿素水溶液、离子液体溶剂体系的开发也取得了较大进展.以NMMO为代表的有机溶剂法纤维素纤维产业化工程技术中,连续真空薄膜推进溶解技术具有对比优势;纺丝技术均为干喷湿纺;溶剂回收技术的发展方向是提浓过程的高效蒸发并结合其它节能技术;原纤化控制技术在规模化生产中采用干燥前在线交联.     

成膜因素控制的SIS膜表面环境响应行为

利用和频振动光谱、原子力显微镜及接触角技术研究了不同成膜溶剂、制膜方式所得苯乙烯/异戊二烯/苯乙烯嵌段共聚物(SIS)膜的表面结构及其对溶剂蒸气的响应行为.发现环己酮为溶剂的浇铸膜及甲苯为溶剂的旋涂膜表面润湿性随环己烷和丁酮蒸气交替处理发生变化;甲苯和环己烷为溶剂的浇铸膜表面性质不随溶剂蒸气处理而变化.原因是不同制样条件所获SIS膜具有不同的初始相分离结构.当聚合物膜形成远离平衡态的相分离结构时,分子聚集态转变的能垒较低,易于在溶剂蒸气诱导下转变为新的结构.反之,则不利于链构象转变,形成不同的聚集态结构.这将导致不同制备条件所得SIS膜经溶剂蒸气处理后形成不同的表面结构,呈现出各异的环境响应行为.本研究为智能界面材料的设计和制备提供了新思路.     

顶空-气质联用法对醋酸纤维滤棒中溶剂残留的测定

利用顶空-气质联用仪(HS/GC-MS)建立了一种同时测定醋酸纤维滤棒中溶剂残留的测定方法.利用顶空气相色谱技术,用选择离子模式对醋酸纤维滤棒中溶剂残留进行了定量分析.分析结果表明,方法线性关系良好,相关系数均大于0.998 0,检出限为0.010 4~0.157 8 mg/kg.9种溶剂残留的平均回收率为90.3%~102.2%,相对平均偏差小于10%.方法适用于醋酸纤维滤棒溶剂残留的测定且高效、准确、简便.     

GC-MS/MS法测定沉积物和生物样品中邻苯二甲酸酯

采用固相萃取(SPE)和QuEChERS技术结合气相色谱-串联质谱(GC-MS/MS)技术,建立了养殖海域沉积物和生物样品中16种邻苯二甲酸酯(PAEs)定量分析方法.沉积物样品以二氯甲烷为提取溶剂,经PSA-Silica固相萃取柱净化,生物样品以乙腈为提取溶剂,经150.0 mg N-丙基乙二胺(PSA)、150.0...     

白钨矿型钨酸盐和钼酸盐纳米晶/微晶制备研究进展

综述近年来自钨矿型钨酸盐和钼酸盐纳米晶/微晶制备技术领域的研究进展,重点介绍熔盐法、有机配合物前驱法、模板法、微乳液法、水热法、溶剂热法和微乳液.溶剂热法的原理和技术特点,比较各种方法的异同点,并提出白钨矿型钨酸盐和钼酸盐纳米晶/微晶制备技术的发展趋势.     

溶剂性质对溶剂蒸气加速等规聚丁烯-1相转变的影响

以50℃等温结晶后的等规聚丁烯-1(PB-1)为研究对象,利用X射线衍射(XRD)和示差扫描量热技术(DSC)对不同溶剂蒸气处理的PB-1进行分析,并用原位XRD在线研究了溶剂熏蒸聚丁烯-1的Ⅱ-Ⅰ相转变过程.XRD与DSC结果表明除了水和醇类溶剂,其他大多数溶剂如正己烷、三氯甲烷、1,2-二氯乙烷、苯、甲苯、二甲苯、...     

离子对内电子转移型染料阴离子-鎓盐阳离子光敏体系中的溶剂效应和结构效应

本文研究了溶剂效应和结构效应对染料碘(钅翁)盐光物理,光化学性质的影响.观察到在溶剂中离子对可以各种形式存在,如紧密离子对、溶剂分隔离子对或溶剂化的自由离子.溶剂的极性不仅影响各种存在形式的光谱性质,而且影响它们之间的平衡关系,进而影响离子对体系的物理化学性质.染料母核和碘(钅翁)阳离子的结构均对离子对体系的性质有影响.光诱导电子转移反应的热力学驱动力越大,反应速度越快.用分子模拟技术(Molecular Modeling)对离子对体系的立体结构进行了研究,为理解离子对体系的各种物理化学行为提供了重要的参考.     

铑膦配合物在烯烃醛化反应中溶剂效应的原位红外光谱研究

本文应用原位红外光谱技术,在接近于工业反应条件下(H_2:CO=1:1.1.0MPa.80℃),在四种溶剂(异丁醛、2—乙基已醇、甲苯和环已烷)中考察了铑膦配合物催化剂Rh(acac)(CO)(PPh_3)的烯烃醛化反应.检测到在四种溶剂中的主要中间配合物均为HRh(CO)_2(PPh_3)_2,但在2—乙基己醇溶剂中的烯烃醛化反应速度高于异丁醛、甲苯和环已烷溶剂(约1.2～1.3倍).结果表明,采用2—乙基已醇溶剂替代醛类做反应溶剂,有可能提高工业反应装置的生产能力.     

气相萃取-气质联用法测定上光工艺对烟标印刷溶剂残留的影响

利用顶空-气相色谱串联质谱(HS-GC/MS)技术建立光油溶剂残留控制物的测定方法,对比、分析光油种类、印版清洗剂、印版线数、印刷速度、干燥温度等工艺参数对上光工序中挥发性有机物(苯及苯系物、溶剂残留、溶剂杂质)的影响及变化.经仪器参数优化,各组分相关系数(R~2)均≥0.998 2;回收率≥80.4%,相对标准偏差(RSD)5.8%(n=6).结果表明,水性光油较珠光油、UV光油溶剂残留量最少,选择纯水和正丙酯溶液结合清洗印版引入溶剂残留量最小,随印版线数增加溶剂残留量不断增大,当印刷速度达160 m/min光油附着力最佳,溶剂残留量较少,干燥温度为120℃光油表现出彻干性,溶剂得到充分挥发.     

水溶性CoFe2O4磁性纳米粒子的制备和磁性研究

采用溶剂热法,分别以FeCl3· 6H2O和CoCl2·4H20为铁源和钴源,二甘醇和二乙醇胺为溶剂和配位剂,制备了水溶性CoFe2O4纳米粒子.采用TEM、XRD、FTIR光谱、热重-差热分析等技术对所得纳米粒子进行表征,并研究了材料的磁学性质.结果表明,这种铁酸钴纳米粒子具有超顺磁性,饱和磁化强度M.达53.2em...     

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.