测定季铵盐类药物含量的示波极谱-四苯硼钠滴定法

以四苯硼钠 (Na_TPB)为沉淀剂、四乙基氯化铵为滴定剂 ,采用示波极谱滴定法测定氯化琥珀胆碱、溴化新斯的明、碘解磷定3种氢卤酸季铵盐类药物制剂的含量。样品在 pH5.0的NaAc -HAc缓冲溶液中加入过量的四苯硼钠,使试样沉淀完全,过滤后滤液在碱性条件下用四乙基氯化铵标准溶液进行反滴定,由示波极谱图上TPB切口的消失指示滴定终点。该法具有简便、准确、快速的优点,测定结果令人满意。     

电滴定分析的新方法

利用示波极谱图上切口的出现或消失来指示滴定终点的示波极谱滴定法具有终点直观、操作简便和抗干扰能力强等优点。但该法要求试剂(滴定剂、被滴物或指示剂)能在示波极谱图上产生敏锐切口才能应用。     

示波极谱滴定法测定生物碱氢溴酸盐类药物

以ＡｇＮＯ３作滴定剂，ＫＮＯ３和磺基水杨酸为极谱底液，采用交流示波极谱滴定法测定氢溴酸山莨菪碱、氢溴酸东莨菪碱、氢溴酸加兰他敏三种生物碱氢溴酸盐类药物的含量。该法到目前为止未见报道，具有快速、准确、终点直观的特点。     

示波极谱-四苯硼钠法的研究与应用

生物碱、季铵盐是重要的两大类药物。钾、铊、银、铜、铷、铯都是有重要用途的金属元素。其分析测试方法已报道的有重量法、萃取 -光度法、非水滴定法。本文依据四苯硼钠 ( Na TPB)与生物碱类药物、季铵盐类药物及 K+、Tl+、Ag+、Cu+、Rb+、Cs+一价金属离子在一定条件下均能发生定量地沉淀反应 ,又由于 Na TPB是示波活性物质 ,在交流示波极谱图上有敏锐的切口 ,可用 Na TPB切口的出现或消失指示滴定的终点 ,据此建立了示波极谱 -四苯硼钠测定法。方法具有准、快、简、省的特点     

交流示波极谱滴定法测定度米芬含量

度米芬(Domiphen Bromide)是一种阳离子表面活性杀菌剂,其结构式为:测定方法有碘酸钾法、铁氰化钾法、四苯硼钠双相滴定法等。前两种方法操作繁琐,双相滴定法近终点时必须剧烈振摇,终点不易观察,且甩较大量氯仿既不经济又对人体有害。交流示波极谱四苯硼钠沉淀滴定法,可用于测定含氮有机药物。本文研究了交流示波极谱滴定法测定度米芬含量,方法准确,简单易行,终点灵敏直观。     

交流示波极谱法中电流—电位曲线的研究——Ⅲ.电流-电位曲线示波极谱络合滴定法

利用交流示波极谱法中i_f-E曲线来指示滴定终点的容量分析方法,叫做i_f-E曲线示波极谱滴定法。本文研究i_f-E曲线示波极谱络合滴定法。     

交流示波极谱滴定法

用交流示波极谱曲线(dE/dt)=f(E)上切口的出现或消失来指示滴定终点的容量分析方法称为交流示波极谱滴定法,简称示波极谱滴定。     

示波电位滴定法测定含硫药物

示波电位滴定法是近几年发展起来的一种最简单的电滴定法,它不需要示波极谱的切口,省去示波极谱的外接线路,只需将两支指示电极直接连于示波器的输入端即可,使设备更简单,操作更方便,便于掌握和推广.示波电位滴定法可用于酸碱、氧化还原、络合及沉淀滴定中,终点指示灵敏、直观,且不受溶液的颜色和浑浊现象的干扰.在沉淀滴定中,目前应用较多的是测定含C~-、Br~-的试样.对含硫试样的分析应用很少.曾有人研究SO_4~(2-)的测定,但由于存在生成硫     

三乙基四胺六乙酸交流示波极谱滴定法研究

本文提出了三乙基四胺六乙酸(TTHA)交流示波极谱滴定法,该法快速、准确、终点直观,用此法测定了多种金属离子,结果符合容量分析要求。     

示波极谱滴定法测定显影液中米吐尔含量

1引言米吐尔为对一甲氨基苯酚硫酸盐,它是黑白显影液中的主显影剂。显影液中米吐尔的测定通常采用分光光度法和林量法,电分析方法目前尚未见报道。光度法需要绘制曲线,较为费时;林量法则由于苹取分离样品时,乙酸乙酯和水相存在微量互溶,以及分层略有混溶,米吐尔的分析结果容易偏高,而形成系统误差。本文利用四本硼钠（NaTPB）与米吐尔在酸性条件下可1＋l生成沉淀,以四乙基氯化控为淄定剂,采用交流示波极谱满定法返滴过量Na．TPB,由示波极谱图上TPB切口消失指示滴定终点。本法操作简便快速,终点直观敏锐,应用于fi72和fr76…     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

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%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

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.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

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.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

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.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

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%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

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.