溴甲酚绿与甲砜霉素的显色反应及应用

在pH 4.0～5.3的条件下,甲砜霉素与溴甲酚绿反应生成具有1个正吸收峰和2个几乎相等的负吸收峰的离子缔合物。最大正吸收波长位于610 nm,2个负吸收波长分别位于652 nm和574 nm,表观摩尔吸光系数分别为2.16×104 L.mol-1.cm-1(正吸收),1.36×104 L.mol-1.cm-1(652 nm负吸收)和1.32×104 L.mol-1.cm-1(574 nm负吸收),线性范围均为0～5.3 mg/L。甲砜霉素在一定浓度范围内遵从朗伯比尔定律,由此建立了测定甲砜霉素的正吸收、负吸收及双波长叠加吸收光谱法。方法已用于人体尿液、血液及市售药物中甲砜霉素含量的测定。     

维多利亚蓝B-双波长分光光度法测定垃圾渗滤液中十二烷基磺酸钠

在pH 7.3的B-R缓冲溶液中,阴离子表面活性剂十二烷基磺酸钠(SDS)与维多利亚蓝B(VBB)以物质的量比2:1反应生成具有正吸收和负吸收的蓝色离子缔合物,最大正吸收波长为690 nm,最大负吸收波长为615 nm,线性范围分别为0.2～8.2 mg·L-1(正吸收)和0.2～6.8 mg·L-1(负吸收),表观摩尔吸光率为3.48×104L·mol-1·cm-1(正吸收)和2.14×104L·mol-1·cm-1(负吸收),采用双波长叠加测定,灵敏度可达5.60×104L·mol-1·cm-1,据此建立了测定SDS含量的双波长分光光度法.探讨了适宜的反应条件及垃圾渗滤液的预处理方法.该法用于垃圾渗滤液中SDS含量的测定,回收率在98.5 0A～101.0H之间,测定值的相对标准偏差(n=5)在0.8%～1.5%之间.     

甲基紫探针分光光度法测定利福平

在pH 7.3的Tris-HCl缓冲溶液中,甲基紫与利福平反应生成具有正吸收峰和负吸收峰的紫色络合物。其最大正吸收波长位于500 nm,最大和次大负吸收波长分别位于540 nm和605 nm,利福平的质量浓度在0.2～0.82 mg·L-1(正吸收)和0.0～0.82 mg·L-1(负吸收)以内与吸光度A呈线性关系,服从比尔定律,表观摩尔吸光系数分别为8.90×104(500 nm)、4.41×105(540 nm)和3.04×105(605 nm)L·mol-1·cm-1,该法用于市售利福平药物中利福平的测定结果满意。     

溴甲酚绿探针-分光光度法测定大观霉素

在pH 5的Tris-盐酸缓冲介质中,溴甲酚绿与大观霉素反应生成具有正、负吸收峰的离子缔合物,最大正吸收波长位于580nm处,最大负吸收波长位于449nm处,表观摩尔吸光率(ε)分别为3.41×104,2.86×104L·mol-1·cm-1,大观霉素在0.6~9.2mg·L-1(正吸收)和0.6~11.1mg·L-1(负吸收)范围内遵从比尔定律。当改用双波长法并用双吸收峰法检测时,灵敏度可提高到6.26×104L·mol-1·cm-1。方法用于市售大观霉素药物中大观霉素含量的测定,测定值与标示量相符。     

利血平与玫瑰精B的高灵敏显色反应及分析应用

研究了利血平与玫瑰精B的显色反应,建立了测定利血平的高灵敏分光光度法。在酸性条件下,利血平的水解产物和玫瑰精B形成具有正、负吸收峰的红色离子缔合物,最大正吸收波长位于490 nm,最大负吸收波长位于520 nm,表观摩尔吸光系数(ε)分别为1.20×105L.mol-1.cm-1(正吸收)和1.83×105L.mol-1.cm-1(负吸收),利血平在0～5.0μg/mL范围内遵从比尔定律。若采用正、负峰叠加测定,灵敏度可达3.00×105L.mol-1.cm-1。探讨了适宜的反应条件、主要分析特性及方法的精密度和可靠性。该法可用于市售利血平注射液中利血平含量的测定。     

伊文思蓝光度法测定硫酸阿米卡星的含量

在pH 2.5～6.2的条件下,硫酸阿米卡星(AMK)与伊文思蓝(EB)反应,生成蓝色离子缔合物,最大吸收波长和负吸收波长分别位于678 nm和606 nm,表观摩尔吸光系数(ε)分别为3.02×104L·mol-1·cm-1和4.91×104L·mol-1·cm-1.当用双波长叠加法测定时,ε值可提高到7.95×104L·mol-1·cm-1.该法用于药物中硫酸阿米卡星含量的测定,结果满意.     

镧-甲基蓝光度法测定硫酸卡那霉素及硫酸新霉素

镧(Ⅲ)-甲基蓝(MB)在酸性条件下与硫酸卡那霉素(KANA)及硫酸新霉素(NEO)反应生成蓝色离子缔合物,两者的最大正吸收波长均位于682 nm,表观摩尔吸光系数为1.71×104L.mol-1.cm-1(KANA)和1.21×104L.mol-1.cm-1(NEO);最大负吸收波长位于620 nm(KANA)和616 nm(NEO),表观摩尔吸光系数为9.57×104L.mol-1.cm-1(KANA)和8.68×104L.mol-1.cm-1(NEO);用双波长法测定时,摩尔吸光系数可达1.10×105L.mol-1.cm-1(KANA)和1.00×105L.mol-1.cm-1(NEO)。方法用于市售药物中硫酸卡那霉素及硫酸新霉素含量的测定,结果与标示值相符,回收率在99.8%~100.5%之间。     

氯霉素与氯酚红的吸收光谱及应用

建立了测定氯霉素含量的负吸收光谱法.在弱碱性条件下,氯酚红与氯霉素反应生成具有明显负吸收峰的紫色离子缔合物.最大负吸收波长位于550 nm,表观摩尔吸光系数(ε)为1.01×104L·mol-1·cm-1,氯霉素的质量浓度在0.32 ～6.5 mg/L范围内服从比尔定律.探讨了适宜的反应条件、方法的精密度及可靠性.用于...     

铕-苯胺蓝-阿米卡星的显色反应及其应用

在微酸性条件下,铕-苯胺蓝(ABWS)与阿米卡星(AMK)反应,生成三元蓝色离子缔合物。其最大正吸收波长位于676 nm,最大负吸收波长位于606 nm,表观摩尔吸光系数分别为4.59×104和9.25×104L.mol-1.cm-1;用双波长法测定时,摩尔吸光系数可达1.38×105L.mol-1.cm-1;AMK浓度在0~1.5 mol.L-1(正吸收)和0~1.6 mol.L-1(负吸收)之间遵守比耳定律。由此建立了测定阿米卡星的单波长及双波长分光光度法。方法用于市售药物及人体尿液中阿米卡星含量的测定,所得测定值的RSD均小于1.5%,回收率试验的结果在99.7%~100.3%之间。     

酸性铬蓝K分光光度法测定氯霉素

在pH 9.66的Tris-盐酸缓冲溶液中,氯霉素与酸性铬蓝K反应形成具有正吸收和负吸收的离子缔合物,最大正吸收波长为498nm,最大负吸收波长为594nm,线性范围分别在3.2mg.L-1(正吸收)、3.9 mg.L-1(负吸收)以内,表观摩尔吸光率分别为5.93×104L.mol-1.cm-1(正吸收)、2.32×105L.mol-1.cm-1(负吸收),据此建立了测定氯霉素含量的分光光度法。方法用于氯霉素注射液及滴眼液中氯霉素的测定,回收率在98.9%～101.2%之间,相对标准偏差(n=6)在0.8%～1.2%之间。     

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.     

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.