碱性离子液体催化甘油合成1,2-甘油碳酸酯(英)

以离子液体为催化剂,在无溶剂体系中,考察了生物质平台化合物甘油转化1,2-甘油碳酸酯的反应.与酸性离子液体和常用无机碱性催化剂相比,碱性离子液体咪唑基1-丁基-3-甲基咪唑([Bmim]Im)、氢氧化1-丁基-3-甲基咪唑([Bmim]OH)、咪唑基1-烯丙基-3-甲基咪唑([Amim]Im)、氢氧化1-烯丙基-3-甲基咪唑([Amim]OH)在甘油与碳酸二甲酯的酯交换反应中表现出优异的活性.其中,以[Bmim]Im离子液体为催化剂时甘油转化率为98.4%和甘油碳酸酯选择性接近100%.另外,该离子液体可以回收重复利用3次后甘油转化率仍可达92%,甘油碳酸酯选择性可近100%.此碱性离子液体催化方法具有反应结果较好、产物分离简单、条件温和以及环境友好等特点.     

新型碱性离子液体催化酯交换合成生物柴油

两步法合成了吗啉阴离子型碱性离子液体1-丁基-3-甲基吗啉盐[Hnmm]Im,经1 H-NMR和FT-IR分析确认了离子液体中间体的结构,并通过阴离子交换得到碱性离子液体,对该离子液体在酯交换制备生物柴油反应中的催化性能进行了研究。结果表明,该碱性离子液体[Hnmm]Im具有较高的酯交换催化活性,在60℃、催化剂用量为3%、醇油物质的量比为6.5∶1.0、反应2 h的条件下,产物脂肪酸甲酯(FAME)含量可达95.80%。而且该离子液体的催化稳定性较好,重复使用5次后仍有较高的催化活性。     

新型双功能交联型阴离子交换膜的制备与性能

以2-甲基咪唑为原料合成2种离子液体前驱体1-烯丙基-2-甲基咪唑和1-丁基-2-甲基咪唑,以苯乙烯(St)和对氯甲基苯乙烯(VBC)为原料制备聚离子液体主链p(St-co-VBC),2种离子液体前驱体与聚离子液体主链发生季铵化反应铸膜,制备了交联结构和梳型侧链结构型阴离子交换膜(AEMs).通过傅里叶红外光谱、扫描电子显微镜和热重分析等考察了阴离子交换膜的结构、微观形貌、氢氧根离子传导率、热稳定性及碱性稳定性等性能.结果表明,AEMs含水率为36.7%~93.4%,离子交换容量为1.61~2.16 mmol/g,80℃时,p(St-co-VBC)-3型AEMs氢氧根离子传导率高达68.4 mS/cm,在1 mol/L NaOH溶液中碱性浸泡240 h后,氢氧根离子传导率仍高达52.2 mS/cm,具备良好的碱性稳定性.     

新型氨基功能化碱性离子液体1-(2-氨基乙基)-3-甲基咪唑咪唑盐催化四类取代2-氨基-4H-色烯衍生物的合成

设计合成了阴阳离子均具有碱性位点的新型氨基功能化碱性离子液体1-(2-氨基乙基)-3-甲基咪唑咪唑盐([2-aemim]im,3),经ESIMS和1H NMR确定了结构.[2-aemim]im的碱性与氨基功能化的阳离子([2-amim]+)有关,但主要取决于咪唑阴离子(im-).TG-DSC分析显示[2-aemim]im具有高的热稳定性.将[2-aemim]im用于催化水相介质中芳香醛、丙二腈和酚的三组分一锅法反应制备2-氨基-4H-色烯衍生物,阴阳离子之间表现出协同促进催化作用.该催化剂具有高效和底物作用范围广的特点,应用不同的酚类及类似物,如1-萘酚、2-萘酚、间苯二酚和环己二酮,以高产率得到了相应的不同官能团取代的2-氨基-4H-苯并[h]色烯(4a～4e),2-氨基-4H-苯并[f]色烯(5a～se),2-氨基-4H-色烯(6a～6e)和2-氨基-4H-四氢色烯(7a～7e)四类2-氨基-4H-色烯衍生物.离子液体至少可以循环使用5次,催化活性无显著降低.     

咪唑根碱性离子液体在水介质Knoevenagel反应中的催化作用

报道了咪唑根1-丁基-3-甲基咪唑([Bmim]Im)碱性离子液体的合成与表征,该离子液体具有强碱性和较好的热稳定性.碱性离子液体[Bmim]Im用于催化水介质中Knoevenagel反应,发挥了碱催化剂与相转移催化剂双重作用.此外,离子液体[Bmim]Im及其水溶液还具有良好的循环使用性能.水介质、低催化剂用量、室温...     

Brønsted双核碱性离子液体的合成及其在制备生物柴油过程中的催化性能

以N-甲基吗啡啉和1,4-二溴丁烷为原料,通过两步法合成了新型Brønsted碱性双核离子液体.分别采用¹H-NMR、FT-IR和元素分析对合成的离子液体进行结构分析;采用TGA测试离子液体的热稳定性;同时测定了离子液体的溶解性和碱性.此外,考察了双核碱性离子液体在大豆油和甲醇酯交换反应中的催化活性.结果表明,当甲醇:大豆油=14:1(物质的量比)、离子液体用量为大豆油质量的5%、反应时间5 h、反应温度60 ℃时、生物柴油收率为 95.6%(质量分数),且离子液体经回收、真空干燥,重复使用6次后催化活性没有明显降低,仍能达到94%以上.     

1-烷基-3-甲基咪唑硫酸氢盐系列离子液体的热力学性质

在293.15~343.15 K温度范围内,用MYX-1密度计测定了系列离子液体 1-丁基-3-甲基咪唑硫酸氢盐[C4mim]HSO4 (1-butyl-3-methylimdazolium hydrosulfate)、1-己基-3-甲基咪唑硫酸氢盐[C6mim]HSO4 (1-hexyl-3-methylimdazolium hydrosulfate)、1-辛基-3-甲基咪唑硫酸氢盐[C8mim]HSO4 (1-octyl-3-methylimdazolium hydrosulfate)、1-癸基-3-甲基咪唑硫酸氢盐[C10mim]HSO4 (1-decyl-3-methylimdazolium hydrosulfate)的密度。利用不同温度下的密度值计算得出了离子液体的热膨胀系数及分子体积。利用Glasser经验方程计算了离子液体的标准熵和晶格能,并进一步对其热力学性质进行了讨论。     

新型碱性离子液体催化酯交换合成生物柴油

两步法合成了吗啉阴离子型碱性离子液体1-丁基-3-甲基吗啉盐Im,经 ¹H-NMR和FT-IR分析确认了离子液体中间体的结构,并通过阴离子交换得到碱性离子液体,对该离子液体在酯交换制备生物柴油反应中的催化性能进行了研究。结果表明,该碱性离子液体Im具有较高的酯交换催化活性,在60 ℃、催化剂用量为3%、醇油物质的量比为6.5：1.0、反应2 h的条件下,产物脂肪酸甲酯（FAME）含量可达95.80%。而且该离子液体的催化稳定性较好,重复使用5次后仍有较高的催化活性。     

离子液体[2-aemim]im催化Knoevenagel反应和异噁唑酮合成

以碱性离子液体1-(2-氨基乙基)-3-甲基咪唑咪唑盐([2-aemim]im)作为催化剂,催化Knoevenagel反应和4-芳亚甲基异噁唑-5(4H)-酮衍生物的合成。实验结果表明:在无溶剂条件下,该离子液体对Knoevenagel反应具有很高的催化活性,一系列芳香醛和活泼亚甲基化合物的反应在室温条件下2 min内顺利完成,均以90%以上的高产率生成取代烯烃产物.将该碱性离子液体用于催化乙酰乙酸乙酯或苯甲酰乙酸乙酯、盐酸羟胺和芳香醛三组分一锅法缩合制备4-芳亚甲基异噁唑-5(4H)-酮衍生物,具有反应时间较短、产率较高和后处理简单的特点。离子液体经简单处理后能多次循环使用。     

N-辛基-2-吡咯烷酮甲磺酸盐离子液体动态涂敷毛细管电泳分离碱性蛋白质

研究了新型吡咯烷酮类离子液体N-辛基-2-吡咯烷酮甲磺酸盐([NOP]~+CH_3SO~-_3)作为毛细管动态涂敷试剂时,对3种常见碱性蛋白质标准物质(溶菌酶、细胞色素c、α-胰凝乳蛋白酶原)的分离情况。系统考察了缓冲溶液类型、缓冲溶液p H值、离子液体添加剂浓度对分离效果的影响。结果表明,该动态涂敷方法简单快速,3种碱性蛋白质在8min内实现了高效分离,理论塔板数分别为2.9×10~5、5.8×10~5、1.8×10~4N/m。     

Copolymers of tetrafluoroethene with chlorotrifluoroethene and with bromotrifluoroethene

Tetrafluoroethene (TFE)–chlorotrifluoroethene (CTFE) and TFE–bromotrifluoroethene (BTFE) copolymers have been synthesized by solution copolymerization over the entire range of comonomer composition. Crystallinity data are reported and first- and second-order transitions have been investigated by DSC. Glass transition temperatures of TFE-CTFE copolymers vary in a nonlinear fashion in the range defined by the homopolymers conforming best to the Johnston equation; the behavior in the TFE-BTFE system is more linear. Whereas TFE-BTFE copolymers show a steep decrease of melting temperature at higher BTFE content, due to the amorphous character of the polymers, more regular behavior was found for TFE-CTFE copolymers. Enthalpies of fusion are also reported. The results are discussed in relation to copolymer composition and structure and are compared with data on tetrafluoroethene–hexafluoropropene (FEP) fluorocarbon resins.     

Asymmetric sorbents with N-carboxymethyl-L-valine and with N-carboxymethyl-L-aspartic acid

Conclusions The asymmetric sorbents with N-carboxymethyl-L-valine with N-carboxymethyl-L-aspartic acid can be used to resolve racemates by the ligand-exchange chromatography method. Institute of Heteroorganic Compounds, Academy of Sciences of the USSR, Moscow. Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2378–2380, October, 1976.     

Reactions of indole derivatives with cardioprotective activity with reactive oxygen species. Comparison with melatonin

We have previously reported on the synthesis of novel indole derivatives containing an amine-triazole moiety (1a-d, 2a-c), and their antioxidant activity on in vitro non-enzymatic rat hepatic microsomal lipid peroxidation. Some of the compounds showed protective activity against oxidative injury of ischemic myocardium. In the present paper we investigated the interactions of these derivatives with reactive oxygen species, in order to find a mechanism of their antioxidant capacity and to identify structural characteristics responsible for these properties. These interactions were compared with melatonin, which is also an indole derivative. The antioxidant profiles of the compounds were established by different in vitro protocols as follows: 1) by the interaction of the compounds with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable free radical, 2) their scavenging effects on superoxide anions using an enzymic system of xanthine-xanthine oxidase, 3) their inhibitory effects on xanthine oxidase and 4) their ability to scavenge hydroxyl radicals by comparison with dimethyl sulfoxide (DMSO) for *OH. All compounds were found to interact with DPPH, most of them to be superoxide anion scavengers and to be strong hydroxyl radical scavengers. Derivatives 1a and 1d substituted on the nitrogen of the indolic nucleus were found to have better antioxidant properties than the reference compounds used and melatonin.     

Voltammetry with a Fluoride-Selective Electrode with Solid-Phase Reference System

Experimental results obtained in a study of the voltammetric response of an all-solid fluoride-selective electrode based on LaF₃ (Eu²⁺ 0.8 mol %), LaF₃ (Sr²⁺ 5 mol %) and CeF₃ (Sr²⁺ 5 mol %) single crystals brought in contact with Ag, Bi, and Sn metal samples are presented. The method of cathodic inversion voltammetry was applied to study the reduction of La³⁺ and Ce³⁺-cations from the rigid sublattice of solid electrolytes, which determines the threshold of the electrochemical stability of a membrane. Anodic inversion voltammetry was used to investigate the characteristics of solid-phase generation of metal fluorides at the interface between the fluoride-selective electrode and metals.     

Microfibrillated cellulose with sizing for reinforcing composites with LDPE

Microfibrillated cellulose (MFC) fibers were acylated by the sizing agent, alkenyl succinic anhydride (ASA) reagent in an aqueous medium, by simple impregnation. The chemical modification was confirmed by Fourier transform infrared spectroscopy and solid-state ¹³C NMR. All the samples were combined with low-density polyethylene and the morphology, thermal properties, mechanical properties and water absorption behavior of the ensuing composites were investigated. The chemical modification of the MFC with ASA improved the interfacial adhesion with the matrix and hence the mechanical properties of the composites while decreasing their water uptake capacity. In addition, it was shown that the degree of substitution strongly influenced the performance of the composites.     

Reaction of isatin with alkylating agents with acidic methylenes

The reaction of isatin (1) with different alkyl halides 2 and alkaline carbonates in aprotic polar solvents leads mainly to N-alkyl derivatives 3. The use of alkylating agents that have acidic methylenes leads to competitive formation of the corresponding epoxide 5. The formation of 5 is favored by low-polarity solvents at low temperatures and strong bases. Epoxides 5c, d obtained using NaEtOH/EtOH at 0–5 °C are transformed into the corresponding 4-quinolinones 6 at higher temperatures. The use of Ag₂CO₃ allows obtaining compounds 3 as major products, along with varying amounts of labile O-alkyl derivatives 4 and dimerization products.     

Multielement analysis with ICP-AES-possibilities for quality control with CRMs

Summary An analysis using Certified Reference Materials (CRMs) together with routine samples is by far the best approach for quality control in multielement analysis of environmental samples. The selection of the correct CRM is thus the first important step for all reliable analysis. The chosen material should have a similar matrix, similar concentration of the element(s) of interest and a sufficient number of well-certified elements. For the analysis of samples from the Environmental Specimen Bank only a few CRMs could be successfully used. These were analyzed for a considerable period of time, together with the routine samples for quality control. The results of these analyses were compared with the certified values.     

Fluorination with xenon difluoride. Reaction with halogenated hydrocarbons

Filler and coworkers [1-5] have demonstrated the utility of xenon difluoride as a selective fluorinating agent for aromatic hydrocarbons in the liquid phase, while Mackenzie and coworker [6] have fluorinated aromatic compounds in the vapour phase. We have developed a fluorination reaction of phenyl substituted olefins resulting in high yields of vicinal difluorides [7,8] and trifluoroacetates, depending on the catalyst. In our continued interest in the use of xenon difluoride as a mild fluorinating agent for fluorination of organic compounds, we have tries to fluorinate some heterocyclic ring systems, e.g. imidazo-(1,2-b)-pyridazine, under conditions similar of those used for fluorination of phenyl substituted olefins [7,8,9] (room temperature, methylene chloride as solvent, hydrogen fluoride as catalyst). It is well known that heteroaromatic compounds are less reactive toward electrophilic substitution reactions then aromatic hydrocarbon systems. However, it has been shown that bromination of imidazo-(1,2-b) -pyridazine results in 3-bromo products [10], while in chlorination with phosphorus pentachloride [11], the entering order of chlorine atoms is at position 3 > 2, 7 > 8 > 6 (Radical reactions).