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金属胶束催化对硝基苯酚吡啶甲酸酯水解的动力学研究 总被引:1,自引:0,他引:1
合成了两种大环过渡金属配合物NiR和CuR(R表示高氯酸-5,7,7,12,14,14-六甲基-1,4,8,11-四氮杂环十四烷),将NiR和CuR分别与表面活性剂正月桂酸肌氨酸组成金属胶束,并以其为模拟水解金属酶用于催化对硝基苯酚吡啶甲酸酯(PNPP)水解.特征光谱分析表明,在催化PNPP水解过程中形成了由Ni(Ⅱ)或Cu(Ⅱ)配合物与PNPP组成的中间物种,并由此提出了催化PNPP水解的机理,建立了用于计算动力学常数的动力学模型. 相似文献
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A new catalytic system containing an unsaturated heterocyclic nitrogen ligand and lanthanum(III) was constructed and used as a catalyst in the hydrolysis of bis(4‐nitrophenyl) phosphate ester (BNPP) in this work. The results indicated that this catalytic system showed greater catalytic activity in the hydrolysis of BNPP and better reproducibility and stability than other similar lanthanum(III) systems. The catalytic rate of the BNPP hydrolysis was about 107‐fold faster than that of its spontaneous hydrolysis at the same conditions. Compared with the previous Cu(II) or Ni(II) complex containing the same ligand in the water, the activity of the macrocyclic La(III) complex increases ca. 103‐fold for BNPP catalytic hydrolysis. The experimental data showed that the monohydroxy complex made of the heterocyclic nitrogen ligand and lanthanum(III) is the real active species as a catalyst in BNPP catalytic hydrolysis. 相似文献
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E. P. Tishkova L. A. Kudryavtseva R. A. Shagidullina B. E. Ivanov 《Russian Chemical Bulletin》1994,43(9):1488-1492
The effect of dicationic surfactants on the hydrolysis of bis(4-nitrophenyl) ethyl phosphate in a borate buffer is studied. The presence of long-chain surfactants results in a significant (up to 50-fold) increase in the observed rate constant (k
obs) of the process. The catalytic effect of micelles increases with increasing alkyl chain length due to the strengthening of binding of the reagents by micelles. The presence of two cationic centers in the surfactant molecule enhances the catalytic properties of micelles. The dependence ofk
obs of hydrolysis of the substrate on the borate buffer concentration is studied. Alkaline hydrolysis is more sensitive to the added surfactant than the reaction involving borate ions.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1576–1580, September, 1994. 相似文献
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Min Li Ping Zhang Wei-Peng Zeng Ying Liu 《Journal of Dispersion Science and Technology》2013,34(8):1182-1187
A kind of new functional surfactant with substituted long alkyl pyridine was synthesized and its Ce(IV), Zn(II), and Cu(II) complexes were used as hydrolytic metalloenzyme models. The hydrolysis of p-nitrophenyl picolinate (PNPP) catalyzed by the metallomicelles in CTAB micellar solution was investigated at different pH and 30°C. Kinetic parameters of catalytic hydrolysis were obtained by employing the ternary complex kinetic model for metallomicellar catalysis. Effects of the structure of ligands and microenvironment of reaction on the hydrolytic reaction of PNPP have been discussed in detail. From the apparent rate constants (k obsd ) of the catalytic hydrolysis of PNPP, it can be seen that the catalytic effect of complexes of ligand L2 with long hydrocarbon chain was stronger than that of ligand L1, and complex CuL2 showed higher catalytic efficacy on the hydrolytic reaction than those of ZnL2 and CeL2. However, experiment results in this article showed that ZnL2 and CeL2 are more susceptible to environment than CuL2. The catalytic mechanism was proposed, and the possibly active species for the catalytic hydrolysis of PNPP was determined to be the hydroxylated metal complex. 相似文献
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Jia-qing Xie Fa-mei Feng Shen-xin Li Fuan Liu 《Journal of Dispersion Science and Technology》2013,34(9):1311-1318
The intramolecular nucleophilic substitution of an activated phosphate diester, bis(p-nitrophenyl) phosphate (BNPP) as the nucleic acids substitute, was investigated. A macro-cyclic ligand and the corresponding Cu (II) and Ni (II) complexes were synthesized and characterized. The metallomicelles made up of macrocyclic divalent metal complex and micelle, as mimic hydrolytic metalloenzyme, was used in BNPP catalytic hydrolysis. The metallomicelles displayed higher catalytic activity although they do not attain the catalytic efficiency of enzymes. The analysis of specific absorption spectra showed that the course of the BNPP catalytic reaction was different from that of the BNPP spontaneous hydrolysis, and was an intramolecular nucleophilic substitution reaction. Based on the analytic result of the specific absorption spectrum, an intramolecular nucleophilic substitution mechanism of BNPP catalytic hydrolysis was proposed and a correlative kinetic mathematical model was established, and the corresponding thermodynamic and kinetic constant was calculated. The result of this study proved validity of the mechanism and mathematical model proposed in the article. 相似文献
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A copper(Ⅱ) complex 1 of a novel macrocyclic polyamine ligand with hydroxylethyl pendant groups, 4,11-bis(hydroxylethyl)-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (L) has been synthesized and characterized. Rate enhancement for hydrolysis of p-nitrophenyl picolinate (PNPP) catalyzed by 1 was studied kinetically under Brij35 micellar condition. For comparision, the catalytic activity of corresponding copper(Ⅱ) complex 2 of non-substituted macrocyclic polyamine ligand, 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraaza-cyclotetradecane (L') toward the hydrolysis of PNPP was also investigated. The results indicate that the macrocyclic polyamine copper(Ⅱ) complex 1 effectively catalyzed the hydrolysis of PNPP, and the pendant ligand hydroxyl group or deprotonated pendant ligand hydroxyl group can act as catalytically active species in the reaction. A ternary Complex kinetic model involving metal ion, ligand and substrate has been proposed, and the results confirmed the reasonability of such kinetic model. 相似文献
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Dr. Marco Antônio G. B. Gomes Dr. Christiane Fernandes Dr. Lawrence R. Gahan Dr. Gerhard Schenk Dr. Adolfo Horn Jr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(3):877-887
Organophosphates are a class of organic compounds that are important for living organisms, forming the building blocks for DNA, RNA, and some essential cofactors. Furthermore, non-natural organophosphates are widely used in industrial applications, including as pesticides; in laundry detergents; and, unfortunately, as chemical weapons agents. In some cases, the natural degradation of organophosphates can take thousands of years; this longevity creates problems associated with handling and the storage of waste generated by such phosphate esters, in particular. Efforts to develop new catalysts for the cleavage of phosphate esters have progressed in recent decades, mainly in the area of homogeneous catalysis. In contrast, the development of heterogeneous catalysts for the hydrolysis of organophosphates has not been as prominent. Herein, examples of heterogeneous systems are described and the importance of the development of heterogeneous catalysts applicable to organophosphate hydrolysis is highlighted, shedding light on recent advances related to different solid matrices that have been employed. 相似文献
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Journal of Solution Chemistry - An aza-macrocyclic ligand, 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane-N/- acetic acid (L), was synthesized and characterized. The chemical... 相似文献
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The reactions of a homogeneous series of phenols with bis(4-nitrophenyl) carbonate (BNPC), bis(4-nitrophenyl) thionocarbonate (BNPTOC), and methyl 4-nitrophenyl thionocarbonate (MNPTOC) are subjected to a kinetic investigation in water, at 25.0 degrees C and ionic strength of 0.2 M (KCl). Under excess of phenol over the substrate, all the reactions obey pseudo-first-order kinetics and are first order in phenoxide anion. The reactions of BNPC show a linear Br?nsted-type plot with slope beta = 0.66, consistent with a concerted mechanism (one step). In contrast, those of BNPTOC and MNPTOC show biphasic Br?nsted-type plots with slopes beta = 0.30 and 0.44, respectively, at high pK(a), and beta = 1.25 and 1.60, respectively, at low pK(a), consistent with stepwise mechanisms. For the reactions of both thionocarbonates, the pK(a) value at the center of the Br?nsted plot (pK(a)(0)) is 7.1, which corresponds to the pK(a) of 4-nitrophenol. This confirms that the phenolyses of the thionocarbonates are stepwise processes, with the formation of an anionic tetrahedral intermediate. By the comparison of the kinetics and mechanisms of the title reactions with similar reactions, the following conclusions can be drawn: (i) Substitution of S(-) by O(-) in an anionic tetrahedral intermediate (T(-)) destabilizes it. (ii) The change of MeO by 4-nitrophenoxy in T(-) results in an increase of both the rate constant and equilibrium constant, for the formation of T(-), and also in an enlargement of the rate coefficient for the expulsion of 4-nitrophenoxide from T(-). (iii) Substitution of an amino group in a tetrahedral intermediate by ArO destabilizes it. (iv) Secondary alicyclic amines and other amines show greater reactivity toward MNPTOC than isobasic phenoxide anions. 相似文献
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The hydrolysis of bis-(nitrophenyl) phosphate (BNPP) as model for secondary phosphate esters is analyzed at six different concentrations of Eu(III) ions and four temperatures between 303 and 343 K. Eyring plots yield activation enthalpy parameters which with, e.g. [Eu 3+ ] between 0.40 and 10.0 mM drop from 130 to 74 kJ mol m 1 , respectively, with a relatively small drop in the opposing entropy contributions. The observed saturation profiles allow for the first time to evaluate the influence of j H and j S separately on the Michaelis-Menten values K M and k cat , showing that the catalytic metal-ion effects are largely due to changes in k cat and dominated by favorable j H changes. Preliminary studies of the solvent influence show a surprising difference between water mixtures with either ethanol or DMSO. With, e.g. 40% ethanol, one observes a doubling of the rate constant, with 40% DMSO an almost 10-fold rate decrease. In both cases, a linear correlation with the solvent polarity parameter E T is found. 相似文献
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异双核配合物金属胶束模拟磷酸酯酶催化磷酸单酯水解 总被引:1,自引:0,他引:1
合成和表征了四种含过渡金属离子Cu(Ⅱ)和Ni(Ⅱ)的草酰胺桥联异双核配合物,并将这些配合物与Brij35表面活性剂胶束构成金属胶束作为金属水解酶模拟物用于催化对硝基苯酚磷酸单酯(NPP)水解. 研究了金属胶束对NPP水解反应的催化机理,建立了异双核配合物催化NPP水解的动力学数学模型. 结果表明,四种草酰胺桥联异双核配合物在NPP水解反应中表现出较高的催化活性,随着胶束溶液pH的增大,配合物催化NPP水解的速率提高. 配合物中的两个金属离子在催化NPP水解过程中表现出较好的协同效应. 相似文献
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Yunus Bekdemir Bilge Eren Halil Kütük 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):689-696
Abstract The acid catalyzed hydrolyses of some cyclic disulfonimides, N-(4-substitutedphenyl)-o-benzenedisulfonimides (1a–d) have been studied in concentrated aqueous acidic solutions. Analysis of the data by the Excess Acidity Method, activation parameters, substituent, and solvent deuterium isotope effect are all indicate hydrolysis by an A-1 mechanism in the studied range. 相似文献
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Shu-lan Cai Fa-mei Feng Fu-an Liu 《Journal of Dispersion Science and Technology》2016,37(8):1170-1177
This study reports the synthesis method of a new aza-crown ether with an acetamide branch ligand, 2-(1,10-dioxa-4,7,13,16-tetraaza-cyclooctadec-4-yl)-acetamide (L), and determines the chemical composition of the cerium complex containing the aza-crown ether ligand by a new fluorescence spectrophotometric method. In the report, the cerium complex and its metallomicellar systems were used as catalysts in the hydrolysis of bis(4-nitrophenyl)phosphate ester (BNPP), and their catalytic activity was studied by the comparative method. The interaction between the metallomicelle and BNPP was proved by the fluorescence spectrum. The catalytic rate of BNPP hydrolysis was measured kinetically using the UV-Vis spectrophotometric method. The results indicated that the metallomicellar system of the anionic surfactant exhibited excellent catalytic function and relatively higher catalytic activity than that of the complex solution, the metallomicelle of nonionic and cationic surfactants, and the micelle provided an effective catalytic environment for the catalytic reaction. The experimental results also showed that the best acidity for the metallomicelle catalysis is pH 8.0, and the mono-hydroxy complex may be the real active species uaed as a catalyst in BNPP catalytic hydrolysis. The reaction mechanism was proposed on the basis of the research results. 相似文献
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合成了两种新的聚醚取代的水杨醛亚胺Schiff碱锰(III)配合物MnL12Cl和MnL2Cl,研究了它们与表面活性剂2Brij35形成的金属胶束对BNPP的催化水解反应.探讨了催化反应机理,提出了水解反应的动力学数学模型;计算了催化反应的Michanelis常数和表观活化能,并与不含聚醚链的类似物MnL2Cl比较,考查了配合物配体中聚醚支链及其3端基对催化水解反应的影响.结果表明,催化水解反应遵循金属-氢氧离子机理;以羟基作为聚醚链端基的MnL12Cl的催化活性最高,在相同条件下,其表观一级速率常数约为MnL2Cl的3倍,为MnL2Cl的30倍.23 相似文献
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含聚醚链的Schiff碱锰(III)配合物在胶束溶液中催化BNPP水解反应的研究 总被引:1,自引:0,他引:1
合成了两种新的聚醚取代的水杨醛亚胺Schiff 碱锰(III)配合物和, 研究了它们与表面活性剂Brij35形成的金属胶束对BNPP的催化水解反应. 探讨了催化反应机理, 提出了水解反应的动力学数学模型; 计算了催化反应的Michanelis常数和表观活化能, 并与不含聚醚链的类似物比较, 考查了配合物配体中聚醚支链及其端基对催化水解反应的影响. 结果表明, 催化水解反应遵循金属-氢氧离子机理; 以羟基作为聚醚链端基的的催化活性最高, 在相同条件下, 其表观一级速率常数约为的3倍, 为的30倍. 相似文献
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Four novel pyridine or benzene ring‐containing pendant macrocyclic dioxotetraamines 2,6‐dixo‐l,4,7,10‐tetraazacyclododecane ligands have been synthesized. Their metal complexes have been investigated as catalysts for the hydrolysis of bis(p‐nitrophenyl) phosphate (BNPP) in aqueous comicellar solution. The results indicate mat the hydrophobic interaction between substrate and metal complex, the nature of transition metal ion, and the micellar microenvironment are important factors for the hydrolysis of BNPP. Large rate enhancement (up to over two‐three orders of magnitude) employing 5 has been observed. 相似文献