双波长光度法测定阿米卡星的研究

在酸性条件下,水溶苯胺蓝(ANB)与硫酸阿米卡星(AMK)反应,生成蓝色离子缔合物,其最大正吸收波长位于682nm,最大负吸收波长位于602nm,正负峰吸光度绝对值之和与AMK的浓度线性相关,AMK的浓度在0～1.8×10-5mol·L-1的范围内遵从朗伯比耳定律,表观摩尔吸光系数为9.50×104L·mol-1·cm-1,由此建立了测定阿米卡星的双波长光度法。方法用于市售药物及人体尿液中阿米卡星含量的测定,结果满意。     

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。     

夜蓝与阴离子表面活性剂在水溶液中显色反应——吸光光度法测定环境水样中阴离子表面活性剂

在聚乙烯醇存在的1.8mol/L磷酸溶液中,夜蓝与阴离子表面活性剂形成离子缔合物。溶液由绿色变为蓝色,可用于水相直接光度测定阴离子表面活性剂。最大吸收波长555nm,摩尔吸光系数分别为5.72×10~4L·mol~(-1)·cm~(-1)(十二烷基苯磺酸钠),5.77×10~4 L·mol~(-1)·cm~(-1)(十二烷基硫酸钠),4.36×10~4 L·mol~(-1)·cm~(-1)(十二烷基磺酸钠)。方法简便、快速,具有良好的选择性。可用于河水和生活废水中10~(-6)—10~(-7)mol/L阴离子表面活性剂的测定。     

甲基蓝与庆大霉素、妥布霉素的褪色反应及其应用

在酸性条件下,硫酸庆大霉素(GEN)、硫酸妥布霉素(TOB)与甲基蓝(MB)反应,生成离子缔合物,使甲基蓝褪色,其最大褪色波长位于606nm(GEN)和610nm(TOB),表观摩尔吸光系数(ε)为1.80×104(GEN)和2.93×104(TOB)L·mol-1·cm-1;庆大霉素、妥布霉素浓度在0～1 2×10-5mol·L-1范围内遵从比耳定律。该法用于市售药物及人体尿液中庆大霉素及妥布霉素含量的测定,结果满意。     

亚甲基蓝光度法测定西地那非的含量

在pH3.0～6.0的条件下,亚甲基蓝(MB)与西地那非(SD)反应,生成蓝色离子缔合物,最大吸收波长位于600nm,SD浓度在0～1.6×10-5mol/L范围服从比耳定律,由此建立了测定西地那非含量的分光光度法。缔合物的表观摩尔吸光系数(ε)为3.0×104L·mol-1·cm-1。该方法用于市售药物中西地那非含量的测定,结果满意。     

槲皮素-钼(Ⅵ)-CTMAB荧光体系的研究及应用

研究了槲皮素 钼(Ⅵ) CTMAB荧光体系的形成条件,并建立了测定槲皮素的荧光光度法。在pH 2.5~3.5的酸度条件下,形成槲皮素∶钼(Ⅵ)∶CTMAB=2∶2∶1 的黄色荧光络合物,激发波长为404.9 nm,发射波长为 472.2 nm,槲皮素浓度在 2.0×10-6 ~1.0×10-5 mol·L-1范围内与荧光强度呈线性关系,检出限为3.4×10-8mol·L-1,所拟方法用于测定中药槐米中的槲皮素,结果满意。     

偶氮蓝分光光度法测定硫酸卡那霉素

在pH 4.10的B-R缓冲溶液中,偶氮蓝与硫酸卡那霉素相互作用生成离子缔合物导致偶氮蓝色泽减褪,或换言之,当在偶氮蓝溶液中加入硫酸卡那霉素后,在偶氮蓝的吸收峰552 nm波长处吸光度降低,吸光度差值与硫酸卡那霉素浓度成正比,最佳条件下,硫酸卡那霉素的质量浓度在0.1～4.0 mg·L-1范围内遵守比耳定律,表观摩尔吸光率ε=7.3×104L·mol-1·cm-1,检出限(3σ)为7.6×10-2mg·L-1.将方法应用于硫酸卡那霉素注射液试样中卡那霉素的测定,测定结果的RSD(n=7)值为1.1%,按标准加入法测得的平均回收率为96.5%.     

土壤中水溶性NH4^＋的吸光光度测定

推荐了一个测定土壤中水溶性NH_4~+的灵敏的吸光光度方法。方法基于NH_4~+与水杨酸在次氯酸钠和亚硝基铁氰化钠存在下形成一种有色配合物的反应。最大吸收波长为698nm,体系中NH_4~+浓度在0～1μg·ml~(-1)范围内符合比耳定律,测得摩尔吸光系数ε=1.4×10~4,Sandell灵敏度为1.0×10~(-3)μg·cm~(-2)。可见方法灵敏度高,因此可应用于土壤中痕量NH_4~+的直接吸光光度法测定。     

钍(Ⅳ)与偶氮溴膦-mB和溴化十四烷基吡啶在乙醇-水溶液中的显色反应及其分析应用

在pH1～2的酸性介质中,钍(Ⅳ)与偶氮溴膦-mB(BPAmB)形成最大吸收波长(λ_(max)位于686nm的蓝色络合物,摩尔吸光系数(ε)为8.27×10~4L·mol~(-1)·cm~(-1).在有少量乙醇存在的0.5～1.0 mol/L盐酸溶液中,钍(Ⅳ)能与BPAmB和溴化十四烷基吡啶形成更灵敏的三元络合物,最大吸收位于695nm,具有更大的对比度(△λ=135nm)和更高的灵敏度.ε值达1.41×10~5L·mol~(-1)·cm~(-1),是目前光度法测定钍(Ⅳ)灵敏度最高的显色反应之一,Th(Ⅳ)的浓度在0～800μg/L范围内遵守比尔定律.方法具有良好的选择性,此法用于岩矿中微量钍的测定,结果满意.     

新显色剂四-(4-氯-3-磺酸苯基)卟啉吸光光度法测定微量铜

四-(4-氯-3-磺酸苯基)卟啉是一种新显色剂,在微酸性(pH 4.9～5.3)介质中,有混合表面活性剂CPC-OP存在下与Cu(Ⅱ)形成稳定的配合物,最大吸收波长在420nm处,铜量在0.5～4.5pg/25ml范围内符合比耳定律,求算表观摩尔吸光系数ε_(420)=2.96×10~5L·mol~(-1)·cm~(-1),用双峰双波长光度法测定,相应的表观摩尔吸光系数ε′_(420-445)=5.71×10~5L·mol~(-1)·cm~(-1)。用拟定的方法进行样品中微量铜的测定,结果满意。     

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%.     

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.     

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.