原子吸收光谱法间接测定碘解磷定

研究了原子吸收光谱法间接测定碘解磷定。在pH5．0溶液中,当四苯硼钠过量时可完全沉淀碘解磷定,在滤液中加入过量的KCl沉淀剩余的四苯硼钠．再测定滤液中的过量的钾,可以计算得到碘解磷定的量。方法的回收率在98％～103％之间．相对标准偏差为1．8％。     

间接原子吸收光谱法测定甲基硫酸新斯的明

建立了原子吸收光谱法间接测定甲基硫酸新斯的明的方法。在pH5．0溶液中，当四苯硼钠过量时可完全沉淀甲基硫酸新斯的明，在滤液中加入过量的KCl沉淀剩余的四苯硼钠，再测定滤液中的过量的钾，可以计算得到甲基硫酸新斯的明的质量分数。方法回收率在97％～103％之间，相对标准偏差为1．5％。     

间接原子发射光谱法测定氢溴酸山莨菪碱

研究了电感耦合等离子体-原子发射光谱法间接测定氢溴酸山莨菪碱。在pH5．0溶液中过量四苯硼钠可使氢溴酸山莨菪碱沉淀完全，加入氯化钾沉淀滤液中剩余的四苯硼钠，测定滤液中过量的钾，可以计算得到氢溴酸山莨菪碱的含量。方法简单快速，回收率在97％～102％之间，相对标准偏差为1．3％。     

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。     

四苯硼钠沉淀-ICP 发射光谱法间接测定药物片剂中扑尔敏含量

研究了等离子体发射光谱法间接测定药物片剂中扑尔敏的含量。选择了沉淀条件及ＩＣＰ－ＡＥＳ测定的最佳条件。在ＰＨ２－４．５范围内,当四苯硼钠过量时可完全沉淀扑尔敏。硝酸铝可以使沉淀导速如凝而易于过滤,测定滤液中的四苯硼钠计算得扑尔敏的含量。方法的相对标准偏差为２．２％回收率为９９％－１０２％,已用于实际样品的分析。     

甲基硫酸新斯的明的ICP-AES测定

研究了电感耦合等离子体原子发射光谱法间接测定甲基硫酸新斯的明，在溶液pH为5.0，四苯硼钠过量时可完全沉淀甲基硫酸新斯的明，测定滤液中的四苯硼钠可以计算得到甲基硫酸新斯的明的含量；方法简单快速，回收率在95％-101％之间，相对标准偏差为1.8％。     

示波滴定法测定铝合金中铜的含量

研究了铝合金中铜含量的示波滴定法。在酸性溶液中抗坏血酸将铜（Ⅱ）还原为铜（Ⅰ），用过量四苯硼钠沉淀铜（Ⅰ），过量的四苯硼钠用氯化四乙基铵标准溶液返滴定，以四苯硼钠切口消失为终点，计算出铜含量。方法终点变化敏锐，不外加指示剂，与标准分析方法相比较，操作简便、快速，所用分析试剂无毒，测定结果的RSD小于0．19％，标准加入回收率为98．7％～102．0％。     

四苯硼钠法测定吡哌酸含量

介绍一种测定吡哌酸含量的有效方法。在ｐＨ＝３．６的ＨＡｃ－ＮａＡｃ缓冲溶液中,吡哌酸与四苯硼钠可形成１：１的定量沉淀,待沉淀反应完全后,以溴酚蓝为指示剂,用烃铵盐标准溶液回滴过量的四苯硼钠,方法简便、快速,应用于吡哌酸原料药品测定,其回收率为９９．４４％～１００．０９％,最大相对误差〈±０．６％,与药典法测得的结果基本一致。     

交流示波极谱滴定法测定氧氟沙星的研究

报道了用交流示波极谱滴定法测定氧氟沙星（ＯＦＸ）含量。用ｐＨ４．０的ＨＡｃ－ＮａＡｃ缓冲溶液溶解样品，加入过量的四苯硼钠（Ｎａ－ＴＰＢ）使药样沉淀完全１，过滤后滤液用硫酸亚铊标准溶液进行返滴定，由示波极谱图［ｄＥ／ｄｔ＝ｆ（Ｅ）］上ＴＰＢ切口的消失指示滴定终点。应用于片剂和注射剂测定，平均加标回收率为１００．０２％，相对标准偏差≤０．１７％。     

电感耦合等离子体原子发射光谱法间接测定盐酸苯海索

研究了等离子发射光谱法间接测定片剂中盐酸苯海索含量的方法。详细讨论了ICP AES测定硼的“记忆效应”及最佳测定条件。实验表明在pH 2 .0～ 6 .0范围内 ,当四苯硼钠过量时可完全沉淀盐酸苯海索 ,硝酸铝可以使沉淀迅速絮凝而易于过滤 ,测定滤液中的四苯硼钠可以计算得到盐酸苯海索的含量。该法简单快速 ,相对标准偏差为 2 1%。实验测得盐酸苯海索 四苯硼沉淀的溶度积Ksp在 2 0℃时为8 84× 10 -12     

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.     

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.     

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.