镍电极开路电位测定微量硼氢根离子

实验采用循环伏安法,用镍电极代替铂铑等贵金属电极测定了碱性体系中不同硼氢根离子浓度下的开路电位,得出了研究电极的开路电位(-0.355～-0.280 vs.SCE/V)与微量硼氢根离子浓度的对应关系,并用于监测电解偏硼酸钠制备硼氢化钠体系中微量硼氢根离子,同时计算了该方法的误差.结果表明,测量结果的相对标准偏差为2.2%;回收率为98.4%.该法简单、快速,可测定10-5～10-3 mol/L范围的硼氢根离子浓度.     

壳聚糖碳纳米管修饰电极测定痕量铜

建立了用自制的碳纳米管壳聚糖修饰电极测定Cu^2＋离子的电分析方法,在0．10mol／L的CH,COOH—CH3 COONa（pH4．2）缓冲溶液中,以此修饰电极作为工作电极,以-0．60V为富集电位,搅拌富集6min后,用差分脉冲伏安法测定-0．10V处的峰电流。结果发明,该电极对铜离子吸附的灵敏度较高,当铜离子浓度为1．0×10^-6～4．6×10^-5mol／L时,线性关系良好,相关系数为0．9997,对含铜血清样本进行测定,取得了满意的结果,加标回收率在98％～102％之间。     

聚色氨酸／镍复合膜修饰电极测定抗坏血酸的研究

采用电化学聚合法制备了聚色氨酸／镍复合膜修饰玻碳电极,研究了抗坏血酸在该修饰电极上的电化学行为,建立了测定痕量抗坏血酸的新方法。在pH6．2的磷酸盐缓冲溶液中,抗坏血酸在修饰电极上产生一个灵敏的氧化峰,采用线性扫描伏安法测定,其氧化峰电流与抗坏血酸浓度在2．0×10^-6 -1．0×10^-3mol／L范围内呈良好的线性关系,检出限为5．0×10^-7mol／L。对1．0×10^-4mol／L抗坏血酸溶液平行测定6次,测定结果的相对标准偏差为1．9％。该法用于片剂中抗坏血酸含量的测定,加标回收率为97．8％～101．2％。     

铅笔芯微电极的制备及其在电化学法测定抗坏血酸中的应用

研究了一种用铅笔芯制作的微电极的电化学行为,并利用这种电极进行抗坏血酸含量的测定。结果表明：在5．0×10^-5～1．0×10^-2mol／L的浓度范围内,抗坏血酸的氧化峰电流与其浓度呈线性关系,相关系数／=0．9993,检出限为2．5×10^-5mol／L（S／J7v=3）。对2．5×10^-3mol／L抗坏血酸溶液平行测定6次,测定结果的相对标准偏差为4．7％。该电极用于维生素c片中抗坏血酸含量的测定,加标回收率为94．8％-99．8％。     

铜（III）配合物-罗丹明6G体系流动注射化学发光法测定头孢米诺钠

在酸性条件下,头孢米诺钠对铜（III）配合物-硫酸-罗丹明6G化学发光体系有强烈的增敏作用,据此建立了流动注射化学发光法定量分析头孢米诺钠方法。头孢米诺钠浓度在2．0×10^-7-6．0×10^-6g／mL范围内与化学发光强度呈良好的线性关系,相关系数r=0．99969,检出限为1．4×10^-7g／mL。对2．0×10^-7g／mL头孢米诺钠水溶液进行11次平行分析,测定结果的相对标准偏差为1．69％。利用该方法对鸡血样品和头孢米诺钠针剂中头孢米诺钠的含量进行测定,加标回收率为90．2％～102．1％。     

新型水杨醛缩DL-甲硫氨基酸合铜(Ⅱ)配合物中性载体的碘离子选择性电极的研究

以水杨醛缩现．甲硫氨基酸合铜（Ⅱ）[Cu（Ⅱ）-HBMT]为中性载体,制备了一种对碘离子（I^-）具有优良的电位响应特性并呈现出反Hofmeister选择性行为的离子电极,其选择性次序为：I^-〉Sal^-〉SCN^-〉ClO4^-〉SO3^2-〉No3^-〉NO2^-〉Br^-〉Cl^-〉H2PO4^-。该电极在pH2．0的磷酸盐缓冲体系中具有最佳的电位响应,在5．0×10^-6-0．1mol／L I^-浓度范围呈近能斯特响应,斜率为-57．5mV／pI^-（25℃）,检出限为1．6μmol／L。采用交流阻抗和紫外光谱分析技术研究了配合物中心金属离子以及配合物本身的结构对电极电位响应行为的作用机理。将该电极用于药物含碘量的测定,获得满意的结果。     

铁氰酸镍膜修饰金电极的研制及应用

通过层层组装的方法,将Ni^2＋和[Fe（CN）6]^3-交替沉积在巯基乙酸功能化的金电极表面．首次成功制备了铁氰酸镍多层膜修饰电极,用循环伏安法研究了该多层膜的电化学行为,实验表明峰电流随膜层数的增加而增加,膜均匀增长．该修饰电极对一价金属离子Na^＋,K^＋,NH4^＋具有选择性响应,尤其对K^＋存在准能斯特响应,响应范围0．01～1．0mol／L;而且该电极对抗坏血酸（AA）和S2O3^2-体系的氧化具有良好的电催化作用,线性范围分别为：1．14×10^-4～1．14×10^-3mol／L和5．0×10^-4～3．1×10^-3mol／L．     

高锰酸根褪色光度法测定食盐中的微量碘离子

在稀硫酸介质中，碘离子能快速、定量地还原高锰酸根，在加入碘离子前后，高锰酸钾溶液在波长525nm处的吸光度发生显著变化，且吸光度之差ΔA与加入的碘离子的浓度成正比，确定了最佳反应条件，建立了高锰酸根褪色光度法测定食盐中微量碘离子的新方法。方法的线性范围为0-20μg／mL，线性回归方程为ΔA=0．0165c 0．0041，相关系数r=0．9987，检出限为0．17μg／mL。用于食盐中微量碘离子的测定，加标回收率为91．0％～95．0％．相对标准偏差为0．35％～0．75％。     

以两种杯[4]芳烃衍生物为载体的PVC膜季铵盐正离子选择电极的研究

研究了两种新型杯[4]芳烃衍生物5，ll，17，23-四叔丁基-25，26，27，28-四-[3．(甲氧基羰基)苄氧基]杯[4]芳烃(I)和5，ll，17，23-四叔丁基-25，26，27，28-四-[3-(乙氧基羰基)苄氧基]杯[4]芳烃(Ⅱ)为载体的PVC膜电极的响应行为；实验结果表明，两电极对季铵盐正离子均具有优良的能斯特电位响应性能，以(I)为载体的电极对Bu4N^ 、Et4N^ 和Me4N^ 的线性响应范围分别为10^-6～10^-1mol／L、10^-6～10^-1mol／L和10^-4～10^-1mol／L，相应的斜率为59．2、55．0和55．9mV／pc；以(Ⅱ)为载体的电极对Bu4N^ 、Et4N^ 和Me4N^ 的线性响应范围分别为10^-6～10^-1mol/L，10^-5～10^-1mol/L和10^-4～10^-1mol／L，相应的斜率为59．8、56．6和56．0mV／pc；电极具有读数稳定，重复性好，可在pH值较宽范围内测定等优点；将该电极用于药品溴丙胺太林中丙胺太林含量的测定，所得结果与药典法基本一致。     

硅基分子印迹技术制备铜离子选择电极

以3-（2-氧基乙基氨基）丽基三甲氧基硅烷作为功能分子,铜离子为模板,将分子印迹技术与溶胶凝胶技术相结合,制备了铜离子选择电极,探讨了电极的响应机理．该电极对铜离子有较好的能斯特响应特性,其线性响应范围为5．00×10^-2～3．98×10^-6mol·L^-1,斜率为31．5mV／pC（-logc）,检出限为1．00×10^-6mol·L^-1．同时该电极显示了较好的选择性,重现性和稳定性．     

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.     

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.     

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.     

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.