高碘酸钾氧化酸性铬蓝K催化光度法测定痕量锰

研究了测定痕量锰的新催化光度法，在pH11.90的条件下，锰（Ⅱ）催化高碘酸钾氧化酸性铬蓝K的反应。测定锰的线性范围为0—8．0ng／mE，检出限为0．05ng／mL。用于饮用水中锰的测定，方法的回收率在94．3％-102．7％范围内，结果令人满意。     

催化过氧化氢氧化铬黑T褪色光度法测定痕量锰(Ⅱ)

在pH11.0的Na2B4O7-NaOH缓冲溶液中十二烷基磺酸钠（DBS）可增敏Mn(II）催化过氧化氢氧化铬黑T（EBT）的褪色反应，据此建立了催化褪色光度法测定痕量锰（Ⅱ）的新方法，锰（Ⅱ）浓度在5．0－12．0ug/L范围内服从比耳定律，回归方程ΔA=-0.014 0.32CMn(Ⅱ）（μg/L),r=0.9999检出限0．5ng/mL，应用该法测定人发和茶叶中的Mn(Ⅱ），测定结果满意。     

偶氮胂I-高碘酸钾催化光度法测定痕量Mn(Ⅱ)

研究了在HAc—NH4Ac介质中，以1，10-菲啰啉为活化剂，锰(Ⅱ)催化高碘酸钾氧化偶氮胂I褪色反应的条件及影响因素，建立了动力学光度法测定痕量Mn(Ⅱ)的新方法。方法线性范围为0-80μg/L，检出限为6．3ng/mL，对60μg/L,Mn(Ⅱ)测定的相对标准偏差为2．6％。导出了动力学方程，该催化反应的表观活化能为130．4kJ／mol。已用于野菜、水果样品中锰(Ⅱ)的测定。     

催化动力学荧光分析法测定痕量锰

在邻苯二甲酸氢钾-NaOH介质中,Mn（Ⅱ）催化H2O2氧化偶氮若丹宁类新荧光试剂3-（4′-硝基苯基）-5-（2′-胂酸基偶氮）若丹宁（4NRAAP）和3-（4′-甲氧基苯基）-5-（2′-胂酸基偶氮）若丹宁（4MORAAP）,其产物呈现新的强荧光峰,从而建立了若丹宁类试剂催化荧光法测定痕量Mn（Ⅱ）的新方法。其线性范围分别为0-0.012μg/mL,0~0.010μg/mL,检出限分别为9.0×10^-11g/mL,2.0×10^-11g/mL,是目前测定锰最灵敏的方法之一。     

催化动力学光度法测定痕量锰

在活化剂氨三乙酸存在下,基于锰(Ⅱ)催化高碘酸钾氧化亮绿SF的反应,建立了测定痕量锰(Ⅱ)的催化动力学光度法。在优化的实验条件下,测定锰(Ⅱ)的线性范围为0.6~6.0 ng/mL,检出限为6.0×10-11g/mL,相对标准偏差为2.5%(n=9)。该法灵敏度高,选择性和重现性较好,已用于测定饮用水和葡萄酒试样中的痕量锰。     

催化动力学光度法测定中成药中痕量锰(Ⅱ)

研究了Mn（Ⅱ）催化KIO4氧化二苯胺磺酸钠的显色反应。在HAc-NaAc介质中，以吐温-80作表面活性剂，测定波长为510nm，锰浓度在0-0.6μg/25mL范围内与吸光度呈线性关系.该法用于中成经增长乐中锰含量的测定,结果令人满意.     

催化动力学光度法测定水中微量锰

１引言研究了锰（Ⅱ）催化亮绿ＳＦ褪色反应的动力学特性。在ＮａＡｃ－ＨＡｃ介质中，锰（Ⅱ）对高碘酸钾氧化该试剂的褪色反应具有强烈催化作用，其褪色反应速率与锰（Ⅱ）的浓度在一定范围内呈良好的线性关系。详细研究了亮绿ＳＦ催化动力学光度法测定微量锰（Ⅱ）的条件，建立了测定微量锰（Ⅱ）的新方法。有关文献中催化动力学光度法测定锰（Ⅱ）的检出限大多为１０－１０ｇ／ｍＬ，本方法的检出限为６．０×１０－１１ｇ／ｍＬ，选择性较好，方法相对标准偏差２．５％，用于测定水样中的锰，结果满意。２实验部分２．１主要试剂和仪器…     

以N-十二烷基二甲基铵基乙酸为增敏剂催化光度法测定锰

基于存在增敏剂N-十二烷基二甲基铵基乙酸（DDMAA）和活化剂氨三乙酸,锰（Ⅱ）催化高碘酸钾氧化萘酚绿B的反应,拟定了测定痕量锰的新催化光度法。本法在两性表面活性剂DDMAA存在下,灵敏度提高10．3倍（Mn~(2+)量为0~6．0μg/L）和5．3倍（Mn~(2+)量为6．0~14μg/L）,相对标准偏差为0．5％,检出限为5．6×10~(-8)g/L,可用于酒样和谷物制品中锰的测定。     

用锰(Ⅱ)-氨三乙酸-溴代十六烷基三甲胺-高碘酸钾-灿烂甲酚蓝体系催化光度法测定锰

基于存在活化剂氨三乙酸和增敏剂溴代十六烷基三甲胺，锰（Ⅱ）催化高碘酸钾氧化灿烂甲酚蓝的反应，拟定了测定痕量锰的催化光度法，讨论了有关反应机理。本法由于添加了溴代十六烷基三甲胺，灵敏度揭高2．5倍，测定锰含量线性范围为8．0×10－4～8．0×10－3mg／L，检出限为7．0×10－5mg／L，相对标准偏差为4．7％（n＝11），可用于测定茶叶和水样中的锰。     

硫胺素-亚硝酸根体系的荧光性质研究及应用

研究了在碱性溶液中硫胺素（VB1）与亚硝酸根的荧光反应,建立了荧光光度法测定硫胺素的新方法。方法线性范围为1．28－324ng/mL,检出限0．52ng/mL,对15个浓度为100ng/mL的硫胺素溶液进行测定,相对标准偏差为1．4％。应用于药物中硫胺素的测定,回收率在96．5％－101．8％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%.     

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.     

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.     

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.     

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.