共查询到20条相似文献,搜索用时 140 毫秒
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7-氨基-3-乙烯基头孢烷酸(7-AVCA)是合成头孢类药物——头孢克肟和头孢地尼的关键中间体。对7-AVCA的不同合成方法进行了总结,指出以7-苯乙酰氨基-3-氯甲基-4-头孢烷酸对甲氧基苄酯(GCLE)为原料的合成路线中由于酶解法具有对环境友好、反应条件温和等诸多优点,有逐步取代化学法的趋势。 相似文献
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头孢菌素类抗生素是一类低毒、高效、抗菌谱广的药物,今天已经发展到了第四代并在临床上得到了广泛应用。其中7-苯乙酰胺-3-氯甲基头孢烯酸对甲氧基苄酯(GCLE)、7-氨基-3-乙酰基氧基头孢烷酸(7-ADCA)和7-氨基头孢烷酸(7-ACA)是合成头孢抗菌素类药物的三大主要母核或中间体。头孢菌类抗生素在β-内酰胺族抗生素中占有相当大的比重, 相似文献
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7-氨基-3-去乙酰氧基头孢烷酸(简称7-ADCA)是一种重要的头孢类抗菌素半合成的中间体,在医药工业上用于合成头孢氨苄、头孢拉定、头孢克罗、头孢他美酯和头孢羟氨苄等药物,这些药物都是市场用量较大的抗生素。 相似文献
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以7-苯乙酰氨基-3-氯甲基头孢烷烯酸对甲氧基苄酯(简称GCLE)取代7-ACA,直接和三嗪环反应合成头孢曲松中间体7-苯乙酰氨基-3-三嗪环甲基头孢-4-羧酸对甲氧苄酯,通过高效液相色谱仪对反应过程进行监测。研究了该反应的动力学,确定反应为SN2历程,通过测定25℃、35℃下在不同溶剂中反应的速率常数,得出其亲核取代反应活性顺序为:乙腈〉四氢呋喃。 相似文献
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采用亚胺基氯化物法,制备头孢克肟的中间体7-氨基-3-乙烯基-头孢烷酸对甲氧基苄酯盐酸盐。7-苯乙酰胺基-3-氯甲基-头孢烯酸对甲氧基苄酯经3位Wittig反应后用亚胺基氯化物法脱去7位侧链,得目的产物。反应条件温和,周期缩短,总收率70%。 相似文献
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多沙唑嗪通常由中间体BCP和ACQ合成,为考察产品质量,有必要建立多沙唑嗪及其中间体的测定方法。该文建立并优化了反相高效液相色谱法(RP-HPLC)同时测定多沙唑嗪及其中间体。结果表明,以C18柱(4.6mm×250 mm)为色谱柱,流动相组成V(CH3OH)∶V[c(KH2PO4)=0.02 mol/L,pH=3.0]=70∶30,流速0.6 mL/min,检测波长246 nm,多沙唑嗪与BCP、ACQ可达到基线分离,分离度大于2.0。各物质在1~20 mg/L内的色谱峰面积与质量浓度之间线性关系良好(r>0.999),该方法的准确度(回收率>99%)和精密度(RSD<4%)高,操作简便快速,可望用于多沙唑嗪产品质量研究和控制。 相似文献
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含氟农药是当前国内外广受重视的新型农药。乙氧氟草醚(2-氯-4-三氟甲基苯基3’-乙氧基-4’-硝基苯基醚,Oxyfluorfen)就是一种高效、低残留、选择性好,水、旱田兼用的广谱性除草剂,该产品的研制被国家列入科研攻关项目。在实施工业化生产中,为了满足工程设计和能量计算等要求,需要提供与乙氧氟草醚相关的若干重要中间体的物性数据, 相似文献
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<正>含氟农药是当前国内外广受重视的新型农药。乙氧氟草醚(2-氯-4-三氟甲基苯基3’-乙氧基-4’-硝基苯基醚,Oxyfluorfen)就是一种高效、低残留、选择性好,水、旱田兼用的广谱性除草剂,该产品的研制被国家列入科研攻关项目。在实施工业化生产中,为了满足工程设计和能量计算等要求,需要提供与乙氧氟草醚相关的若干重要中间体的物性数据, 相似文献
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7-对甲苯硫亚氨基-3-(1-甲基-1H-四唑-5-硫甲基)-3-头孢烯-4-羧基酸二苯甲酯(7-DTMC)是合成甲氧头孢菌素关键中间体7β-氨基-7α-甲氧基-3-(1-甲基-1H-四唑-5-硫甲基)-3-头孢烯-4-羧酸二苯甲酯(7-MAC)的重要中间体。采用7β-氨基-3-(1-甲基-1H-四唑-5-硫甲基)-3-头孢烯-4-羧酸二苯酯(7-DAMC)为原料,以对甲基苯硫氯(TSC)为氨基保护试剂,二氯甲烷为溶剂,1,2-环氧丙烷为催化剂和4分子筛为脱水剂剂反应制备得到7-DTMC。本文主要探讨了反应温度、反应时间、物料配比、催化剂用量等因素对反应的影响,并通过二次回归建立了数学模型,确定了合成7-DTMC的最佳工艺条件。在此基础上合成的产品收率89.71%,HPLC纯度99.34%。产品结构经1H-NMR和FT-IR表征确认。 相似文献
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Maria Stylidi Dimitris I. Kondarides Xenophon E. Verykios 《Applied catalysis. B, Environmental》2003,40(4):271-286
The photocatalytic degradation of aqueous solutions of Acid Orange 7 in TiO2 suspensions has been investigated with the use of a solar light simulating source. The photoreaction was followed by monitoring the degradation of the dye and the formation of intermediates and final products, as functions of time of irradiation, both in solution and on the photocatalyst surface. It has been found that the dye adsorbs on TiO2 and undergoes a series of oxidation steps, which lead to decolorization and formation of a number of intermediates, mainly aromatic and aliphatic acids. These molecules are further oxidized toward compounds of progressively lower molecular weight and, eventually, to CO2 and inorganic ions, such as sulfate, nitrate and ammonium ions. A TiO2-mediated photodegradation mechanism for Acid Orange 7 is proposed on the basis of quantitative and qualitative detection of intermediate compounds. 相似文献
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Wentrup C 《Accounts of chemical research》2011,44(6):393-404
Rearrangements of aromatic and heteroaromatic nitrenes and carbenes can be initiated with either heat or light. The thermal reaction is typically induced by flash vacuum thermolysis, with isolation of the products at low temperatures. Photochemical experiments are conducted either under matrix isolation conditions or in solution at ambient temperature. These rearrangements are usually initiated by ring expansion of the nitrene or carbene to a seven-membered ring ketenimine, carbodiimide, or allene (that is, a cycloheptatetraene or an azacycloheptatetraene when a nitrogen is involved). Over the last few years, we have found that two types of ring opening take place as well. Type I is an ylidic ring opening that yields nitrile ylides or diazo compounds as transient intermediates. Type II ring opening produces either dienylnitrenes (for example, from 2-pyridylnitrenes) or 1,7-(1,5)-diradicals (such as those formed from 2-quinoxalinylnitrenes), depending on which of these species is better stabilized by resonance. In this Account, we describe our achievements in elucidating the nature of the ring-opened species and unraveling the connections between the various reactive intermediates. Both of these ring-opening reactions are found, at least in some cases, to dominate the subsequent chemistry. Examples include the formation of ring-opened ketenimines and carbodiimides, as well as the ring contraction reactions that form five-membered ring nitriles (such as 2- and 3-cyanopyrroles from pyridylnitrenes, N-cyanoimidazoles from 2-pyrazinyl and 4-pyrimidinylnitrenes, N-cyanopyrazoles from 2-pyrimidinylnitrenes and 3-pyridazinylnitrenes, and so forth). The mechanisms of formation of the open-chain and ring-contraction products were unknown at the onset of this study. In the course of our investigation, several reactions with three or more consecutive reactive intermediates have been unraveled, such as nitrene, seven-membered cyclic carbodiimide, and open-chain nitrile ylide. It has been possible in some cases to observe them all and determine their interrelationships by means of a combination of matrix-isolation spectroscopy, photochemistry, flash vacuum thermolysis, and computational chemistry. These studies have led to a deeper understanding of the nature of reactive intermediates and chemical reactivity. Moreover, the results indicate new directions for further exploration: ring-opening reactions of carbenes, nitrenes, and cyclic cumulenes can be expected in many other systems. 相似文献