双烯醇酮乙酸酯的极谱催化波及应用研究

采用线性扫描极谱技术,研究了在H2O2存在下双烯醇酮乙酸酯的极谱催化波。结果表明,在pH 4.0±0.5的B-R缓冲溶液、8.0×10-3mol/L H2O2溶液和0.1 mol/L KCl底液中,双烯醇酮乙酸酯于-1.01 V处产生一极谱催化波;其一阶倒数峰电流与双烯醇酮乙酸酯的浓度在1.0×10-8~1.0×10-7mol/L范围内有良好的线性关系,iP′=1.384×1011c 2.374×104(nA/s),相关系数r=0.9991;讨论了极谱催化波的产生机理。     

薯蓣皂甙元的极谱催化波及其应用

采用线性扫描极谱技术,研究了薯蓣皂甙元(C27H42O3,简称皂素)的极谱催化波及应用。结果表明,在pH=5.3±0.5的BR缓冲溶液、0.1mol/LKCl和8×10-3mol/LH2O2的底液中,皂素产生极谱催化波,其一阶导数波的峰电位在-1.05V(vs.SCE)处,峰电流与皂素浓度在1.0×10-8～8.0×10-8mol/L范围内有良好的线性关系,线性回归方程:i′P=7.322×108c+3.919(μA/s),相关系数r=0.9984,检出限为1.0×10-8mol/L;该波为不可逆吸附、平行催化波。建立了测定皂素的新分析方法,并测定了黄姜中皂素的含量。     

过硫酸钾存在下吸附缔合/平行催化波法测定酮洛芬

应用线性扫描极谱法和循环伏安法,在0.10 mol/L NH4C l-NH3.H2O(pH 9.5)-0.01 mol/L K2S2O8底液中,对酮洛芬(KPF)的电化学行为进行了研究。在该底液中KPF于峰电位-1.37 V(vs.SCE)处产生1个灵敏的吸附缔合/平行催化波。该极谱催化波中S2O82-有双重作用:①S2O82-作为配位体与吸附在电极表面的质子化KPF形成缔合物,引起峰电位负移;②S2O82-及其还原中间产物SO4-作为氧化KPF羰基经单电子单质子还原的自由基,产生了极谱催化,使峰电流显著增加。该极谱催化波的二阶导数峰峰电流与KPF浓度在1.97×10-8~3.94×10-6mol/L范围内呈线性关系,检出限为6.57×10-9mol/L(3σ)。对3.94×10-7mol/LKPF溶液进行13次平行测定,RSD为1.24%。该催化波的分析灵敏度比相应还原波提高20倍。该方法已用于药剂中KPF的测定。     

铜( Ⅱ )存在下的催化极谱波检测福美双

报道了在酒石酸-酒石酸钾钠-K2S2O8体系中福美双与Cu2 的极谱催化波。在0.1mol/L酒石酸-酒石酸钾钠(pH=5.5)缓冲液 3.0×10-3mol/LK2S2O8 4.0×10-6mol/LCu2 底液中,极谱催化波峰电位Ep=-0.8V(vs.SCE);福美双的二阶导数峰峰电流Ip″与其浓度在1.0×10-8~1.0×10-6mol/L范围内呈良好的线性关系(r=0.9994),检出限为2.0×10-9mol/L。相对标准偏差(RSD)为1.17%(n=10)。在福美双浓度为1.0×10-6mol/L时,福美双还原波峰电流为12nA,而相应的福美双在Cu2 存在下的催化还原峰电流为1.5μA,即灵敏度提高了125倍。样品的检测回收率为83.8%~91.4%。该方法灵敏、简单、快速。     

碘酸钾存在下萘丁美酮的极谱催化波法测定

本文报道了灵敏、快速测定萘丁美酮的新方法。在0.10 mol.L-1HAc-NaAc(pH 4.7)支持电解质中,萘丁美酮产生一极谱波,峰电位Ep=-1.12 V(vs.SCE)。加入KIO3后,该极谱波被催化,峰电流增加约30倍,峰电位基本不变,产生一灵敏的极谱催化波。其二阶导数峰峰电流ip″与萘丁美酮浓度在2.0×10-7~4.0×10-5mol.L-1范围内呈线性关系(r=0.9970,n=8),检出限为1.0×10-7mol.L-1。该方法可用于药物制剂中萘丁美酮含量的测定。     

防晒剂2，2’，4，4＇-四羟基二苯甲酮在B—R缓冲体系中的极谱行为

用线性扫描极谱法系统研究了2,2′,4,4′-四羟基二苯甲酮(简称BP-2)在不同缓冲体系中的极谱行为.实验表明,在pH=2.25的B-R缓冲溶液中,BP-2的一阶导数峰电位为-1.12 V,其峰电流与浓度在5.0×10-6～9.0×10-5mol/L范围内的对数值有良好的线性关系,线性方程为ip′(nA/s)=11 457 2 133×lgc(mol/L),相关系数为0.9998.BP-2的微分循环伏安研究表明,该极谱波为不可逆还原波;初步讨论了电极反应机理.     

防晒剂2,2′,4,4′-四羟基二苯甲酮在B-R缓冲体系中的极谱行为

用线性扫描极谱法系统研究了2,2′,4,4′-四羟基二苯甲酮(简称BP-2)在不同缓冲体系中的极谱行为。实验表明,在pH=2.25的B-R缓冲溶液中,BP-2的一阶导数峰电位为-1.12 V,其峰电流与浓度在5.0×10-6~9.0×10-5mol/L范围内的对数值有良好的线性关系,线性方程为ip′(nA/s)=11 457 2 133×lgc(mol/L),相关系数为0.9998。BP-2的微分循环伏安研究表明,该极谱波为不可逆还原波;初步讨论了电极反应机理。     

极谱催化波法测定中草药中的芦丁

基于芦丁在K2S2O8存在下产生的极谱催化波,拟定了测定中草药中芦丁的方法。在0.1 mol/L HAc-NaAc(pH 3.60±0.05),8×10-3mol/L K2S2O8支持电解质中,芦丁催化波峰电位为-1.37 V(vs.SCE),它的二阶导数峰电流与其浓度在1.6×10-6~1.6×10-5mol/L范围内呈线性关系(r=0.9960,n=6)。检出限为9.013×10-11mol/L,回收率为96.18%~102.66%。样品可不经分离,直接测定。采用该方法测得山楂和川明参中芦丁的质量分数分别为1.78%和1.60%。     

雷公藤内酯酮的极谱行为研究

在不同pH值的相关体系中,雷公藤内酯酮可产生两个还原波,其峰电流和峰电位两者均受酸度的影响;然而,在B-R缓冲体系中,虽然峰电流受溶液酸度的影响,但峰电位基本上保持不变。在pH=5.4的B-R缓冲体系中,雷公藤内酯酮的两峰的峰电位分别为-0.06 V和-1.05 V(vs.SCE);两峰的峰电流与雷公藤内酯酮的浓度在3.16×10-6~3.16×10-5mol/L的范围内成良好的线性关系。循环伏安研究表明,两波都是不可逆吸附波。     

直接快速极谱法测定生物样品中的痕量铬

报道了在亚硝酸钠-2,2′-联吡啶-溴化十六烷基三甲铵(CTMAB)中铬(Ⅵ)的极谱催化波。在0.24mol/LNaNO2-4×10-5mol/L2,2′-联吡啶-1.6×10-5mol/LCTMAB(pH8.0)底液中,极谱催化波峰电位EP=-1.39V(vs.SCE),其峰电流与铬(Ⅵ)浓度在0～20ng/mL范围内有良好的线性关系。方法可用于测定生物样猪肝及猪肾中痕量铬(Ⅵ)。对极谱波的性质进行了初步探讨。     

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.