共振瑞利散射光谱法测定长春瑞滨

提出了测定痕量长春瑞滨(NVB)的共振瑞利散射(RRS)光谱法。在pH为2.2的BR缓冲体系中,NVB与曙红Y(EY)形成物质的量的比为1比1的离子缔合物,从而引起共振瑞利散射强度显著增强,其最大散射波长位于312nm。散射信号的增强(ΔIRRS)与NVB的质量浓度在0.06~3.0mg·L-1范围内呈线性关系,检出限(3σ)为1.7μg·L-1。方法应用于注射液和尿样中NVB的测定,加标回收率在99.8%~101%之间,测定值的相对标准偏差(n=5)在1.1%~2.2%之间。     

镍(Ⅱ)-1-(1吡啶偶氮)-2-萘酚-十二烷基苯磺酸钠体系共振光散射法测定痕量镍

在pH 8.0的Tris-盐酸缓冲介质中,利用十二烷基苯磺酸钠(SDBS)增敏镍(Ⅱ)和1-(2-吡啶偶氮)-2-萘酚(PAN)形成离子缔合物体系,使体系共振光散射增强.体系最大散射波长545 nm,在15～500μg·L-1范围内共振散射增强强度(△I)与镍(Ⅱ)质量浓度呈线性关系.检出限(3S/N)为4.57μg·L-1,分别对50,200,400 μg·L-1镍(Ⅱ)标准溶液进行11次平行测定,测定值的相对标准偏差(n=6)依次为3.5%,3.0%,1.7%.据此提出了一种简单而快速的测定镍的方法.应用于测定水样中镍量,测得其平均回收率为98.5%.     

溴代十六烷基吡啶增敏共振光散射法测定乌拉地尔

以稀盐酸介质,固绿FCF作探针,表面活性剂溴代十六烷基吡啶作增敏剂,建立了测定乌拉地尔的共振光散射新方法。在稀盐酸存在下,乌拉地尔与固绿FCF-溴代十六烷基吡啶反应生成离子缔合物,使体系的共振光散射信号明显增强并产生新的共振光散射光谱,最大共振光散射(RLS)峰位于344 nm,乌拉地尔的质量浓度在0. 003～0. 28mg·L-1范围内与体系的共振光散射增强强度(ΔIRLS)呈线性关系,检出限为0. 0028 mg·L-1,加标回收率为98. 96%～101. 3%,相对标准偏差(RSD)(n=5)为2. 1%～2. 6%。该法灵敏、快速,用于市售乌拉地尔药物中乌拉地尔的测定,结果满意。     

免疫共振散射光谱法测定痕量人血清前白蛋白

在pH 7.6的磷酸氢二钠-磷酸二氢钠缓冲溶液中,羊抗人前白蛋白与前白蛋白发生特异性结合生成免疫复合物,导致体系的共振散射增强。体系在最大散射波长470 nm处,前白蛋白的质量浓度在0.067~2.82 mg.L-1范围内与共振散射增强强度(ΔI)呈线性关系,检出限(3S/N)为0.028 mg.L-1。应用于测定人血清前白蛋白,测定值相对标准偏差(n=6)在1.15%~3.00%之间。     

十二烷基苯磺酸钠增敏乙基紫共振光散射法测定人尿中痕量1-羟基芘

基于乙基紫(EV)与1-羟基芘(1-OHP)反应形成离子缔合物,导致体系的共振光散射(RLS)增强,建立了测定1-OHP的共振光散射法.在pH 8.0Tris-HCl缓冲介质中,最大RLS峰位于396 nm,其强度与1-OHP浓度成线性关系.加入表面活性剂十二烷基苯磺酸钠(SDBS),体系的灵敏度可提高两倍以上.方法的线性范围为4.0～982 μg·L-1,相关系数r=0.999 4,检出限1.2 μg·L-1,相对标准偏差为5.8%～7.9%,平均回收率为94%(n=6).已成功用于人尿中痕量1-OHP的测定,结果满意.     

罗丹明S与热变性DNA作用的共振光散射光谱研究及其应用

研究了小分子染料罗丹明S与热变性脱氧核糖核酸(DNA)在弱酸性条件下共振光散射光谱的特征.考察了各种影响因素,在优化条件下确立了共振光散射强度与鱼精DNA和小牛胸腺DNA浓度之间的线性关系,相应的线性范围分别为0.024～3.00,0.018～3.50 mg·L-1;相关系数为0.998 6,0.999 0;检出限为24.0,18.3μg·L-1;基于共振光散射的增强,建立了一种测定DNA的方法.     

盐酸吖啶黄-脱氧核糖核酸反应体系的共振瑞利散射及其应用

研究了盐酸吖啶黄与脱氧核糖核酸(DNA)之间的共振瑞利散射(RRS)增强作用,提出了共振瑞利散射技术测定核酸的方法。在pH 6.4的B-R缓冲溶液中,盐酸吖啶黄与脱氧核糖核酸结合使溶液共振瑞利散射强度增强,其最大散射峰位于505 nm处,而在330 nm波长处有一稍弱的散射峰。DNA质量浓度在0.04~0.80 mg.L-1范围内,与RRS强度呈线性关系,检出限(3S/N)为0.023 mg.L-1。应用于测定合成样品中DNA含量并测得回收率为98.0%~104.0%。初步探讨了反应机理,盐酸吖啶黄与DNA间的相互作用包含有静电引力、π-π堆积力。     

碘化物-CTMAB体系共振光散射法测定铋

用简易荧光计研究了在微酸性介质中,铋-碘化钾-十六烷基三甲基溴化铵(CTMAB)体系的共振光散射光谱,考查了光谱特征、影响因素和适宜的反应条件;确定了散射光强度与溶液中铋浓度的关系,提出了共振光散射法测定铋的方法;该法在室温下进行,线性范围为 0.2～0.6 mg·L-1,方法的检出限 0.003 mg·L-1;用于胃药中铋的测定,并在此样品的基础上加入铋(Ⅲ)标准进行了回收试验,得回收率结果为 107.3%.     

罗丹明B共振光散射法测定阴离子表面活性剂

在B-R缓冲溶液中,基于罗丹明B与阴离子表面活性剂(ASF)产生强烈共振光散射增强效应,建立了一种测定阴离子表面活性剂(SDS和SDBS)的方法。试验发现对于SDS和SDBS,最大共振光散射峰位于518和373 nm处。方法具有高的灵敏度,检出限分别为0.023 mg.L-1(SDS)和0.038 mg.L-1(SDBS),用于合成样和环境水样中阴离子表面活性剂含量的测定,回收率为94.0%~105.0%之间,并与亚甲蓝光度法相比,结果满意,可用于环境水样中阴离子表面活性剂的测定。     

酸性品红共振光散射法测定食品中的锌

建立了测定面制食品中锌的酸性品红共振光散射方法,研究了共振光散射的光谱特征及适宜的反应条件。在pH 6.88的Tris-盐酸缓冲介质及表面活性剂溴代十六烷基吡啶(TPB)存在下,Zn(Ⅱ)能够与酸性品红-TPB结合生成三元复合物,使共振光散射(RLS)显著增强并产生新的共振散射光谱,在最大散射峰379 nm处,体系的共振光散射增强程度(△IRLS)与0.008~0.25 mg·L~(-1)范围内的Zn(Ⅱ)呈线性关系,定量限为0.028 mg/100 g。方法简便、灵敏,加标回收率为98.9%~102%,相对标准偏差(RSD)(n=6)为2.0%~2.2%。方法用于面制食品中Zn的测定,结果满意。     

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.     

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.     

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.     

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.