预衍生化-共振散射光谱法测定4-壬基酚

通过衍生反应,建立了用共振散射光谱法测定4-壬基酚的方法.在碳酸钠介质中,痕量4-壬基酚与丹酰氯反应,产物在300～600 nm波长范围有很强的共振散射光.在选定的测定波长396.8 nm处,共振光散射强度的改变值与4-壬基酚质量浓度在6.20×10-4～6.00×10-2mg·L-1范围内呈线性关系.方法检出限为0.20μg·L-1.结合C18柱固相萃取分离,应用于环境水样和合成水样中4-壬基酚的测定,样品加标回收率为91.25%～94.50%,相对标准偏差小于4.0%.     

2-氨-6-氯嘌呤用于亚硝酸根离子的荧光光度法测定

应用荧光光谱法研究了2-氨-6-氯嘌呤与亚硝酸根离子间的相互作用并建立了亚硝酸根离子测定的新方法.在0.25 mol/L的H2SO4水溶液中,2-氨-6-氯嘌呤分子上的氨基与亚硝酸根离子发生重氮化反应生成重氮盐,重氮盐在沸水浴中加热水解,氨基被羟基取代,产生弱荧光的2-羟基-6-氯嘌呤.此反应导致荧光强度降低且在一定范围内与亚硝酸根离子浓度呈良好的线性关系,据此建立了荧光猝灭法测定亚硝酸根离子的新方法,其线性范围为1.00×10-7 ～1.30×10-5 mol/L,方法检出限为7.54×10-8 mol/L.该方法应用于自来水中亚硝酸根离子的测定,回收率为102% ～110%.     

离子色谱分离-亚铁氰化钾-钙黄绿素偶合化学发光测定NO_2~-

利用NO2-在酸性介质中氧化亚铁氰化钾为铁氰化钾,然后在碱性条件下和钙黄绿素化学发光反应相偶合,结合离子色谱分离和流动注射技术间接测定了NO2-。结果发现当钙黄绿素浓度为1.0×10-4mol/L,亚铁氰化钾浓度为2.0×10-4mol/L时,NO2-在1.0×10-5～1.0×10-7g/L范围内,化学发光强度与NO2-浓度成良好的线性关系(R=0.9958),检出限(3σ)为5.1×10-8g/L,对质量浓度为1.0×10-6g/LNO2-溶液进行11次平行测定,相对标准偏差为1.4%。将该方法用于蒸馏水和自来水中NO2-的测定,加标回收率分别为94.2%和107.1%。     

重氮-偶联反应间接光度法测定药物中美司钠

基于在H_2SO_4介质中,利用IO_3~-氧化美司钠后剩余的IO_3~-紧接着氧化盐酸羟胺产生NO_2~-,新生的NO_2~-使对氨基苯磺酸发生重氮化反应,生成对氨基苯磺酸重氮盐,该重氮盐再与盐酸萘乙二胺反应生成紫红色的偶氮染料,提出了利用重氮化-偶联反应间接分光光度测定美司钠含量的方法。方法中反应产物是一种有机偶氮染料,其最大吸收波长在522 nm处,工作曲线的线性范围在1.0~12 mg/L,摩尔吸光系数为1.296×10~5L·mol~(-1)·cm~(-1)。考察了各试剂用量对产物的影响,找出了该方法的最佳反应条件。用所建立的重氮化-偶联反应间接光度法测定了注射剂中美司钠的含量,方法的回收率在99.3%~101.2%之间,样品测定的相对标准偏差为0.82%和0.54%。     

三聚氰胺-1,4-环己烷二甲酸结合物微粒体系的共振散射光谱研究及其分析应用

在pH 3.6的乙酸盐缓冲溶液中和聚乙烯醇(PVA)存在下,三聚氰胺(MA)与1,4-环己烷二甲酸(CHDA)发生结合反应形成结合物微粒,该结合物微粒在480 nm处有一个较强的共振散射峰。三聚氰胺质量浓度在0.67～20.0μg/mL范围内与480 nm处的共振散射光强度呈线性关系,其检出限为12μg/L。研究了共存物质对CHDA共振散射测定三聚氰胺的影响,方法的选择性比较好,应用于合成废水测定,测定结果的相对标准偏差为2.3%～3.7%(n=5),回收率在94.8%～103.8%之间。     

溴代十四烷基吡啶共振散射光谱法测定痕量过氧化氢

基于辣根过氧化物酶催化H2O2氧化过量KI生成I3-,I3-与溴代十四烷基吡啶形成的缔合微粒在478 nm产生共振光散射峰,建立了一种测定痕量H2O2的共振散射光谱法.在选定条件下,478 nm处的共振光散射强度△I478nm与H2O2浓度在2.67×10-8～1.73×10-5 mol/L内呈良好的线性关系,其回归方程为△I478nm=2.54×107c-3.81,检出限为2.67×10-8 mol/L.该方法已用水样的测定,回收率在97.2%～105.2%之间.     

利用偶联反应光度法测定羟胺体系的研究及其应用

利用羟胺与碘反应生成亚硝酸,然后与对氨基苯磺酸发生重氮化反应,再与α-萘胺偶联形成偶氮化合物,从而建立了测定羟胺的新光度法.方法线性范围为2.0×10-6～1.5×10-5 mol/L,表观摩尔吸光系数为3.1×104 L.mol-1.cm-1,应用于水中羟胺和试剂丁二酮肟含量的测定,结果满意.     

顺序注射停留分光光度法测定磺胺乙酰钠

在HCl浓度为5.0×10-4mol/L时,磺胺乙酰钠-NaNO2-1-萘胺的重氮化偶合反应,生成不稳定的红色产物,利用顺序注射停留技术在473nm波长处检测该不稳定产物,建立了快速自动测定磺胺乙酰钠的新方法。该方法线性范围为5～2500μg/mL,检出限为0.018μg/mL,进样频率为62个/h。应用于药物中磺胺乙酰钠的测定,并与药典规定方法进行对照。     

结晶紫的酶催化共振散射光谱法测定痕量过氧化氢

在pH4.7的HAc-NaAc缓冲溶液中,牛血红蛋白可催化H2O2氧化I-生成I2,I2与过量的I-生成的I3-与带正电荷的结晶紫(CV+)可形成缔合物微粒,导致体系的共振散射光强度增强。在659 nm处,H2O2在2.065×10-7～1.652×10-6mol/L范围内与共振散射光强度的增加值(ΔI)呈良好的线性关系,相关系数r为0.9989,检出限为2.676×10-9mol/L。据此,建立了检测痕量H2O2的共振散射光谱新方法,该方法已用于水样中H2O2含量的测定。     

1,2-萘醌-4-磺酸钠体系分光光度法测定对苯二酚

建立了用1,2-萘醌-4-磺酸钠分光光度法测定对苯二酚的新方法. 研究表明,在pH=13.00的KCl-NaOH缓冲溶液中,对苯二酚能够催化溶液中的OH-离子与1,2-萘醌-4-磺酸钠反应形成橙红色的2-羟基-1,4-萘醌,其最大吸收波长为454 nm. 对苯二酚质量浓度在1.3×10-7～1.32×10-5 g/mL范围内与吸光度呈现良好的线性关系. 线性回归方程为A=0.025 61+0.073 28c(1×105 mol/L),线性相关系数r=0.995 5,检测限为9×10-8 g/mL. 方法能直接用于水样中对苯二酚含量的测定,回收率在96.5%～103%.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.