共查询到20条相似文献,搜索用时 46 毫秒
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采用自组装膜制备技术和超细亚微粒级吸附剂研制高效活性碳多孔层毛细管色谱柱(PLOT),选用K3PO4、K2HPO4和KH2PO4三种不同的磷酸盐对色谱柱进行改性脱活,考察了脱活盐浓度对色谱柱保留行为的影响程度,并采用研制的高效活性碳PLOT毛细管色谱柱对惰性气体和低碳烃(H2、Air、CO、CO2和C1-C4烃)进行了分离分析,结果表明:在高效活性碳PLOT毛细管色谱柱制备工艺中,活性碳吸附剂的最佳粒度为0.5-0.7μm之间;磷酸盐脱活剂的最佳浓度为1.5%,老化时间为250℃;所研制的高效活性碳PLOT毛细管色谱柱对惰性气体和低碳烃具有较好的分离度。 相似文献
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PLOT柱是用于永久性气体,低碳烃和挥发性化合物色谱分析的最有效的工具,经常用于替代经典填充柱,对多孔层开管毛细管柱(PLOT)吸附色谱的分离机理、PLOT柱制备方法和各类吸附剂的色谱特性及其特定应用进行了综述。 相似文献
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采用全新的两步原位合成法,制备高效一体化U型多孔层聚合物颗粒PLOT Pora-U毛细管色谱柱。先将带有双活性反应基团的γ-三甲氧基硅丙基异丁烯酸酯中的CH3—O—Si—基团与石英毛细管内壁表面的Si—OH反应,在石英毛细管内壁键合上带有活性基团的中间有机层,再原位合成多孔聚合物。该色谱柱具有良好的惰性和较强的分离能力。与一般的商品化PLOT-U色谱柱相比,热稳定性和机械强度有明显的改善和提高,色谱柱最高使用温度提高了20 ℃,达到210 ℃,对强极性物质、强活性化合物、永久性气体以及低碳化合物有较好的分 相似文献
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采用静态法涂柱以对甲苯磺酸二甲铵做为固定相制备了石英毛细管气相色谱柱(柱尺寸30m×0.5mmi.d,液膜厚度为0.7μm,固定液浓度9.94%W/V),并考察了它们的柱性能及不经衍生直接进样对有机羧酸的分离。实验表明,此种色谱固定相的柱流失温度可达225℃,平均McReynolds常数为304,理论塔板数每米2040块;对C2-C8的一元酸、C12-C16的高碳数酸及苯甲酸与山梨酸等芳香酸具有较好的分离能力并对C2-C8的一元酸进行定量分析(n=1 0),浓度从0.8807%~3.8084%,相对标准偏差在1.22%~4.20%之间。 相似文献
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采用全新的两步原位合成法,先通过将带有双活性反应基团γ—三甲氧基硅丙基异丁烯酸酯的CH3-O-Si-基团与石英毛细管内壁表面的Si-0H反应,在石英毛细管内壁键合上带有活性基团的中间有机层,再原位合成多孔聚合物,制成高效一体化Q型聚合物颗粒多孔层开管柱(PLOT)Pora-Q毛细管色谱柱;该色谱柱具有良好的惰性、较强的分离能力;与一般的商品化PLOT-Q色谱柱相比,热稳定性和机械强度有明显的改善和提高,最高使用温度提高了50℃达到300℃,扩展了该种色谱柱的应用范围。 相似文献
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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%. 相似文献
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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. 相似文献
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Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives. 相似文献
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The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion. 相似文献
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A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL. 相似文献
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Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
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. 相似文献
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A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions. 相似文献
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N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%). 相似文献
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Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones. 相似文献
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In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates. 相似文献