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金属有机化合物的分析(Ⅵ)——极性与非极性二茂铁化合物的高效液相色谱研究 总被引:1,自引:0,他引:1
本文以国产YWG-C_(18)H_(37)(十八烷基键合微粒硅胶)为固定相,以不同比例的甲醇-水为流动相进行二茂铁化合物的反相高效液相色谱研究,分离了十一类共32种不同极性的二茂铁化合物,并探讨了它们在反相色谱中保留特性和分子结构的关系。 相似文献
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亲水作用色谱是采用极性固定相、高含量极性有机溶剂-水相缓冲液为流动相的一种分离技术,它能有效地保留反相色谱中保留弱或不保留的强极性碱性药物。本文综述了以未键合硅胶为固定相的亲水作用色谱分离碱性药物的机理、特点及其应用的最新进展。 相似文献
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采用原子层沉积法对十八烷基键合硅胶进行端基封尾.以六甲基二硅氮烷为封端试剂,在250 ℃下与键合硅胶样品反应6 h,制备了对碱性化合物具有高惰性的反相色谱填料.分别以吡啶/苯酚和萘/阿米替林为分子探针,考察了经原子层沉积法和传统液相有机溶剂法封尾处理的十八烷基键合硅胶的色谱性能,并与商品十八烷基硅胶Zorbax SB-C18和Kromasil C18进行对比.结果表明,原子层沉积法封尾的十八烷基硅胶对碱性化合物的分离特性明显优于传统液相法,其色谱性能已超过Zorbax SB-C18,与Kromasil C18相当.本方法无需有机溶剂,操作简便,反应耗时短,易于放大生产,封尾反应完全,应用前景良好. 相似文献
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以十二烷基键合氧化锆(C12-ZrO2)作为固定相,制备了填充毛细管电色谱(CEC)柱,较为系统地研究了流动相条件对电渗流的影响、填充CEC柱的稳定性、碱性与中性化合物的保留与流动相pH值和有机溶剂含量的关系。C12-ZrO2固定相填充CEC柱在pH3~11.7范围内具有极好的稳定性;利用磷酸盐与氧化锆表面之间较强的相互作用,能够有效解决传统硅胶键合烷基固定相在有机溶剂含量低的流动相条件下不稳定的问题;同时吸附磷酸盐的固定相表面使得在更宽的流动相pH值范围内CEC柱有足够的电渗流,进一步拓宽CEC的应用领域。 相似文献
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一种新型液相色谱屏蔽键合相的色谱性能 总被引:2,自引:0,他引:2
烷基硅胶键合固定相 ,特别是十八烷基键合固定相 ,是应用最广泛的反相色谱固定相 ,改变流动相组成 ,就可实现大多数有机化合物的分离分析 .但是 ,由于硅胶表面残留硅醇基的存在 ,分离某些极性化合物 ,特别是碱性有机化合物时使色谱峰变形拖尾 ,灵敏度下降 .采用封端技术也不能完全消除残留硅醇基的影响 .在分离碱性物质时大都采用缓冲溶液流动相 ,长期使用缓冲溶液将影响仪器和色谱柱的性能和寿命 .近年来 ,为了改善碱性化合物的分离 ,提出了空间保护相 [1] 和烷基酰胺屏蔽相 [2 ,3] .依据静电屏蔽原理 ,我们 [4 ]曾制备了十四烷基胺反相色… 相似文献
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以大黄酸为原料,γ-氨丙基三乙氧基硅烷(KH-550)为偶联剂,简便制备了一种新型羧基键合硅胶固定相(RBSP),并用红外光谱、热重分析及元素分析对其结构进行表征.考察了流动相中甲醇含量对键合固定相色谱性能的影响,并以含酸性、中性和碱性化合物的混合物为溶质,评价了RBSP的色谱性能.以甲醇-水为流动相,用C18柱作参比,研究了该键合硅胶作为HPLC固定相对两种大豆异黄酮化合物和几种生物碱基的分离,并对其色谱分离机理进行了初步探讨.实验结果表明,该固定相(RBSP)具有较好的反相色谱性能,同时由于键合相中含有酚羟基及酰胺基团,能为多种溶质提供作用位点,对极性化合物的分离具有明显优势,且分离速度快,可有效用于极性化合物的分离分析. 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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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. 相似文献