MDA的乙酰化改性及其对合成聚脲性能的影响

以4,4＇-二氨基二苯甲烷（MDA）为原料,在冰乙酸和磷酸条件下一步合成得到新型位阻型扩链剂4,4＇-二乙酰胺基二苯甲烷（MMDA）,利用红外光谱和1H-NMR对其结构进行了表征,确定了合成产物的化学结构。将它和端氨基聚醚及4,4＇-二苯甲烷二异氰酸酯（MDI）合成新型聚脲,考察了MDA扩链剂改性对聚脲性能的影响。当MMDA代替MDA合成聚脲时,其凝胶时间由45 s增加到143 s。     

H12MDI型聚氨酯弹性体的制备及力学性能研究

以4, 4'–二环己基甲烷二异氰酸酯(H_(12)MDI)、聚醚多元醇等为主要原料,3, 3'–二氯–4, 4'–二氨基二苯基甲烷(MOCA)为扩链剂,采用预聚体法合成了聚氨酯弹性体,并研究了其力学性能。随NCO值提高,H_(12)MDI型聚氨酯弹性体的拉伸强度及硬度增加,伸长率降低;随MOCA量减小,拉伸强度和硬度均降低,伸长率提高。     

H_(12)MDI在PUE中的应用及其对PUE性能的影响

以4,4'-二环己基甲烷二异氰酸酯(H_(12)MDI)、高活性聚醚三醇(330N)、聚四氢呋喃醚二醇(PTMG)、聚己二酸丁二醇酯二醇(PBA)、1,4-丁二醇(BDO)、乙二醇(EG)为主要原料,辅以胺类和锡类催化剂,分别采用一步法和两步法(预聚体法)制备了聚氨酯弹性体(PUE)。研究了H_(12)MDI对PUE制备工艺特性及结构性能的影响,并采用FTIR、DSC、TG和XRD表征了PUE的结构、热性能以及结晶特性。     

4,4′-二氨基二苯甲烷合成的正交试验法研究

以苯胺、甲醛为原料在盐酸催化下合成4,4′-二氨基二苯甲烷。利用正交实验法考察了反应物投料比、转位温度、转位时间对4,4′-二氨基二苯甲烷收率的影响。确定了优化条件为:n(苯胺)∶n(甲醛)=4∶1,转位温度85℃,转位时间30 min。优化条件下所得目标产物收率为90.42%。     

4,4'-二苯甲烷二胺与碳酸二甲酯甲基化反应合成4,4'-双(二甲氨基)二苯甲烷

该文以4,4'-二苯甲烷二胺(MDA)与碳酸二甲酯(DMC)为原料合成4,4'-双(二甲氨基)二苯甲烷(MBDMA).用不同类型催化剂对反应过程中甲氧羰基化和甲基化反应进行了调控.NaY分子筛催化剂促进甲基化反应的发生,适宜的反应条件为:催化剂用量m(NaY):m(DMC)=0.07:1,反应物配比,n(DMC):n(MDA)=30:1,反应温度190℃,反应时间6 h,此时MDA完全转化,MBDMA选择性达97%.相反,乙酸锌催化剂则促进甲氧羰基化反应的进行.用高效液相色谱/质谱联用技术(HPLC/MS)对NaY催化下反应副产物的结构进行了分析,发现生成的副产物主要为3种不同程度的N-甲基化产物,表明MBDMA生成是经过逐步甲基化完成的.     

4,4′-二苯甲烷二胺与碳酸二甲酯甲基化反应合成4,4′-双(二甲氨基)二苯甲烷

该文以4,4′-二苯甲烷二胺(MDA)与碳酸二甲酯(DMC)为原料合成4,4′-双(二甲氨基)二苯甲烷(MBDMA)。用不同类型催化剂对反应过程中甲氧羰基化和甲基化反应进行了调控。NaY分子筛催化剂促进甲基化反应的发生,适宜的反应条件为:催化剂用量m(NaY)∶m(DMC)=0.07∶1,反应物配比n(DMC)∶n(MDA)=30∶1,反应温度190℃,反应时间6 h,此时MDA完全转化,MBDMA选择性达97%。相反,乙酸锌催化剂则促进甲氧羰基化反应的进行。用高效液相色谱/质谱联用技术(HPLC/MS)对NaY催化下反应副产物的结构进行了分析,发现生成的副产物主要为3种不同程度的N-甲基化产物,表明MBDMA生成是经过逐步甲基化完成的。     

催化加氢制备低反-反异构PACM用负载型Ru催化剂研究

采用浸渍法制备了不同载体负载钌催化剂，并考察其催化4,4’-二氨基二苯基甲烷(MDA)液相加氢制备反-反异构PACM性能，重点研究了第二金属助剂协同催化对催化剂综合性能的影响。结果表明，添加金属Re后催化剂活性、选择性均有明显提升，最优的Ru∶Re金属负载比例为5∶1,此时反-反异构体含量低于20%,且催化剂具有良好的稳定性。     

4,4'-二氨基二苯甲烷与碳酸二甲酯甲氧基羰基化制备4,4'-二苯甲烷二氨基甲酸甲酯

研究了4,4′-二氨基二苯甲烷(MDA)与碳酸二甲酯(DMC)甲氧基羰基化合成4,4′-二苯甲烷二氨基甲酸甲酯(MDC)的反应,研究了反应的影响因素,并采用FTIR、1 H NMR等测试方法对合成产物的结构进行了表征。结果表明,合成MDC的最佳反应工艺为反应温度160℃,用醋酸铅催化,且m(醋酸铅)∶m(MDA)=6%,反应物配比n(DMC)∶n(MDA)=20∶1,反应时间3h。在上述反应条件下,MDA的转化率达到100%,MDC的收率达到96.6%。     

4,4′–二氟二苯甲酮的合成进展

介绍了一种重要的含氟精细化工产品和医药中间体4,4′–二氟二苯甲酮的理化性质、光谱性质及应用。综述了4,4′–二氟二苯甲酮国内外的合成研究情况,其合成方法主要包括Fridel–Crafts烷基化水解法、Fridel–Crafts酰基化法、卤素置换法、重氮化氧化法、催化羰基化法、4,4′–二氟二苯二氯乙烯氧化法、4,4′–二氟二苯甲烷氧化法等。     

4,4''-二氨基二苯甲烷催化加氢研究与应用进展

综述了4,4′-二氨基二苯甲烷(MDA)催化加氢技术的研究进展。总结了该反应所用的不同催化体系的特点,分析了反应温度、压力、溶剂种类等因素的影响,讨论了不同类型反应器的特征,指出了MDA催化加氢反应的未来研发和应用方向。     

佛山市顺德新城区降水中污染物的监测和分析

为掌握佛山市顺德新城区降水中污染物的情况,2015年7月至8月,文章作者分别在雨天进行了降水取样,对降水中的pH、电导率、常见阴离子(F-、Cl~-、NO_3~(2-)、SO_4~(2-))及部分重金属(铅和镉)进行监测分析。选择有相关数据的珠江三角洲和石家庄、厦门等地的降水中污染物的情况进行对比。结果表明,顺德新城区降水中的p H和部分阴离子浓度优于珠江三角洲平均值,酸雨类型属于硫酸和硝酸混合型;其水体洁净程度略差于石家庄;铅和镉的浓度也高于厦门,甚至部分超出了人体能直接接触的安全范围。     

Metabolism of trideuterated iso-lignoceric acid in rats in Vivo and in human fibroblasts in culture

Saturated very long chain fatty acids (fatty acids with greater than 22 carbon atoms; VLCFA) accumulate in peroxisomal disorders, but there is little information on their turnover in patients. To determine the suitability of using stable isotope-labeled VLCFA in patients with these disorders, the metabolism of 22-methyl[23,23,23-²H₃]tricosanoic (iso-lignoceric) acid was studied in rats in vivo and in human skin fibroblasts in culture. The deuterated iso-VLCFA was degraded to the corresponding 16- and 18-carbon iso-fatty acids by rats in vivo and by normal human skin fibroblasts in culture, but there was little or no degradation in peroxisome-deficient (Zellweger’s syndrome) fibroblasts, indicating that its oxidation was peroxisomal. Neither the 14-, 20-, and 22-carbon iso-fatty acids nor the corresponding odd-chain metabolites could be detected. In the rat, the organ containing most of the iso-lignoceric acid, and its breakdown products, was the liver, whereas negligible amounts were detected in the brain, suggesting that little of the fatty acid crossed the blood-brain barrier. Our data indicate that VLCFA labeled with deuterium at the ω-position of the carbon chain are suitable derivatives for the in vivo investigation of patients with defects in peroxisomal β-oxidation because they are metabolized by the same pathways as the corresponding n-VLCFA. Moreover, as iso-VLCFA and their β-oxidation products are readily separated from the corresponding n-fatty acids by normal chromatographic procedures, the turnover of VLCFA can be more precisely measured. A preliminary report of part of this work (Reference 18) was presented at the 5th International Symposium on the Synthesis and Applications of Isotopes and Isotopically Labelled Compounds, Strasbourg, France, June 20–24, 1994.     

高效液相色谱法分析化妆品中微量成分的研究进展

综述了高效液相色谱法在化妆品中防腐剂、防晒剂中紫外线吸收剂以及性激素的检测等几个方面的应用;同时,介绍了分析所用的色谱柱、流动相、使用的检测手段以及样品的提取方法;最后针对目前存在的问题,提出了高效液相色谱用于化妆品中微量成分分析的研究方向和发展前景。     

Denitrification in shallow groundwater in a coastal agricultural area in Japan

In a coastal agricultural area in the central part of Japan (Shizuoka), we found decreasing nitrate concentration with depth in a shallow groundwater, where the depth to water table varied between 0.6 and 1.2 m below ground surface. High nitrate concentrations (5–29 mg N L^–1) were often observed in the upper layer (0–2 m) of the groundwater, but the concentration decreased to less than 1 mg N L^–1 in the deeper layer. Ammonium was scarcely detected, and the concentration of dissolved oxygen was usually low (< 1 mgO₂ L^–1) in the groundwater. Nitrate in the groundwater often had very heavy nitrogen stable isotope ratios (>20{}). There was a negative relationship between nitrogen stable isotope ratio of nitrate and its concentration. When nitrate was injected into the groundwater with acetylene and bromide (a conservative tracer), nitrate concentration decreased to 20% of the initial level within 5 days, accompanied by the increase in nitrite and nitrous oxide concentration and a little change in bromide concentration. These results indicate that microbial denitrification plays a potential role in the decrease of nitrate in shallow groundwater at the study site.     

我国硝酸工业生产技术新进展

系统叙述了我国硝酸工业2000-2007年生产现状及主要技术成果,尤其指出了国产"四合一"机组的成功投运,使我国硝酸国产化装置取得较大的进步,表现在吨酸的铂耗、氨耗和能耗等方面接近国外引进装置水平,同时介绍了国外双加压法硝酸生产技术的进展.我国已成为硝酸生产大国,仍需以先进的技术改造和发展我国硝酸工业,确保我国硝酸工业健康有序地发展,加快从硝酸生产大国向强国迈进的步伐.