锌电解液中痕量铜、镉、镍和钴的快速同时测定

研究了丁二酮肟 氨 氯化铵 柠檬酸钠 明胶 抗坏血酸体系中Cu(Ⅱ )、Cd(Ⅱ )、Ni(Ⅱ )和Co(Ⅱ )的络合物吸附波 ,建立了同时、快速测定锌电解溶液中这些痕量元素的新方法。Cu(Ⅱ )、Cd(Ⅱ )、Ni(Ⅱ )和Co(Ⅱ )分别在 - 0 44V、- 0 76V、- 1 0 7V和 - 1 2 4V左右产生灵敏的络合物吸附波。信噪比为 3时 ,其检测限分别为 1 0× 1 0 - 8mol/L、1 3× 1 0 - 8mol/L、2 9× 1 0 - 1 0 mol/L和 3 6×1 0 - 1 1 mol/L。铜、镉、镍和钴的浓度分别为 2 0× 1 0 - 8mol/L～ 2 0× 1 0 - 5 mol/L、3 0× 1 0 - 8mol/L～ 3 0× 1 0 - 5mol/L、5 4× 1 0 - 1 0 mol/L～ 5 4× 1 0 - 7mol/L和 6 8× 1 0 - 1 1 mol/L～ 6 8× 1 0 - 8mol/L时 ,与相应峰电流之间有良好的线性关系。方法已用于锌电解液中铜、镉、镍和钴的快速同时测定 ,相对标准偏差分别小于或等于 4 7%、5 1 %、4 9%和 5 3 %。     

水杨醛缩L-异亮氨基酸Schiff碱过渡金属Cu(Ⅱ), Zn(Ⅱ), Ni(Ⅱ)配合物的电化学合成及表征

采用Cu, Zn, Ni为“牺牲”阳极, 在无隔膜电解槽和含配体水杨醛缩L-异亮氨基酸Schiff碱的乙腈溶液中电解合成了Cu(Ⅱ), Zn(Ⅱ)和Ni(Ⅱ)配合物. 利用元素分析、红外光谱、紫外光谱、热分析等手段对配合物的结构进行了表征, 测定了Cu(Ⅱ)配合物的电化学性质. 结果表明, 配合物的化学组成为ML·nH2O(L=C13H15NO3, M=Cu(Ⅱ), Zn(Ⅱ), Ni(Ⅱ), n=1, 1, 2), 配合物具有相似的空间结构, 配体均以三齿进行配位; 电合成配合物的电化学效率Ef 接近0.5 mol/F[Zn(Ⅱ), Ni(Ⅱ)]和1.0 mol/F[Cu(Ⅱ)], Cu(Ⅱ)配合物中Cu(Ⅱ)L/Cu(Ⅰ)L电对的可逆半波电位Er1/2为-0.79 V.     

碳纳米管／纳米二氧化钛-聚苯胺载铂复合电极微分脉冲法测定葡萄糖

研究了多壁碳纳米管/纳米二氧化钛-聚苯胺载铂(CNT/nanoTiO2-PAn-Pt)复合电极对葡萄糖的电催化氧化作用。以0.5 mol/LKOH水溶液为底液,采用微分脉冲法在-0.5-0.2V电位区间扫描,在-0.33V(vs,SCE)附近产生的氧化电流峰灵敏度高且峰型好,故以此峰为定量峰。葡萄糖浓度在1.25×10-2~1.0×10-5mol/L与峰电流呈良好的线性关系,线性相关系数为0.99881,检出限为5.0×10-6mol/L。加入0.06m mol/L的抗坏血酸或0.3m mol/L的尿酸(模拟人血成份)均不干扰葡萄糖的测定。该电极对模拟血液中葡萄糖的测定,结果令人满意。     

碳纳米管/纳米二氧化钛-聚苯胺载铂复合电极

研究了多壁碳纳米管/纳米二氧化钛-聚苯胺载铂(CNT/nanoTiO2-PAn-Pt)复合电极对葡萄糖的电催化氧化作用.以0.5 mol/LKOH水溶液为底液,采用微分脉冲法在-0.5-0.2V电位区间扫描,在-0.33V(vs,SCE)附近产生的氧化电流峰灵敏度高且峰型好,故以此峰为定量峰.葡萄糖浓度在1.25×10-2～1.0×10-5 mol/L与峰电流呈良好的线性关系,线性相关系数为0.99881,检出限为5.0×10-6 mol/L.加入0.06m mol/L的抗坏血酸或0.3m mol/L的尿酸(模拟人血成份)均不干扰葡萄糖的测定.该电极对模拟血液中葡萄糖的测定,结果令人满意.     

有序介孔碳-壳聚糖修饰玻碳电极差分脉冲溶出伏安法测定痕量锡(Ⅱ)

将有序介孔碳(OMC)分散于壳聚糖(CTS)溶液,并用于修饰玻碳电极,制成有序介孔碳-壳聚糖修饰玻碳电极(OMC-CTS/GCE),用差分脉冲溶出伏安法研究锡(Ⅱ)在该电极上的溶出伏安特性。实验发现,在1.0mol/L盐酸中,锡(Ⅱ)在-1.2V处被富集在修饰电极表面,在0.0～+1.0V电位范围,以100mV/s的速率扫描,锡(Ⅱ)在+0.35V处产生一灵敏的溶出峰,峰电流与锡(Ⅱ)的浓度在5.0×10-8～1.0×10-5mol/L范围内呈良好的线性关系,检出限(S/N=3)为2.2×10-9 mol/L。方法用于合金中痕量锡(Ⅱ)的测定,结果同火焰原子吸收光谱法(FAAS)测定结果一致。     

2-(2-噻唑偶氮)-对-甲酚螯合物反相高效液相色谱同時分离测定镍、钴的研究——合金中微量钴和镍的测定

本文研究了2-(2-噻唑偶氮)-对-甲酚(TAC)与镍(Ⅱ)、钴(Ⅱ)螯合物的柱前衍生条件和液相色谱的分离条件。于KYWG-C_(18)柱上,用含有0.03mol/L KH_2PO_4-Na_2HPO_4(pH7.77)和2.5×10~(-4)mol/L TAC的甲醇-四氢呋喃-水(40∶10∶50 V/V)混合液为流动相,流速为1.0mL/min。于580nm处检测。该法用于四种标准合金中镍和钴的测定,回收率在98%～101.5%之间。Ni(Ⅱ)和Co(Ⅱ)的检出限(信噪比为2∶1)分别为0.2ng和1.5ng。建立了同时测定镍,钴的高灵敏、高选择性,快速的HPLC-光度法。     

差分脉冲溶出伏安法测定陶瓷器皿中铅和镉的溶出率

采用4%的乙酸浸泡陶瓷样品24 h,应用同位镀汞差分脉冲溶出伏安法测定了陶瓷样品中微量重金属铅、镉的溶出量。以0.1 mol/L的硝酸溶液做底液,0.1 mol/L的KCl溶液做支持电解质,2 g/L的Hg2+溶液做镀汞液,测得铅的溶出峰电位为-0.5 V(vsSCE),镉的溶出峰电位为-0.7 V(vsSCE),两者含量在5×10-4～1 mg/L和5×10-4～0.5 mg/L范围内峰电流和其含量呈良好的线性关系,检出限分别为2×10-4和4.3×10-3mg/L。     

辣根过氧化酶在磁性纳米修饰的离子注入电极上的电化学和电催化行为

辣根过氧化酶(HRP)在Co/NH2/ITO离子注入电极上有一对良好的氧化还原峰,峰电位分别为Epc=-0.2 V,Epa=-0.01 V(vsAg/AgCl)。该修饰电极对H2O2具有催化作用,可以用作H2O2的生物传感器,峰电流与H2O2的浓度分别在1.0×10-10~2.0×10-8mol/L和2.0×10-8~1.0×10-7mol/L范围内呈线性关系,线性回归方程分别为Ip(mA)=2.2986+0.06632c(nmol/L)和Ip(mA)=3.5788+7.3053E-4c(nmol/L),相关系数分别为0.9972和0.9688。检出限为1.0×10-10mol/L。     

对硫磷在纳米氧化铝薄膜修饰电极上的电化学行为及其测定

制备了纳米氧化铝修饰玻碳电极(nano-Al2O3/GCE/CME),用循环伏安法(CV)、线性扫描伏安法(LSV)研究了对硫磷(TP)在nano-Al2O3/GCE/CME上的电化学行为.实验表明,该修饰电极与裸电极相比能显著提高TP的氧化还原峰电流并降低其氧化峰电位.在0.1 mol/L HAc-NaAc缓冲溶液(pH =5)中,TP在该修饰电极上产生1个不可逆的还原峰( Epc1=-0.567 V)和1对可逆氧化还原峰( Epa2=0.018 V和Epc2=-0.008 V) ,氧化峰电流与TP的浓度在2.5×10-9～1.0×10-7 mol/L和1.0×10-7～1.0×10-5 mol/L范围内具有良好的线性关系,回归方程分别为: ip(μA)=0.2529+4.201C(μmol/L), r=0.9984和ip(μA)=0.6752+0.3181C(μmol/L), r=0.9946.开路富集30 s后,检出限为1.0 ×10-9 mol/L(S/N=3).在1.0×10-5 mol/L TP试液中连续测定10次,其RSD为3.8%.用此方法测定了蔬菜中TP的含量,回收率为95. 6%～100.5% ,结果满意.     

镍(Ⅱ)-玫瑰红酸钠修饰碳糊电极对丹宁酸的电催化氧化及应用

通过电化学方法使玫瑰红酸(Rh)与镍(Ⅱ)[Ni(Ⅱ)]生成Ni(Ⅱ)-Rh配合物,并聚合、沉积于碳糊电极(CPE)表面,制成Ni(Ⅱ)-Rh修饰的CPE电极[记为Ni(Ⅱ)-Rh-CPE]。试验表明:丹宁酸在此修饰电极上产生电催化氧化反应,在0.1mol·L~(-1)氢氧化钠溶液中,在电位0.2~0.6V范围内,扫描速率为0.1V·s-1的条件下进行伏安测定,丹宁酸的浓度在0.2~1.0μmol·L~(-1)和1.0~50.0μmol·L~(-1)两个区间与其阳极峰电流间呈线性关系,检出限(3S/N)为0.14μmol·L~(-1)。以自来水和河水作基体,用标准加入法对方法的回收率进行试验,测得回收率在95.2%~104%之间。     

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%.     

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.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.