表面活性剂增敏光度法测定海产品中的微量镉(Ⅱ)

在六次甲基四胺缓冲溶液(pH=6.3)存在下,以二甲酚橙(XO)作显色剂,表面活性剂十六烷基三甲基溴化铵(CTMAB)对镉(Ⅱ)与XO的显色反应具有增敏作用,形成的镉(Ⅱ)-XO-CTMAB三元配合物呈紫色,配合物的最大吸收波长为605nm,表观摩尔吸光系数为2.04×10~5 L/(mol.cm)。镉(Ⅱ)的浓度在0～8μg(25mL)内符合比耳定律,线性回归方程为A=0.025c+0.2,检出限为5×10~(-4)μg/mL。该法用于海产品中微量镉的测定,测定结果的相对标准偏差为0.104％,回收率为91.0％。     

Fe(Ⅲ)-XO-OP胶束增敏光度法测定水中的痕量Fe(Ⅲ)

以HAc -NaAc为缓冲溶液 (pH =3.2 ) ,二甲酚橙与铁形成紫红色的配合物 ,最大吸收波长为 5 70nm ,在表面活性剂OP存在时 ,配合物的最大吸收波长红移至 5 90nm ,表观摩尔吸光系数由 3.0 4× 10 4L/ (mol·cm)增至 3.6 7×10 5L/ (mol·cm) ,铁的质量浓度在 0～ 2 0 .0 μg/ (2 5mL)内符合比耳定律。该法用于水样中微量铁的测定 ,铁的回收率为 99.8%～ 10 0 .2 % ,测定结果的相对标准偏差为 0 .16 0 %～ 0 .16 6 %。     

二甲酚橙-锆(Ⅳ)配合物光度法测定蛋白质

在酸性溶液中,蛋白质与二甲酚橙-锆(Ⅳ)配合物能够相互作用形成超分子复合物,其最大吸收波长较二甲酚橙-锆(Ⅳ)配合物红移了50 nm。在实验选定最佳条件下,600 nm波长处的吸光度与牛血清白蛋白(BSA)、人血清白蛋白(HAS)均在0.2~16μg/mL范围内呈线性关系,相对标准偏差为0.83%(n=7),检出限为0.1 mg/L。该法灵敏度高,选择性好,用于人血清总蛋白含量的测定,结果满意。     

示差法测定高含量铝

高含量铝的测定,一般使用容量法,但是操作较为繁杂,本文尝试改用示差法。我们研究了显色剂二甲酚橙与铝在不同pH条件下,不同试剂浓度,形成之络合物的吸收光谱,从而选出了最佳侧定波长λ=540nm。研究了络合     

双波长分光光度法测定青麻果实中锌含量

在pH=6.0的六亚甲基四胺缓冲溶液中,Zn~(2+)与二甲酚橙形成红色配合物,以试剂空白为参比,在570nm处褪色,在440nm处生色,实验表明在一定范围内△A=A440-A570与Zn~(2+)浓度呈线性,建立了双波长分光光度法测定青麻果实中Zn~(2+)含量的方法。最佳实验条件下,Zn~(2+)含量在0.1~0.6μg/mL范围内符合Lambert-Bill定律,检出限为1.5×10~(-2)μg/mL。结果表明,方法的相对标准偏差小于5%,加标回收率为95.0%~96.0%。方法简便快速。     

双波长分光光度法测定蒲公英中总黄酮

建立了测定蒲公英中总黄酮含量的双波长分光光度法。实验结果表明,以Al(NO3)3为显色剂,在测定波长为510nm,参比波长为590nm的条件下,总黄酮的质量浓度与吸光度差值△A在8.0~40.0μg/mL范围呈良好线性关系,相关系数r=0.9993,回收率为98.75%~102.30%,相对标准偏差(RSD)为1.24%。该方法操作简便,稳定可靠,重现性好。     

1,9-二甲基亚甲基蓝光度法测定海参糖胺聚糖

研究了1,9-二甲基亚甲蓝与海参糖胺聚糖反应体系。显色剂pH为3.00,最佳吸收波长为520nm,加入显色剂4～6min后测定吸光度,线性范围为5～30mg/L,线性回归方程:A=0.0104c 0.0118,r=0.9996(n=3)。结合木瓜蛋白酶酶解作用可以利用该法直接测定海参体壁中糖胺聚糖。     

新显色剂 1-[2,3,5-三氮唑偶氮]-2-萘酚的合成及其与钴(Ⅱ)的分光光度研究

合成了新显色剂 1-[2,3,5-三氮唑偶氮]-2-萘酚(简称TZAN ) ,并研究了其性质及与钴显色反应的条件,测定了试剂有关参数.在 pH 6.08 的 HAc-NaAc 介质中,试剂与钴形成红色络合物,其最大吸收波长为 578.2 nm,摩尔络合比 Co2+∶R=1∶2,用双波长测定,表观摩尔吸光系数为 3.15×104 L/mol.cm,钴量在 0～1.0 μg/mL 范围内遵守比耳定律.     

1-(4-硝基苯)-3-(3-甲基吡啶)-三氮烯的合成及其与锌的显色反应

报道了显色剂1-(4-硝基苯)-3-(3-甲基吡啶)-三氮烯的合成及其与锌的显色反应研究。在Triton X-100存在下,pH 11.0的硼砂-氢氧化钠缓冲溶液中,该试剂能与锌发生显色反应,锌与显色剂形成摩尔比为1∶4的黄色配合物,在445 nm波长处有最大正吸收峰,在535 nm波长处有最大负吸收。以445 nm为参比波长,535 nm为测量波长进行双波长测定,表观摩尔吸光系数为1.88×105L.mol-1.cm-1,锌浓度在0~12μg/25 mL范围内符合比耳定律。用拟定方法测定植物样品中微量锌,分析结果的相对标准偏差均小于2.5%,加标回收率在99.6%~100.4%之间。     

紫外分光光度法测定聚硫密封胶中二氧化钛

基于强酸性溶液中钛氧离子与H2O2发生显色络合反应的原理,建立了浓硫酸–硫酸铵消解–紫外分光光度法测定聚硫密封胶中TiO_2含量的方法。通过对酸液和显色剂用量,以及显色络合物稳定性的系统考察,确定浓硫酸用量为2 mL,双氧水用量为3 mL,检测波长为403 nm。二氧化钛质量浓度在0~130μg/mL范围内与其吸光度呈良好的线性关系,线性方程为A=5.047 8c–0.019 31,r~2=0.999 2,检出限为0.08μg/mL。检测结果的相对标准偏差为0.89%(n=5),3水平加标平均回收率为101.7%。该方法线性范围较宽、检出限低、重复性好,可用于聚硫密封胶中二氧化钛的定量分析。     

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%.     

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.     

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.     

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.     

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.     

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.     

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.