5-溴水杨基荧光酮-溴化十六烷基三甲基铵吸光光度法测定微量锗

研究了在表面活性剂CTMAB存在下锗与5-溴水杨基荧光酮形成配合物的显色反应,在2mol·L~(-1)H_2SO_4介质中测得配合物的表观摩尔吸光系数为1.62×10~5.锗量在0～8μg/25ml范围内符合比耳定律.该体系反应酸度高,选择性好.方法稳定、决速.已用于水相直接测定人参、当归、灵芝、枸杞子和竹沥汁等中药材中微量锗,结果满意     

基于水杨基荧光酮的催化动力学荧光熄灭测定痕量亚硝酸根

以溴酸钾与水杨基荧光酮的氧化-还原反应为指示反应,以水杨基荧光酮荧光变化为测定依据,系统研究了亚硝酸根催化荧光熄灭反应的动力学条件,建立了水杨基荧光酮催化动力学荧光熄灭法测定自来水中痕量亚硝酸根的方法。用固定时间法得到了良好的工作曲线lgF0／F= 1．305 c-0．017 5,线性范围为0．1～0．5μg／25 mL,线性相关系数为0．999 0。该方法的检出限为1．6μg·L-1。水样测定结果的相对标准偏差为3．7％,加标回收率为95％~106％。     

荧光酮取代基对碳纳米管协同增效作用的影响研究

以金属离子(Pb2+、Mn2+)与荧光酮(苯基荧光酮、水杨基荧光酮、邻氯苯基荧光酮)的显色体系为模型,在阳离子表面活性剂十六烷基三甲基溴化铵(CTMAB)的存在下,研究了显色剂荧光酮不同的取代基对碳纳米管协同增效作用的影响。结果表明,碳纳米管作为一种新型增效剂,与荧光酮产生π-π作用,使荧光酮类显色体系的灵敏度得到提高。3种荧光酮的增敏强度为ΔA苯基荧光酮ΔA水杨基荧光酮ΔA邻氯苯基荧光酮。该文从空间位阻、氢键以及取代基的电子效应等方面进行了机理的探讨。水杨基荧光酮和邻氯苯基荧光酮由于邻位取代基的存在,增加了荧光酮分子与碳纳米管之间π-π作用的空间位阻,导致显色体系的增敏强度较小;与带有—Cl吸电子基团的邻氯苯基荧光酮相比,水杨基荧光酮上的供电子基团—OH可与碳纳米管上的含氧基团形成氢键,由于氢键的作用以及电子效应的不同导致了增敏效应的差异。对体系的实验条件进行优化,得出最佳测锰体系的线性范围为0.04~0.56 mg/L,回归方程为A=0.016+1.541C(mg/L),表观摩尔吸光系数ε=9.45×104L/(mol.cm),r=0.997。利用该体系对自来水中的锰进行了测定,结果令人满意。     

汞(Ⅱ)-邻菲啰啉-水杨基荧光酮荧光猝灭体系的研究及应用

在pH 8.0～9.0的KH2PO4-Na2B4O7缓冲溶液中,在乳化剂OP存在下,溶液中的汞(Ⅱ)与邻菲啰啉(o-phen)和水杨基荧光酮(SAF)反应生成一多元配合物,使水杨基荧光酮溶液的荧光猝灭,据此建立了测定痕量汞的荧光分析法.体系的激发波长λex=365.0 nm,发射波长λem=580 nm.汞的浓度在0～80μg/L范围内与△F存在良好的线性关系.方法的检出限为1.04 ng/mL.对1μgHg(Ⅱ)进行11次平行测定,其相对标准偏差RSD=1.9%,配合物的组成比为Hg(Ⅱ)o-phenSAF=122.方法用于环境水样中痕量汞的测定.     

5′-硝基水杨基荧光酮分光光度法测定钼

研究了5′-硝基水杨基荧光酮分光光度测定钼的方法.在磷酸介质中,表面活性剂OP存在下,钼(Ⅵ)与5′-硝基水杨基荧光酮形成稳定的桔红色络合物,其最大吸收波长为528 nm,表现摩尔吸光率ε528=1.22×105L·mol-1·cm-1,钼的质量浓度在0.30 mg·L-1以内符合比耳定律.方法应用于不含钨、钛或其含量极低的碳钢及低合金钢中微量钼的测定,所得结果与标准值相符.     

阳离子表面活性剂存在下锗与2,3,7-三羟基-9-取代萤光酮显色反应的研究

本文研究了八种2,3,7-三羟基-9-取代荧光酮在阳离子表面活性剂存在下与锗的胶束增敏显色反应.发现水杨基萤光酮及邻硝基苯基萤光酮在强酸性介质中可以和溴化十六烷基三甲基铵形成高灵敏的胶束三元配合物.较详细地研究了用邻硝基苯基萤光酮与溴化十六烷基三甲基铵分光光度法测定微量锗的实验条件.并探讨了有关配合物的组成以及胶束增敏反应的机理.此法可不经分离,直接快速测定铅锌矿中的微量锗,结果比较满意.     

铁(Ⅲ)-过氧化氢-水杨基荧光酮-溴化十六烷基三甲铵荧光猝灭反应及其应用

在pH 3.1～5.2的HCl-NaAc缓冲介质中,溶液中的铁(Ⅲ)与过氧化氢(H2O2),水杨基荧光酮(SAF)和溴化十六烷基三甲铵(CTMAB)反应产生一多元混合络合物,使水杨基荧光酮溶液的荧光明显猝灭,据此建立了测定痕量铁的荧光猝灭分析法.该体系的激发波长λex=435.8 nm,发射波长λem=540 nm.铁的浓度在2～100 μg/L范围内有良好的线性关系;方法的检出限为0.41 μg/L.该方法灵敏度高,操作简便,用于天然水和人发样中微量铁的测定,结果满意.     

水杨基荧光酮-溴化十六烷基三甲基铵高灵敏分光光度法测定微量钛

在硫酸介质中,钛与水杨基荧光酮及CTMAB可以形成两种颜色不同的络合物。当水杨基荧光酮过量时,络合物呈红紫色(λmax=540nm);当钛过量时,络合物呈蓝紫色(λmax=610nm)。本文系统研究了红紫色络合物的生成条件及其在测定钛中的应用。试验证明,钛-水杨基荧光酮-CTMAB的红紫色络合物具有较高的灵敏度ε640=1.64*10~5. 常见阳离子中除钨(Ⅵ)以外,绝大部分阳离子均不干扰钛的测定或可用适当掩蔽剂消除干扰。有色溶液在钛含量为0—5生克/25毫升时,遵守比尔定律。本法可以不经任何分离,直接快速测定某些合金钢及纯金属材料(如铝)中的微量钛并得到了比较满意的结果。     

红霉素与水杨基荧光酮胶束增敏荷移反应光度分析

本文提出了一种基于胶束增敏荷移反应测定红霉素的光度分析法.研究了在阴离子表面活性剂十二烷基硫酸钠(SDS)胶束体系中红霉素作为电荷供体与电荷受体水杨基荧光酮(SAF)之间的荷移络合物的光谱性质.发现SDS对该体系有增敏作用(ε=3.95×104 L·mol-1·cm-1提高近3倍),红霉素浓度在0.73mg/L～51.4mg/L范围内符合比尔定律,r=0.9999.本方法用于片剂中红霉素含量的测定,回收率为99.7%,9次测定的相对标准偏差为0.24%.     

水杨基荧光酮胶束增敏流动注射分光光度法测定测量锗

本文将锗－水杨基荧光酮－溴化十六烷基三甲基铵胶束显色体系应用于流动注射分析，建立了测定微量锗的快速方法。方法采用单通道流路及合并带流路进行试验。对有关的管路参数及试剂浓度等影响因素进行了探讨。优化的流动注射分析体系对锗的检测灵敏度高、重现性好。方法用于混合成试样及有机锗生物制品中锗的测定，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.