线性扫描极谱法检测环境水样中四环素

基于四环素在pH=5.5的柠檬酸-柠檬酸钠缓冲溶液中可产生一灵敏的还原峰,建立了一种测定四环素的极谱新方法。在优化条件下,于起始电位-0.9 V(vs.SCE),峰电位-1.4V(vs.SCE),四环素浓度分别在0.1~30、30~90μg/mL范围内与峰电流呈现良好的线性关系,检出限为0.0024μg/mL。该方法直接用于环境水样中四环素的检测,回收率为97.8%~102.9%。用线性扫描极谱法研究了检测体系的电化学行为,证明了极谱波为不可逆还原吸附波,并讨论了电极反应机理。     

金属-4-(2-吡啶偶氮)-间苯二酚(PAR)络合物极谱波研究(Ⅰ)——钒(V)-PAR-NaClO3体系的极谱催化波

钒(V)-PAR络合物在NaClO₃存在下产生一灵敏的极谱催化波.峰电位为-0.1V(SCE).该催化波具有吸附和动力波的特征.     

灰黄霉素的伏安行为及其测定的研究

灰黄霉素在0.1mol LHAc NaAc底液(pH5.0)中,产生灵敏的线性扫描极谱导数峰,峰电位为-1.28V(vs.SCE),峰电流与灰黄霉素浓度在2.0×10-7～2.0×10-6mol L范围内成线性关系。用于灰黄霉素片剂的测定。用线性扫描和循环伏安法等手段研究体系的伏安行为,结果表明,该体系属具有吸附性的不可逆过程。     

均相伏安免疫法检测白喉类毒素和白喉抗毒素

白喉类毒素在pH9.4的0.1MNH₄Cl-NH₃·H₂O底液中改性,产生还原峰和氧化峰,峰电位分别为-1.52V和-1.46V(vs.SCE)。用单扫示波极谱法得到还原(或氧化)峰的峰电流与白喉类毒素浓度在2.5-180μg/ml范围内均呈良好线性关系。用微分脉冲极谱法可检测浓度低至0.3μg/ml的白喉类毒素。由特异性免疫结合反应,微分脉冲极谱法测得白喉类毒素的峰电流降低值与白喉抗毒素浓度在2.5×10^-6-5×10^-5IU/ml范围内呈正比关系,可测定白喉抗毒素浓度。方法简便、快速、灵敏度较高,可均相测定。用氧化峰电流测定百日咳菌苗-白喉-破伤风类毒素混合剂中白喉类毒素的含量,结果满意。     

银在脱乙酰壳多糖化学修饰电极上的电化学行为及分析应用

用脱乙酰壳多糖化学修饰电极为工作电极,阳极溶出伏安法测定痕量银。在pH4.0的0.1mol·L-1邻苯二甲酸氢钾和0.1mol·L-1硫氰化溶液中,起始电位一0.80V,终点电位＋0.5V,富集时间3min,以0.1V·s-1扫速阳极溶出,峰电位在一0.075V(vs.Ag/AgCl),银浓度在0.02～1.0μg·m1-1范围内与峰高呈线性关系,提高了测定灵敏度,用于矿样测定,无需分离,结果满意。用紫外光谱和拉曼光谱研究了该法的电极过程机理。     

极谱法测定氯霉素的研究

在0.1mol/L的KCl底液中,用单扫示波极谱法可以得到一个灵敏的氯霉素导数还原峰,其峰电位为-0.74V(vs.SCE),峰电流与氯霉素溶液的浓度在1.5×10-7~2.0×10-5mol/L范围内呈线性关系,检出限为2.0×10-8mol/L,对氯霉素在汞电极上的电化学行为特别是对其吸附性能进行了探讨,该法用于注射液中氯霉素的测定,回收率在96.9%~100.3%之间。     

镉-Ⅰ~--亮绿配合物在盐酸-十二烷基硫酸钠介质中的极谱吸附波

镉-I~-亮绿配合物在十二烷基硫酸钠存在下的盐酸介质中,产生灵敏的阴极二次导数极谱波,其峰电位为-0.76V(vs.SCE),镉的检出限为0.00016μg/mL,线性范围为0.1～5μg/25mL,可用于高温合金中镉的测定。对极谱波的性质、机理及配合物组成也进行了研究。     

芦丁的电化学伏安行为及其应用

芦丁在0.1mol/L Tris-HCl缓冲溶液(pH=8.3)中产生灵敏的线性扫描极谱峰,峰电位EP=-1.10V(vs.Ag/AgCl).峰电流与芦丁浓度在7×10-7~9.8×10-6mol/L范围内呈良好的线性关系.可用于乌拉尔甘草内黄酮含量的测定.线性扫描和循环伏安法测试表明,该体系属具有吸附性的准可逆过程体系.     

PAN-蛋白质络合物的极谱吸附波及其应用

在0.05 mol/L HAc溶液中,PAN-牛血清白蛋白/人血清白蛋白络合物在-0.58 V(vs.SCE)处产生一灵敏吸附还原峰,峰电位较之游离PAN还原峰负约0.28 V,峰电流与牛血清白蛋白、人血清白蛋白浓度在0.1～12 mg/L,0.1～11 mg/L范围内呈线性关系;检测限均为0.05 mg/L。运用该法测定了人血清样品蛋白质含量。     

生理条件下对苯二酚的电化学行为及电极产物的色谱鉴定

用循环伏安法研究了对苯二酚在玻碳电极上的电化学行为,从循环伏安图上看出当在0至1．6V电位间连续扫描20次,在0．63V左右可见到一氧化峰电位,其峰电流随扫描次数的增加而减小。说明电极反应为不可逆过程。然而,如改变在-1．4～1.6V电位间扫描,仅数次扫描后即可在Epa=0．25V和Epc=-0．08V处见到一对氧化还原峰电位,说明了此过程为一可逆过程。同时,对电极反应的产物用RHPLC进行研究和鉴定,从色谱图所示结果与电化学法所得结果一致。根据此工作的研究结果对苯二酚在呼吸链中所产生的作用进行了探讨。     

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.