有机污染物水解速度常数与腐殖质浓度定量关系的建立及验证

水解是有机污染物转化降解的重要途径.天然水体中的腐殖质影响有机化合物的水解速度常数,使之与蒸馏水缓冲系统中的测定值有较大差别.本文推导并验证了腐殖质浓度与水解速度常数的定量关系,测定了腐殖质与有机化合物的缔合系数.     

有机相脂肪酶催化水解椰子油的研究

有机相脂肪酶催化水解椰子油的研究缪德埙，尉迟力，李树本（中国科学院兰州化学物理研究所羰基合成与选择氧化国家重点实验室，兰州７３００００）曹淑桂（吉林大学酶工程国家重点实验室，长春１３００２３）关键词椰子油，酶，催化水解。１．前言脂肪酶从６０年代已开始...     

活性炭催化碳酸二甲酯水解行为的研究

以无氯Cu/AC催化剂中活性炭载体为研究对象,对活性炭上DMC水解反应条件进行了考察,并通过Boehm滴定法和XPS对活性炭上DMC水解活性位点进行了分析。结果表明,温度的升高和水含量的增加对DMC水解有较大的促进作用,较高的压力和CO₂气氛对DMC水解有一定的抑制作用,甲醇量和CO、O₂、N₂气氛对DMC水解影响较小。不同条件处理的活性炭表面基团种类、数量均有较大变化,HNO₃处理使活性炭碱性基团含量下降,羧基等酸性含氧官能团含量明显增加,总酸量最高可达1.88 mmol·g^-1;先HNO₃后NaOH处理的活性炭上酸性基团含量大量减少,表面碱性基团含量则有较大提高,总碱量最高可达1.69 mmol·g^-1。特别地,活性炭表面碱性基团是催化DMC水解的活性位点,在活性炭碱性基团含量由0.16增加到1.69 mmol·g^-1的过程中,DMC水解程度由2.5%增加到了31.7%,而酸处理可以有效降低活性炭表面碱性基团含量,抑制其催化DMC的水解性能。     

活性炭催化碳酸二甲酯水解行为的研究

以无氯Cu/AC催化剂中活性炭载体为研究对象,对活性炭上DMC水解反应条件进行了考察,并通过Boehm滴定法和XPS对活性炭上DMC水解活性位点进行了分析。结果表明,温度的升高和水含量的增加对DMC水解有较大的促进作用,较高的压力和CO_2气氛对DMC水解有一定的抑制作用,甲醇量和CO、O_2、N_2气氛对DMC水解影响较小。不同条件处理的活性炭表面基团种类、数量均有较大变化,HNO_3处理使活性炭碱性基团含量下降,羧基等酸性含氧官能团含量明显增加,总酸量最高可达1.88 mmol·g~(-1);先HNO_3后NaOH处理的活性炭上酸性基团含量大量减少,表面碱性基团含量则有较大提高,总碱量最高可达1.69 mmol·g-1。特别地,活性炭表面碱性基团是催化DMC水解的活性位点,在活性炭碱性基团含量由0.16增加到1.69mmol·g~(-1)的过程中,DMC水解程度由2.5%增加到了31.7%,而酸处理可以有效降低活性炭表面碱性基团含量,抑制其催化DMC的水解性能。     

吡啶乙炔苯甲腈类化合物的制备

对苯乙炔和吡啶乙炔类化合物的Heck反应进行了较全面的论述和仔细的研究,发现溶剂对催化体系有重要的影响。并成功的改进了一个Pd催化偶合反应。将该反应用于吡啶乙炔苯甲腈类化合物的合成。四个新的吡啶乙炔苯甲腈化合物被首次合成出来,从而为该类化合物的合成提供了一个有效而又方便的方法。     

应用HPLC对氨基酸和肽水解稳定性的实验研究

水解蛋白质的实验条件通常很强烈,正如预期的那样,在此条件下有些氨基酸依据不同的介质以不可预料的方式分解[1].如果水解在足够温和的条件下进行,蛋白质水解液中除了含有氨基酸外,还有一系列的肽.反相高效液相色谱的柱前衍生法对氨基酸和肽的分离分析具有分析时间短和灵敏度高的优点.在前文中[2]已对9-芴甲基氯甲酸酯(FMOC-Cl)作为氨基酸和肽的衍生化试剂的衍生介质和衍生化条件进行了研究.绝对分析法用于对水解收率的计算,在一定的实验条件下,它能直接给出收率[3～5].……     

扁桃甙水解和极谱行为的研究

通过测定产物间接测定扁桃甙,如用酶修饰电极测定产物氢氰酸和葡萄糖,其检测限均在10~(-5) mol/L。本文首次采用卷积伏安法研究了扁桃甙的水解以及产物苯甲醛的极谱行为,提高了扁桃甙的检测限。 1 仪器与试剂 XJP-821型新极谱仪(长春应用化学研究所、江苏电分析仪器厂),三电极体系,LZ3-100     

NAMI-A乙基取代衍生物水解机理的DFT研究

采用密度泛函理论(DFT)方法,并结合导体极化连续模型(CPCM)研究了[(N-EtIm)H][trans-RuⅢCl4(DMSO)(N-EtIm)](N-EtIm=N-乙基咪唑)分别在中性及酸性条件下的水解反应过程.同时,为提高溶剂化能的精确度,在中性条件下水解反应的计算中采用3个水分子的溶剂化模型.计算得到水解反应过程中相应的结构特征和详细的热力学能量及速率常数.首先,在中性条件下,对于第一步水解,液相中配合物的活化能垒为109.9kJ/mol,速率常数为3.3×10-7 s-1,与实验中测得的第一步水解反应的速率常数(4.4×10-7 s-1)一致.对于第二步水解,反应的活化能垒为117.9kJ/mol,这符合实验中观察到的第二步水解比第一步水解反应慢的现象.其次,计算结果表明,酸性条件下,DMSO基团易于水解,Cl-水解困难,这也与实验结果相吻合.     

聚酯-酰胺的水解降解行为

研究了各种条件下聚酯-酰胺的水解降解行为及其与结构之间的关系。结果表明：酯键含量越高,质量损失就越快。聚合物的降解受酸、碱催化。根据SEM观察提出了可能发生的降解机理：表面腐蚀、非晶区腐蚀、晶区破坏到全部降解。     

Brightly full-color emissions of oligo(p-phenylenevinylene)s: substituent effects on photophysical properties

A simple and effective strategy for synthesis of bis-dipolar trimeric OPVs (a-g) with same push-pull electron groups at the two ends is presented. Their photophysical and electrochemical properties were investigated by UV-vis, fluorescence spectroscopies, and voltammetry techniques. A successful tuning in the emission color was achieved and the LUMO energy level was found to correlate with the Hammett constant of the respective substituents, providing a powerful strategy for prediction of the photoelectrical properties of the new chromophores.     

Synthesis, characterization, and substituent effects of mononuclear ruthenium complexes [RuCl(CO)(PMe3)3(CHCH-C6H4-R-p)] (R = H, CH3, OCH3, NO2, NH2, NMe2)

A series of mononuclear ruthenium complexes [RuCl(CO)(PMe₃)₃(CHCH-C₆H₄-R-p)] (R = H (2a), CH₃ (2b), OCH₃ (2c), NO₂ (2d), NH₂ (2e), NMe₂ (2f)) has been prepared. The respective products have been characterized by elemental analyses, NMR spectrometry, and UV-Vis spectrophotometry. The structures of complexes 2c and 2d have been established by X-ray crystallography. Electrochemical studies have revealed that electron-releasing substituents facilitate monometallic ruthenium complex oxidation, and the substituent parameter values (σ) show a strong linear correlation with the anodic half-wave or oxidation peak potentials of the complexes.     

An analysis on the transmission of electron density through sulphur atoms in the quaternization reactions of benzothiazoles

The kinetics of quaternization of a number of 2-substituted benzothiazoles with alkyl iodides and phenacyl bromide have been studied in nitrobenzene. The order of reactivity of different substituted benzothiazoles has been found to be -H > NO₂ > Cl. The relative reactivity of 2-amino and 2-methyl derivatives has been ascribed to a solvation phenomenon. The analysis of rho values from the Hammett equation suggests two possible routes for the transmission of electron density.     

Hammett-type relationship for the cleavage of radical anions of aromatic chlorides and bromides

A Hammett-type correlation pertaining to the cleavage of radical anions of aromatic halides has been formulated. The expression has been verified using the reaction series of aromatic chlorides and bromides. The correlation reveals the sensitive nature of the carbon-chlorine bond to the polar effects of the substituents in comparison to the carbon-bromine bond. The cleavage rate constants of radical anions of some aromatic chlorides and bromides have been deduced using the correlation. The standard potentials for formation of radical anions of aromatic chlorides and bromides have been estimated based on the correlation.     

Synthesis and Investigation of Ring-chain Isomerism of the Derivatives of N-Amino-5-hydroxy-1,2,3-triazole-4-carboxylic Acid

A series of sodium salts of 4-substituted 1-amino-5-hydroxy-1,2,3-triazoles was obtained by the diazo transfer reaction to arylmethylene-protected -ethoxycarbonyl- and -(methylcarbamoyl)-acetohydrazides. In DMSO solution the corresponding neutral hydroxytriazoles exist in equilibrium with the isomeric diazo compounds with an open chain. Electron-donating substituents stabilize the cyclic form. A good correlation was obtained between the equilibrium constants and the Hammett -constants. During the diazotization of benzaldehyde -amino--cyanoacetylhydrazone the initially formed diazo compound undergoes spontaneous cyclization in solution to hydroxytriazole. Removal of the arylmethylene protection leads to N-unsubstituted sodium salts of 1-amino-5-hydroxytriazoles, but acidification of the latter leads to diazoacetohydrazides with an open chain.     

A stress tensor and QTAIM perspective on the substituent effects of biphenyl subjected to torsion

The Quantum Theory of Atoms in Molecules (QTAIM) defines quantities in 3D space that can be easily obtained from routine quantum chemical calculations. The present investigation shows that local properties can be related quantitatively to measures traditionally connected to experimental data, such as Hammett constants. We consider the specific case of substituted biphenyl to quantify the effects of a torsion φ, 0.0° ≤ φ ≤ 180.0°, of the C—C bond linking the two phenyl rings for C₁₂H₉‐x, where x = N(CH₃)₂, NH₂, CH₃, CHO, CN, NO_2, on the entire molecule. QTAIM interpreted Hammett constants, aΔH( r_b ) are introduced and constructed using the difference between the H( r_b ) value of C₁₂H₉‐x and the C₁₂H₉‐H, biphenyl which is the reference molecule, with a constant of proportionality a. This investigation unexpectedly yields very good or good agreement for the x groups with the Hammett para‐, meta‐, and ortho‐substituent constants and is checked against para‐substituted benzene. We then proceed to present the interpreted substituent constants of seven new biphenyl substituent groups, where tabulated Hammett substituent constant values are not available; y = SiH₃, ZnCl, COOCH₃, SO₂NH₂, SO₂OH, COCl, CB₃. Consistency is found for the QTAIM interpreted biphenyl substituent constants of the seven new groups y independently using the stress tensor polarizability P_σ. In addition, a selection of future applications is discussed that highlight the usefulness of this approach. © 2016 Wiley Periodicals, Inc.     

Zur Kinetik der Isobutenhydratation in Schwefelsäure-Wasser—t-Butanollösungen

The reaction rate constants of the hydratization of isobutene in aqueous sulfuric acid—tert-butanol solutions can be correlated with theHammett acidity function. The activity energy depends on the concentration oftert-butanol. On the basis of the given correlation it is possible to extrapolate reaction rate constants beyond the kinetic regime of the isobutene hydratization.

     

Substituent effects of α,β-unsaturated aldehyde compounds in inverse electron demand Hetero-Diels–Alder reactions: A theoretical study

The present work describes the new theoretical study for behaviour estimation of some α,β-unsaturated aldehyde derivatives in inverse electron demand Hetero-Diels–Alder reactions. The theoretical scale has shown rationalization between electrophilic activation/deactivation effects and electron withdrawing (EW) and electron releasing (ER) substituents in these molecules. The electrophilicity values that evaluated with HF/6-31G* method shows a good linear relationship with the σ_p Hammett substituent constants. These results are in excellent agreement with respect to experimental results.     

Study on Thermodynamics and Kinetics of Association Interactions between Malachite Green and OP-10 in Aqueous Solutions

The absorption spectrum of malachite green (MG) in a series of aqueous solutions with surfactant octylphenol polyoxyethylene ether (10) (OP-10) has been determined by the UV–Vis spectrophotometer. The association interaction between the MG and nonionic surfactant OP-10 in aqueous solutions resulted in obvious fading of MG. We established the thermodynamics model of association between MG and OP-10, and determined the association equilibrium constant in aqueous solutions. By measuring the absorbance of a series of aqueous solutions which have different molar concentrations of OP-10 but same concentration of MG at different time points, the order and rate constants of association reactions were determined and the reaction kinetics equation was set up.     

Kinetics of Hydrolysis of Inosine in Aqueous Solutions

The kinetics of hydrolysis of inosine was studied in aqueous solution at 353 K over a pH range of 0.45 - 12.13. The decomposition was followed by HPLC. The pH - profile was accounted for by assuming spontaneous water-catalyzed decomposition of the inosine molecules at various degrees of dissociation.