溶胶-凝胶基质修饰的镉离子选择性电极

一种以CdS为活性物质,用溶胶 凝胶技术制作的新型镉离子选择性电极。电极的斜率为29mV/decade,线性范围为1.0×10-1～6.0×10-5mol/L,检测下限为4.5×10-5mol/L,适宜的pH3.2～5.9,并对回收率进行了测定。     

甲硫醇离子选择性电极的研制及其在甲胺磷残留量测定中的应用

本文以甲硫醇银及硫化银为电活性材料制得对甲硫醇离子有选择性响应的固态膜离子选择性电极。在pH为9.3的0.035mol/L Na_2B_4O_7-0.1mol/L NaOH-0.1mol/L Na_2SO_3介质中,电极的线性响应范围为5×10~(-6)～1×10~(-2)mol/L,响应斜率为58mV/pX。蔬菜中甲胺磷的残留量可以用乙酸乙酯或甲醇水溶液提取后,利用其在碱性条件下水解生成甲硫醇离子的特性用本电极测定,检测限2μg/g,设备简单,操作方便。     

溶胶-凝胶膜修饰的碘离子选择性电极

用溶胶-凝胶包埋硝酸银制备了碘离子选择性电极.电极对I-离子在10-1~10-7mol/L浓度范围内呈Nernst响应,斜率为58.321 mV/pI-,检测下限为4.6×10-8mol/L,回收率为97.4%~103.2%.     

2,4-二羟基苯甲醛缩硫脲合汞(II)为中性载体的高选择性碘离子电极的研究

报道了基于2,4_二羟基苯甲醛缩硫脲合汞(Ⅱ)为载体的溶剂聚合膜阴离子敏感电极,该电极对碘离子(I-)具有高的电位选择性和灵敏度,且呈现反Hofmeister选择性行为,其选择性序列为I->Sal->SCN->-4ClO>Br->-2NO>3-NO>32-SO>Cl->2-4SO。该电极电位对碘离子呈近能斯特响应,其线性范围为2.0×10-6～1.0×10-1mol/L,斜率为-68.6mV/dec,检出限为6.0×10-7mol/L。将电极用于加碘盐中碘含量的测定,结果令人满意。     

2,4-二羟基苯甲醛缩硫脲合汞(Ⅱ)为中性载体的高选择性碘离子电极的研究

报道了基于2,4-二羟基苯甲醛缩硫脲合汞(Ⅱ)为载体的溶剂聚合膜阴离子敏感电极,该电极对碘离子(I-)具有高的电位选择性和灵敏度,且呈现反Hofmeister选择性行为,其选择性序列为I-＞Sal-＞SCN-＞ClO-4＞Br-＞NO-2＞NO-3＞SO2- 3-＞Cl-＞So2- 4.该电极电位对碘离子呈近能斯特响应,其线性范围为2.0×10-6～1.0×10-1mol/L,斜率为-68.6 mv/dec,检出限为6.0×10-7 mol/L.将电极用于加碘盐中碘含量的测定,结果令人满意.     

硒代胱氨酸在银电极上的电化学行为及其定量分析

研究了硒代胱氨酸 (SeCys)于0.03mol/L的硼砂 -NaOH( pH9.5)介质中在银电极上的电化学行为 ;实验发现在 -0.62V和 -0.68V(vsSCE)处存在一对氧化还原峰 ,其峰电流与硒代胱氨酸浓度具有良好的线性关系 ,由此建立了SeCys的电分析化学测定方法, (1)循环伏安法 ,其线性范围为8.6×10 -9～1.1×10 -7mol/L,检出限为4.3×10 -10mol/L, (2)二次微分线性扫描伏安法 ,其线性范围为2.2×10 -10～1.0×10 -8mol/L,检出限为8.6×10-11mol/L;该法应用于中药黄芪中SeCys含量的测定 ,结果令人满意 ;该文还探讨了硒代胱氨酸在上述条件下的电极反应机理     

PVC膜十二烷基硫酸根离子选择电极的研制和应用

本文研制了以N263-MoO_4~(-2)缔合物为活性材料制成的十二烷基硫酸根PVC型膜电极。电极具有较好的选择性与灵敏度。检出限为3×10~(-7)mol/L,线性范围为2×10~(-3)—5×10~(-7)mol/L,其斜率为59±0.5mV(25℃),与理论值吻合。电池的组成如下: Ag/AgCl|0.1mol╱L NaCl|PVC敏感膜|试液‖SCE 本电极很成功地应用于测定牙膏及头发乳中的十二烷基硫酸根离子的含量。与其他方法对比,结果吻合。本电极取材容易,制作、处理及组装简单,便于在实际中应用。     

钠型蒙脱石修饰碳糊电极测定微量的铜离子

报道了一种高灵敏度 ,快速测定水体中铜离子的化学修饰碳糊电极。详细研究了测定铜离子的条件。该修饰电极测定铜离子的线性范围为 1× 1 0 - 9～ 1 .5× 1 0 - 7mol/L ,富集 6min后的检出限为 3× 1 0 - 10 mol/L。该方法简便、快速、灵敏。用该修饰电极测定了实际水样中的铜离子 ,平均回收率为 1 0 0 .8%。     

掺杂2,9-二甲基-4,7-二苯基-1,10-邻二氮菲的石蜡碳糊铜离子选择性电极的研究

采用液体石蜡作为粘合剂,将2,9-二甲基-4,7二苯基-1,10邻二氮菲(又称为Bathocuproin)与碳粉混合,制备了新型铜离子选择性电极。试验了测定微量Cu的最佳条件,考察了电极的性能。在pH 6.7的5×10-3mol/L柠檬酸钠溶液中,Cu浓度在1×10-6~1×10-3mol/L范围内有能斯特响应;响应时间小于60 s;考察了10余种离子的干扰情况,多数对测定没有影响。利用该铜离子选择电极对电镀废液和铜矿浸出液中的Cu2+浓度进行了测定,取得了较好的结果。该铜离子选择性电极稳定性好,精密度高,使用寿命长,有望在实际的生产、研究领域得到广泛推广应用。     

盐酸普鲁卡因离子选择性电极的研制及应用

用盐酸普鲁卡因离子缔合物为电活性物质,以11邻苯二甲酸二正辛酯和邻苯二甲酸二正丁酯为增塑剂,研制成了以PVC为基质膜的盐酸普鲁卡因离子选择性电极.盐酸普鲁卡因浓度在1.0×10-4～2.5×10-2 mol/L范围内时,电极电位服从能斯特方程.响应斜率为56.6 mV/△PC,检测下限为3.16×10-5mol/L,对盐酸普鲁卡因的回收率为95.0%～105%,相对标准偏差为4.6%.本文还考察了电极的各种性质,测定了20种常见离子的选择性系数.方法巳用于实际样品中的盐酸普鲁卡因测定,与常规方法对照,相对误差为4.1%.     

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.