毛细管色谱法同时测定异戊二烯中环戊二烯、甲基吡咯烷酮和二甲基甲酰胺

用毛细色谱法建立异戊二烯中各组分定性分析方法及环戊二烯,N-甲基吡咯烷酮,N,N-二甲基甲酰胺的测定方法。气相色谱条件:采用OV-1701毛细管气相色谱柱,50 m×0.32 mm×0.53μm。程序升温60℃保持5 min后,以10℃/min升至190℃,保持3 min。氮气(纯度99.999%)为载气,柱前压为69 kPa。分流进样,分流比1∶100。进样口温度200℃,FID检测器,检测器温度为200℃。结果表明,异戊二烯中各组分均达到良好分离。环戊二烯、N-甲基吡咯烷酮、N,N-二甲基甲酰胺的线性范围均为0.5~1 200μg/mL;回收率分别为96.0%~98.5%,95.0%~102%,96.0%~99.6%;检出限均达到0.5μg/mL。其方法简单、快捷且灵敏度高,可以用于异戊二烯中杂质含量的控制。     

Selective elution of tea catechins and caffeine from polyvinylpolypyrrolidone

Desorption of catechins and caffeine from polyvinylpolypyrrolidone (PVPP) was comprehensively investigated. The result showed that caffeine could easily be desorbed from PVPP by the tested solvents except n‐hexane, while catechins could only be thoroughly done by dimethyl sulphoxide (DMSO) and N, N‐dimethylformamide (DMF). Excellent desorption efficiency of DMSO and DMF might be attributed to their high dipole moments and H‐bond potentials. Addition of ethanol was recommended considering the elution efficiency and fluidity, but ethanol volume should be <40% (v/v) for DMSO or 20% (v/v) for DMF. Desorption would get to equilibrium within 1 h and followed the pseudo‐second‐order model. Caffeine and catechins could be separately desorbed through two‐stage elution procedure, that is, water or 20% aqueous ethanol for desorbing caffeine and part of nongalloylated catechins and DMSO/ethanol (8/2, v/v) for eluting the remaining catechins. Highly purified catechins (~95%) with high level (~70%) galloylated catechins would be achieved when the desorption procedure was applied in column chromatograph.     

The electroreduction of alkyl iodides and polyiodides: The kinetic model of EC(C)E and ECE-EC(C)E mechanisms with included transfer coefficient variability

The cyclic voltammetry electroreduction of seven alkyl iodides was investigated in 0.3 M TBAP/DMF on glassy carbon electrode. The influence of carbon chain length and the number of iodine atoms in the molecule was examined. The two-electron reductive cleavage with iodine elimination was numerically resolved into one-electron consecutive steps. The mechanism of the process was discussed applying the mathematical EC(C)E and ECE-EC(C)E kinetic models with included transfer coefficient variability for one stage electroreduction of RI and two stage electroreduction of RI₂, respectively. For electroreduction of diiodomethane the discrimination of elementary alpha parameter between two reduction stages was determined.     

Viscosities of Nonelectrolyte Liquid Mixtures Containing Acrylonitrile

The measurements of viscosity are reported for seven binary mixtures of acrylonitrile (AN) with ethanenitrile (EN), methyl acetate (MA), ethyl acetate (EA), n-butyl acetate (BA), dimethylformamide (DMF), dimethylacetamide (DMA), and dimethyl sulphoxide (DMSO) at 303.15 K temperature. The viscosity data have been correlated with the equations of Grunberg and Nissan; Hind, McLaughlin, and Ubbelohde; Tamura and Kurata; Katti and Chaudhri; McAllister; Heric and Brewer; and of Auslaender. The relations between the viscosity deviations , excess Gibbs energy of activation G*^E of viscous flow, and the intermolecular interaction in these mixtures are discussed.     

二甲基甲酰胺新合成工艺的研究

对以氯油和二甲胺为原料制取二甲基甲酰胺的新工艺进行了研究，通过正交试验对工艺条件进行优化，得到的最佳工艺条件为：反应温度50℃、投料时间30min、保温时间30min、二甲胺过量5％。在此条件下，二甲基甲酰胺的产率为93．3％。     

溶解乙炔气瓶安全运输要点

介绍了乙炔的特性，并根据其特性提出运输溶解乙炔气瓶时，如何保护汽车驾驶员、押运员、装卸人员以及沿途群众和建筑物等安全运输要点。     

二甲基甲酰胺法丁二烯抽提工艺技术

简介了国内外二甲基甲酰胺法丁二烯抽提工艺技术的发展现状。建议国内应以降低能耗、提高自动化水平为其发展方向。     

Gelation of poly(vinyl alcohol)/water/dimethylformamide solutions and properties of dried films

The properties of solutions for syndiotacticity-rich poly(vinyl alcohol) (s-PVA)/dimethylformamide (DMF)/water systems, the gelation of the s-PVA solutions, and the properties of the dried s-PVA gel films were examined. From the results of the dissolution temperature of the polymer, the gelation temperature of the solutions, the melting temperature of the gels, and the compressive modulus of the gels, the solubility of the polymer was the highest at DMF contents of 10–20 vol %. The maximum dynamic tensile modulus of the drawn (×18) films obtained from the dried gel films with a DMF content of 10 vol % was 54.9 GPa at 20°C. The orientation of the polymer chains in the amorphous regions was higher than that in the crystalline regions. The orientation of the polymer chains in the amorphous regions for the drawn films with a DMF content of 10 vol % was higher than that for the drawn films with a DMF content of 60 vol %. The orientation of the polymer chains in the amorphous regions was considered to play an important role in the properties of high strength and high modulus. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1661–1667, 1998     

废LED封装中稀贵金属的有机溶剂法分离与富集

随着发光二极管(light-emmitting diode, LED)产品的广泛使用以及电子技术的快速发展,未来必将产生大量废LED有待处理,废LED中含有的稀贵金属Au、Ga具有极大的回收价值与潜力。围绕废LED中稀贵金属Au、Ga的分离与富集问题,提出采用二甲基甲酰胺溶剂法对废LED中的金属进行分离与富集。研究结果显示,当反应温度为150℃,反应时间为50 min,搅拌转速为300 r/min,液固比为15 mL/g时,采用纯二甲基甲酰胺作为反应体系可实现Au、Ga的高效分离与富集,金属Au、Ga的分离富集率分别为72.8%和93.5%,富集所得样品中金属Au、Ga的浓度相较于LED封装中的初始浓度分别富集2.3和2.9倍。     

碳五与二甲基甲酰胺+离子液体二组分物系汽液平衡数据的测定与关联

采用小型气相循环釜测定了不同离子液体1-戊烯对异戊二烯的相对挥发度(α12)的影响;在101.3 kPa下,测定了异戊二烯、1-戊烯、2-甲基-1-丁烯和环戊烯与二甲基甲酰胺(DMF)+1-己基-3-甲基咪唑六氟硼酸盐([hmim]PF6)4个二组分物系的汽液平衡数据;用NRTL方程对汽液平衡数据进行了关联。实验结果表明,[hmim]PF6对α12影响最大;适宜的[hmim]PF6用量为其在DMF中的含量为4%(w);4个二组分物系的汽液平衡数据符合热力学一致性检验;用NRTL方程对4个二组分物系进行计算,温度的最大偏差为1.59℃,汽相摩尔分数最大偏差为0.016 4,NRTL方程可用于碳五-DMF+[hmim]PF6物系的热力学数据的计算。