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以4-磺酸钾邻苯二腈为原料合成了水溶性四磺酸酞菁(H2PcTS)及其金属配合物(ZnPcTS, FePcTS, CoPcTS), 通过透析法提纯得到了纯度较高的产物. 采用傅里叶变换红外光谱(FTIR)、紫外-可见吸收光谱(UV-Vis)、核磁共振氢谱(1H NMR)及循环伏安(CV)等测试手段表征了四磺酸酞菁及其配合物的结构和性质. 结果表明, 磺酸酞菁在水溶液中存在不同程度的聚集现象, 金属离子的配位会对磺酸酞菁的光谱和电化学性质产生影响. 研究了磺酸酞菁作为光敏剂催化氧化1,5-萘二酚的反应, 发现FePcTS/H2O2催化体系对1,5-萘二酚具有良好的催化氧化性能, 氧化产物主要为5-羟基-1,4-萘醌. 比较了不同溶液pH值对FePcTS和H2PcTS催化能力的影响, 初步探讨了该反应的催化机理. 相似文献
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以芳香醛和酮为原料,合成了3类姜黄素类1,5-二芳基-1,4-戊二烯-3-酮衍生物:1,5-二噻吩基-1,4-戊二烯-3-酮(Ⅰ)、1,5-二苯基-1,4-戊二烯-3-酮类(Ⅱ)和1,5-二呋喃基-1,4-戊二烯-3-酮(Ⅲ);利用元素分析、红外光谱、核磁共振谱(1 H NMR及13 C NMR)分析了产物的组成和结构,初步探讨了其反应条件和反应机理.结果表明,以无水乙醇为溶剂、8%的NaOH溶液为催化剂,反应温度为3050℃时,反应产率较高. 相似文献
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电化学还原合成1,5-二氨基萘 总被引:3,自引:0,他引:3
研究了以1,5-二硝基萘为原料电化学还原合成1,5-二氨基萘的反应. 室温下, 运用循环伏安法研究了1,5-二硝基萘的循环伏安行为, 1,5-二硝基萘的还原是一受扩散控制的不可逆反应; 循环伏安图上两个连续的还原峰对应于两个硝基的还原; 求出了反应的传递系数α1在0.275~0.335之间, α2在0.360~0.437之间. 探讨了电解电位(E)、底物浓度(c1)、电解电量(Q)、硫酸浓度(c2)以及溶剂(DMF)与水的体积比(Y)对产物产率的影响, 在最优条件下1,5-二氨基萘的产率最高可达77%. 相似文献
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以乙二醛、甲基肼和盐酸羟胺为起始原料,经缩合、肟化得到中间体肟基甲腙;该中间体不经分离直接加入到硫酸铜-吡啶-水体系中,经缩合环化得到2-甲基三唑-1-氧化物(MTO);随后用混酸(硝酸+硫酸)硝化得到目标产物2-甲基-4,5-二硝基三唑-1-氧化物(DNMTO);初步探讨了环化反应的机理,研究了反应温度与时间等因素对硝化反应的影响,确定了最佳硝化反应条件.与此同时,利用红外光谱、核磁共振、质谱及元素分析等分析了中间产物和DNMTO的组成和结构.结果表明,目标产物的总收率为16%,纯度为99%;最佳硝化反应温度为100℃,最佳硝化反应时间为0.5h. 相似文献
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The mechanism of cycloaddition reaction between singlet silylene carbene and acetone has been investigated with CCSD(T)//MP2/6-31G method. From the potential energy profile, it can be predicted that the reaction has two competitive dominant reaction pathways. One consists of two steps: (1) the two reactants (R1, R2) firstly form a four-membered ring intermediate (INT4) through a barrier-free exothermic reaction of 585.9 kJ/mol; (2) Then intermediate (INT4) isomerizes to CH3-transfer product (P4.1) via a transition state (TS4.1) with energy barrier of 5.3 kJ/mol. The other is as follows: on the basis of intermediate (INT4) created between R1 and R2, intermediate (INT4) further reacts with acetone (R2) to form the intermediate (INT5) through a barrier-free exothermic reaction of 166.3 kJ/mol; Then, intermediate (INT5) isomerizes to a silicic bis-heterocyclic product (P5) via a transition state (TS5), for which the barrier is 54.9 kJ/mol. The presented rule of this reaction: the [2+2] cycloaddition effect between the π orbital of silylene carbene and the π orbital of π-bonded compounds leads to the formation of a four-membered ring intermediate (INT4); The unsaturated property of C atom from carbene in the four-membered ring intermediate (INT4) results in the generation of CH3-transfer product (P4.1) and silicic bis-heterocyclic compound (P5). 相似文献
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Yuusaku Yokoyama Masamichi Nakakoshi Hiroaki Okuno Yohko Sakamoto Satoshi Sakurai 《Magnetic resonance in chemistry : MRC》2010,48(10):811-817
The reaction mechanism for the biomimetic synthesis of tryptophan from indole and serine in the presence of Ac2O in AcOH was investigated. Although the time‐course 1H‐NMR spectra of the reaction of 5‐methoxyindole with N‐acetylserine were measured in the presence of (CD3CO)2O in CD3CO2D, the reactive intermediate could not be detected. This reaction was conducted without 5‐methoxyindole in order to elucidate the reactive intermediate, but the intermediate could not be isolated from the reaction mixture. Since the intermediate would be expected to have a very short life time, and therefore be very difficult to detect by conventional analytical methods, the structure of the intermediate was elucidated using a 2D‐NMR technique, diffusion‐ordered spectroscopy (DOSY). Two intermediates were detected and confirmed to be 2‐methyl‐4‐methyleneoxazol‐5(4H)‐one and 2‐methyl‐4‐hydroxymethyloxazol‐5(4H)‐one. The present results demonstrated that DOSY is a powerful tool for the detection of unstable intermediates. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Wang YT Jin KJ Leopold SH Wang J Peng HL Platz MS Xue J Phillips DL Glover SA Novak M 《Journal of the American Chemical Society》2008,130(47):16021-16030
Aryloxenium ions 1 are reactive intermediates that are isoelectronic with the better known arylcarbenium and arylnitrenium ions. They are proposed to be involved in synthetically and industrially useful oxidation reactions of phenols. However, mechanistic studies of these intermediates are limited. Until recently, the lifetimes of these intermediates in solution and their reactivity patterns were unknown. Previously, the quinol esters 2 have been used to generate 1, which were indirectly detected by azide ion trapping to generate azide adducts 4 at the expense of quinols 3, during hydrolysis reactions in the dark. Laser flash photolysis (LFP) of 2b in the presence of O(2) in aqueous solution leads to two reactive intermediates with lambda(max) 360 and 460 nm, respectively, while in pure CH(3)CN only one species with lambda(max) 350 nm is produced. The intermediate with lambda(max) 460 nm was previously identified as 1b based on direct observation of its decomposition kinetics in the presence of N(3)(-), comparison to azide ion trapping results from the hydrolysis reactions, and photolysis reaction products (3b). The agreement between the calculated (B3LYP/6-31G(d)) and observed time-resolved resonance Raman (TR(3)) spectra of 1b further confirms its identity. The second intermediate with lambda(max) 360 nm (350 nm in CH(3)CN) has been characterized as the radical 5b, based on its photolytic generation in the less polar CH(3)CN and on isolated photolysis reaction products (6b and 7b). Only the radical intermediate 5b is generated by photolysis in CH(3)CN, so its UV-vis spectrum, reaction products, and decay kinetics can be investigated in this solvent without interference from 1b. In addition, the radical 5a was generated by LFP of 2a and was identified by comparison to a published UV-vis spectrum of authentic 5a obtained under similar conditions. The similarity of the UV-vis spectra of 5a and 5b, their reaction products, and the kinetics of their decay confirm the assigned structures. The lifetime of 1b in aqueous solution at room temperature is 170 ns. This intermediate decays with first-order kinetics. The radical intermediate 5b decomposes in a biphasic manner, with lifetimes of 12 and 75 mus. The decay processes of 5a and 5b were successfully modeled with a kinetic scheme that included reversible formation of a dimer. The scheme is similar to the kinetic models applied to describe the decay of other aryloxy radicals. 相似文献
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新型杂环三氮烯荧光试剂1,8-双(2-苯并噻唑重氮氨基)萘的合成及其分析应用 总被引:1,自引:1,他引:0
将1,8-萘二胺和苯并噻唑类试剂结合, 并引入杂环三氮烯结构, 合成了新荧光试剂1,8-双(2-苯并噻唑重氮氨基)萘(BBTANP), 其结构经红外光谱、核磁共振谱和元素分析证实. 研究结果表明, 在碱性介质中, 该试剂与Cu(Ⅱ)形成1∶1的络合物, 并在λex/λem=362 nm/459 nm处产生荧光增强作用. 据此建立了BBTANP测定Cu(Ⅱ)的新型荧光分析法, 该方法的线性范围为8.0×10-7—1.0×10-5 mol /L, 检测限为1.3×10-7 mol/L. 将其应用于水样中Cu(Ⅱ)的测定, 结果令人满意. 相似文献
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Xiuhui Lu Zhenxia Lian Pingping Xiang Yongqing Li 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(1):76-83
The mechanism of the cycloaddition reaction between singlet dichlorosilylene carbene (Cl2Si=C:) and formaldehyde has been investigated with MP2/6-31G* method, including geometry optimization and vibrational analysis
for the involved stationary points on the potential energy surface. The energies of the different conformations are calculated
by Zero-point energy and CCSD (T)//MP2/6-31G* method. From the potential energy profile, it can be predicted that the reaction
has two competitive dominant reaction pathways. The first dominant reaction pathway consists of two steps: (1) the two reactants
(R1, R2) firstly form a four-membered ring intermediate (INT4) through a barrier-free exothermic reaction of 387.9 kJ/mol;
(2) intermediate (INT4) then isomerizes to H-transfer product (P4.2) via a transition state (TS4.2) with energy barrier of
4.7 kJ/mol. The second dominant reaction pathway as follows: on the basis of intermediate (INT4) created between R1 and R2,
intermediate (INT4) further reacts with formaldehyde (R2) to form the intermediate (INT5) through a barrier-free exothermic
reaction of 158.3 kJ/mol. Then, intermediate (INT5) isomerizes to a silicic bis-heterocyclic product (P5) via a transition
state (TS5), for which the barrier is 40.1 kJ/mol. 相似文献
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TEA法测定NO2的反应机理研究 总被引:4,自引:0,他引:4
应用FABMS、NMR、IR、HPLC和紫外吸收光谱研究了室温下三乙醇胺与较高浓度NO2(2.48%)的反应情况,证明反应产物为三乙醇胺硝酸盐和三乙醇胺亚硝酸盐,提出了可能的反应机理,为TEA法监测空气中NO2的浓度提供了依据. 相似文献
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The reaction of O2 with HOCO has been studied by using an ab initio direct dynamics method based on the UB3PW91 density functional theory. Results show that the reaction can occur via two mechanisms: direct hydrogen abstraction and an addition reaction through a short-lived HOC(O)O2 intermediate. The lifetime of the intermediate is predicted to be 660 +/- 30 fs. Although it is an activated reaction, the activation energy is only 0.71 kcal/mol. At room temperature, the obtained thermal rate coefficient is 2.1 x 10(-12) cm3 molecule(-1) s(-1), which is in good agreement with the experimental results. 相似文献
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The kinetics of the reaction of H2O2 with excess SCN- in acidic media was studied by use of Ti(IV) as an indicator for the concentration of H2O2. Pseudo-first-order behavior was realized by this method, and these data confirm the acid-catalyzed rate law and rate constant reported some 40 years ago for this reaction under conditions of excess H2O2. Under the same conditions except without Ti(IV), repetitive-scan spectra reveal the formation and decay of an intermediate that absorbs in the UV. In the proposed mechanism, HOSCN is produced in the first step and it is converted rapidly to (SCN)2 through its equilibrium reaction with SCN-. The observed intermediate is believed to be (SCN)2, which decays on a longer time scale. Excellent global fits of this mechanism to the repetitive-scan data are obtained with rate constants constrained by the Ti(IV) data and published previously in our study of the ClO2/SCN- reaction. These fits yield a spectrum for (SCN)2 that is characterized by lambda(max) = 297 nm and epsilon297 = 147 M(-1) cm(-1), in fine agreement with our prior report. 相似文献
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Gonzalez JC Daier V Garcia S Goodman BA Atria AM Sala LF Signorella S 《Dalton transactions (Cambridge, England : 2003)》2004,(15):2288-2296
The oxidation of d-galacturonic acid by Cr(VI) yields the aldaric acid and Cr(III) as final products when a 30-times or higher excess of the uronic acid over Cr(VI) is used. The redox reaction involves the formation of intermediate Cr(IV) and Cr(V) species, with Cr(VI) and the two intermediate species reacting with galacturonic acid at comparable rates. The rate of disappearance of Cr(VI), Cr(IV) and Cr(V) depends on pH and [substrate], and the slow reaction step of the Cr(VI) to Cr(III) conversion depends on the reaction conditions. The EPR spectra show that five-coordinate oxo-Cr(V) bischelates are formed at pH < or = 5 with the uronic acid bound to Cr(V) through the carboxylate and the alpha-OH group of the furanose form or the ring oxygen of the pyranose form. Six-coordinated oxo-Cr(V) monochelates are observed as minor species in addition to the major five-coordinated oxo-Cr(V) bischelates only for galacturonic acid : Cr(VI) < or =10 : 1, in 0.25-0.50 M HClO(4). At pH 7.5 the EPR spectra show the formation of a Cr(V) complex where the vic-diol groups of Galur participate in the bonding to Cr(V). At pH 3-5 the Galur-Cr(V) species grow and decay over short periods in a similar way to that observed for [Cr(O)(alpha-hydroxy acid)(2)](-). The lack of chelation at any vic-diolate group of Galur when pH < or = 5 differentiates its ability to stabilise Cr(V) from that of neutral saccharides that form very stable oxo-Cr(V)(diolato)(2) species at pH > 1. 相似文献