分光光度法测定亚甲基蓝溶液浓度线上实验设计

基于朗伯-比尔定律与互补色原理,利用QQ截图读取色块RGB三原色组成的功能,获得不同亚甲基蓝浓度色阶对应的红色和绿色信号,设计了亚甲基蓝测定的简易紫外-可见分光光度法实验方案。该方案包括标准色阶制作、颜色信号读取、标准曲线绘制,以及待测样品测试等。通过学生实验,获得了满意的可靠性。该实验方案尤其适用于线上教学或缺少分光光度计的线下教学。     

测定鱼中痕量硒的横向石墨炉原子吸收分光光度法

应用加拿大Aurora -1000型横向石墨炉原子吸收分光光度计测定鱼中痕量硒,优化了样品消化条件和待测元素的各项测定参数 ,并对横向石墨炉和纵向石墨炉在同等条件下测定硒作了较为详尽的比较。用该法对实际样品进行了测定,获得满意结果。     

简易双波长分光光度法装置研究

在分析工作中经常遇到浑浊试样,以及共存组分或显色剂的吸收光谱与被测组分的光谱部分重叠等情况。应用双波长分光光度计进行测定时,可以将这些干扰背景一并扣除,以简化测定手续、减少测定误差,扩大分光光度法的应用范围。由于双波长分光光度计价格昂贵,目     

程控电热蒸发动态分子吸收分光光度法的研究

本文报道的是利用原子吸收分光光度计石墨炉程序升温手段,使待测成份及共存组份以“分子云”形式分别在不同温度阶段蒸发,进行分离及动态分子吸收测量的一种技术。     

测定两干扰组分体系的新的吸光度图解法——定组分比推论法的研究

吸光光度法是广泛应用的一种方法,但在待测溶液中如果存在严重干扰的元素,方法将失效。本文试图从理论上研究出一种新的图解法.提出了测定两干扰组分体系的吸光度图解法--定组分比推论法。应用该法使用通常的分光光度计,不经分离或掩蔽,能在一种严重干扰元素存在下顺利地测定欲测元素的含量。本文从理论上研究了定组分比推论法的原理,并通过实验给以验证。它具有一定的普遍性,运用这种推理的方法,有可能扩大到其他领域。由于方法原理简单、无需特殊的仪器,故易于推广应用。     

测定诺氟沙星胶囊的新方法

诺氟沙星(Norfloxacinium)是近几年合成的新抗菌素(图1)。具有抗菌谱广,疗效好,毒性低等优点。目前已广泛应用于临床。中国药典1990年版中对诺氟沙星胶囊的含量测定采用非水滴定法。本文改进了此法,采用紫外分光光度法测定该品种含量。实验表明该法简便、快速、重现性也较好。仪器与试药仪器:日本岛津UV-2100紫外分光光度计;日本岛津UV—260紫外分光光度计;751—GW(上海分析仪器厂)。     

基于光线传感器的手机光度计设计与应用

利用智能手机的光线传感器设计了一款简易光度计,并为其开发了安卓手机应用,可以在线查看样品信号,自动计算吸光度值。此款简易光度计采用了液相色谱紫外检测器的流通池作为样品吸收池,利用光纤传导光信号,可以大幅降低试剂使用量。进行一次测试只需要使用约200μL样品,有效降低了实验室废液回收量。利用该光度计对铁离子标准溶液进行测定,在测定浓度范围内,吸光度与样品浓度具有良好的线性拟合关系,其中R2=0.9991,可取代化学实验中的传统分光光度计。利用该光度计进行实验可以强化学生对仪器和实验原理的理解,有利于培养创新意识。     

加速法测定药物有效期的虚拟仪器系统设计与应用

本文采用722S型分光光度计的串行口与计算机通信,构建了基于LabVIEW测定药物有效期的虚拟仪器系统,实现了分光光度计的时间扫描、数据储存、数据处理与结果生成等,避免了人工测定时需要多人协同操作的繁琐和人为误差,提高了测量的精确度。应用该系统测得硫酸链霉素溶液的有效期为250 min,其反应的活化能为67kJ/mol,同时在相同实验条件下,人工实验测定该硫酸链霉素溶液的有效期为231min,反应的活化能为65kJ/mol,效果良好,且该系统还具有人机对话友好、操作简单、功能易扩展等诸多优点。     

原子吸收光谱法测定锰白铜(BMn3—12)中的镁

锰白铜中镁的测定,过去多采用化学法,操作较繁。本文研究了原子吸收光谱法,用镧作“外加基体”,控制共存元素的干扰,可以不必分离共存元素,不需多种试剂处理,仅用镁的纯水含镧标准溶液制做工作曲线,测定锰白铜中的镁,方法简单而快速。测定的最佳范围是:待测溶液中锰白铜用量为每毫升低于0.8毫克时,镁的含量范围为0.05—1.00微克/毫升。方法的相对标准偏差小于±10％,与化学法比较结果一致。实验 (一)仪器和试剂 1.原子吸收分光光度计: Hilger     

微波辅助化学浴快速沉积Eu:YVO4薄膜

应用简单有效的微波辐射辅助化学浴技术快速沉积了Eu:YVO₄纳米颗粒膜. 所沉积的Eu:YVO₄薄膜均匀、密实、镜面. 产物用X射线衍射仪、原子力显微镜、紫外分光光度计和荧光分光光度计进行测试、表征和分析. 结果表明所得Eu:YVO₄薄膜由纳米颗粒组成, 具有高的(200)择优取向, 结晶性良好, 在紫外光激发下具有良好的荧光发射性能.     

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.     

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.     

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.     

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.     

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.