紫外光谱法测定印制线路板废水中的铜

白杨素在紫外区内具有强吸收,Cu2+加入后会导致其吸光度显著下降,且吸光度的降低与Cu2+的浓度呈良好的线性关系,基于此建立了紫外光谱法测定Cu2+的新方法。通过对缓冲溶液体积、p H、白杨素浓度等进行考察和优化,在p H 8.28、9.0×10-2mol/L的六亚甲基四胺(HM TA)-HCl缓冲溶液中,4.0×10-8~1.0×10-6mol/L范围内,Cu2+浓度与吸光度降低成正比,线性方程为ΔA=0.508 c-0.0147(10-6mol/L)(R=0.99604),检出限为7.08 nmol/L(S/N=7),对4.0×10-8mol/L Cu2+溶液平行测定7次,ΔA的相对标准偏差为4.0%。对印制线路板废水中的铜进行了测定,测得结果与EDTA滴定法基本一致。     

藏红T与六偏磷酸钠的相互作用及在食品分析中的应用

对阳离子荧光染料藏红T（ST）在食品添加剂六偏磷酸钠（SHMP）存在时的溶液状态的荧光光谱及吸收光谱进行了研究。 结果发现,在醋酸-醋酸钠缓冲条件下,SHMP使ST溶液发生自聚集,同时因静电作用二者形成杂化聚集体,导致ST的荧光强度和吸光度降低且在476 nm处出现新的吸收峰,但ST的荧光寿命没有发生明显的变化,表明SHMP静态猝灭ST的荧光。 根据SHMP存在时ST吸光度的变化,建立了一种检测食品添加剂六偏磷酸钠的新方法,线性范围为1.0×10-6~1.1×10-5 mol/L,检测限为3.4×10-7 mol/L。 方法成功应用于饮料中六偏磷酸钠的测定,相对标准偏差小于4.6%,回收率在95.0%~104.0%之间。     

利用对三溴偶氮胂-锆(Ⅳ)络合物的置换反应光度法测定草酸

在0.20 mol.L-1盐酸介质中,锆(Ⅳ)与三溴偶氮胂形成1:1蓝紫色络合物,加入草酸可置换络合物中的三溴偶氮胂,使显色溶液的吸光度升高,草酸的浓度与吸光度升高值成正比.在506 nm波长处,草酸浓度在1.0×10-4～6.5×10-4mol.L-1范围内遵守比耳定律.方法的表观摩尔吸光率ε506nm:1.23×10.L·mol-1·cm-1,检出限为0.074 mg·L-1.方法已直接用于地下水以及西红柿样品中草酸含量的测定,所得结果与文献[7]的方法结果相符.测定值的相对标准偏差(n=13)均小于2%,所测得的回收率在95.7%～103.9%之间.     

5-（5-氯-2-吡啶偶氮）-2,4-二氨基甲苯褪色光度法测定牛血清蛋白

在pH 2.4的Britton-Robinson(B-R)缓冲溶液中,5-(5-氯-2-吡啶偶氮)-2,4-二氨基甲苯(5-Cl-PADAT)与牛血清蛋白相互作用形成复合物而导致溶液吸收光谱发生变化,用分光光度法对光谱变化进行了研究.5-Cl-PADAT溶液在430 nm处有一个强的特征吸收峰,当在其溶液中加入牛血清蛋白后,溶液发生褪色现象,吸收峰强度降低,且没有新的吸收峰出现,吸光度降低值(ΔA)与牛血清蛋白的浓度(c)成正比.在选择的最佳试验条件下,牛血清蛋白浓度与ΔA的线性方程为ΔA=0.8141c+0.0041(r=0.9996),线性范围为1.071×10-9～5.902×10-9 mol/L,检出限为5.36×10-10 mol/L,该方法的回收率为96.9%～107.1%,测定结果的相对标准偏差为1.4%～2.3%(n=6).     

次甲基兰-溴酸钾体系催化光度法测定溴化物

建立了测定微量的溴化物的催化动力学光度分析方法。在酸性介质中,KBr对KBrO3氧化次甲基兰的反应具有明显的催化作用,使次甲基兰的吸光度减小。结果表明:最大吸收波长为665 nm,KBr浓度在2.0×10-6～2.8×10-5mol/L时与吸光度△A呈良好的线性关系。其线性回归方程为△A=0.0122 c+0.0173,R2=0.9992,检出限为1.1×10-6mol/L,回收率99.8%～101%。RSD为0.47%～0.69%。该方法灵敏度和准确度均较高,适用于药品中微量KBr的测定。     

纳米金光度法测定药物中盐酸小檗碱

氯金酸用葡萄糖还原制得纳米金,最终获得浓度为2.4×10-4mol.L-1且呈酒红色的纳米金悬浮溶液。试验证实纳米金颗粒被均匀地分散在悬浮溶液中,其吸收光谱中在525 nm波长处出现一吸收峰。当在纳米金悬浮溶液中加入盐酸小檗碱,由于两者间的静电结合导致溶液在525 nm波长处的吸光度降低,且其降低的幅度与盐酸小檗碱浓度在2.0×10-7～3.0×10-6mol.L-1范围内呈线性关系,其检出限(3S/N)为1.7×10-8mol.L-1。应用此方法分析了3个批号的药物盐酸小檗碱或片剂样品,所测得的结果与按药典方法测得结果相符。     

Ru(bipy)2+3-CO2-3-SO2-3-KClO3体系化学发光法测定空气中的二氧化硫

提出了Ru(bipy) 2+ 3-CO 2- 3-SO 2- 3-KClO 3体系化学发光法测定溶液中亚硫酸盐的方法.SO 2- 3浓度与化学发光强度在1.0×10-7～1.0×10-4 mol/L 范围内成正比,检出限为8.76×10-8 mol/L,对1.0×10-4 mol/L SO2-3溶液6次测定的相对标准偏差为2.9%.该法用三乙醇胺作为吸收液,成功地用于测定空气中二氧化硫的含量,结果满意.     

聚天青I/石墨烯修饰电极的电化学行为及对亚硝酸根的检测

制备了聚天青I/石墨烯修饰玻碳电极。用循环伏安法研究了溶液pH,扫描速率对聚天青I/石墨烯修饰电极的电化学行为的影响及修饰电极对NO-2的电催化作用。利用示差脉冲伏安技术检测NO-2,NO-2浓度在1.0×10-7~1.0×10-5mol/L的范围内,其氧化峰电流与浓度呈现良好的线性关系,检出限为3.7×10-8mol/L(S/N=3)。修饰电极已用于水体中NO-2的检测。     

天青A-BSA共振散射光谱研究及分析应用

考察了天青A与牛血清白蛋白(BSA)混合体系的共振散射光谱,发现天青A的加入能引起BSA的共振散射光谱强度明显增强,通过优化实验条件建立了测定蛋白的新方法.在p H=3.78的磷酸氢二钠-柠檬酸缓冲溶液中,固定天青A浓度为1.00×10-5mol/L,当牛血清白蛋白浓度在8.80×10-8~4.40×10-6mol/L范围内与体系的共振光散射强度值呈良好的线性关系,线性方程为IRLS=69.744c(mol/L)+59.359,相关系数r=0.992 8,检出限为3.28×10-8mol/L,方法应用于牛尿样品中白蛋白含量的测定,回收率在97%~106%之间,表明方法具有较高的准确度,结果令人满意.     

锆(Ⅳ)-偶氮胂Ⅲ褪色光度法测定茶叶和尿样中的草酸

建立了一种快速、简便及选择性好的测定茶叶和尿样中草酸的方法。该法基于在1.3mol/L的HCl介质中,锆(Ⅳ)与偶氮胂Ⅲ形成配比为1∶1的蓝绿色络合物,草酸的加入使溶液的吸光度降低,在一定的范围内,草酸的浓度与吸光度的降低成正比。草酸浓度在5.5×10-6～1.1×10-4mol/L范围内线性关系良好,相关系数为0.997,检出限(S/N=3)为2.30×10-6mol/L。方法用于一些生物样品中草酸含量的测定,结果满意。本法简便、快速,易被一般实验室采用。     

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.     

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.     

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.     

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.