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The catalytic hydrolysis of bis(4-nitrophenyl)phosphate (BNPP) by lanthanum(III) ion in the presence of amino-alcoholic ligands: diethanolamine (DEA) and triethanolamine (TEA), was investigated kinetically at 30 °C. The results indicated that the dinuclear dihydroxo complexes formed by lanthanum(III) ion with aminoalcoholic ligands might be the catalytically active species which catalyze the hydrolysis of BNPP to different extents and the catalytic mechanism was believed to involve the synergism of double Lewis acid activation of the substrate and an intramolecular nucleophilic attack of a bridging oxo ligand.

The hydrolysis of bis(4‐nitrophenyl) phosphate (BNPP) catalyzed by metallomicelles formed from three asymmetry oxamido‐bridged Cu(II)Ni(II) heterodinuclear complexes containing different diamine groups and Brij35 micelle has been investigated kinetically in the pH range of 6.0–10.0 at 25°C. The results indicate that these complexes show relative high reactivity in Brij35 micellar solutions. Complex III exhibited a more effective catalytic function than complex I and complex II for the hydrolysis of BNPP, which was attributed to the different structure of the diamine group in the complex. The apparent rate constants (k obsd ) of BNPP hydrolysis increased with the increasing pH values of reaction media and then reached saturation near pH 9.0. The kinetic and thermodynamic parameters (K and k) were obtained, and the studies show that the hydrolysis of BNPP involves a bifunctional mechanism and is an intramolecular nucleophilic reaction. In the reaction systems, the kinetically active species has been determi...

The hydrolysis of (p-nitrophenyl)phosphate (NPP) catalyzed by the Cu(II), Zn(II), Ni(II) and Co(II) complexes of lipophilic pyridine-containing alkanol ligands were investigated in the presence of an inert surfactant (CTAB). The experimental results indicate that 2:1 ligand:metal ion complexes in CTAB micellar solution are the active species for the catalytic hydrolysis of NPP. The ternary complex kinetic model for metallomicellar catalysis was employed to treat with the results, so as to obtain the relative kinetic and thermodynamic parameters. The results predicted the reasonability of such kinetic models.

The reactions of hydroquinone with hydrogen peroxide catalyzed by transition metal ions Cu2+, Fe2+, Fe3+, Co2+ and Mn2+ were investigated in aqueous solution at 25 degrees C. Two copper (II) complexes (bis(dimethylglyoxime) copper(II) and 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-dienatocopper(II)iodide) were prepared. Their catalytic activities on this oxidation were kinetically investigated in aqueous solution and in cetyltrimethylammonium bromide (CTAB) micellar solution at 25 degrees C. The kinetic equations for micellar catalysis and metallomicellar catalysis were established, respectively. CTAB micelle enhances the reaction rate due to its concentrated and electrostatic effects on substrates and/or intermediate. Metallomicelle exhibits remarkable catalytic activity on this oxidation reaction, which is attributed to the active center and the microenvironment effects. Metallomicelle enhances the rate of reaction by activating hydroquinone anion. The presence of co-ligand of imidazole (or pyridine) remarkably increases the catalytic activity of metal complex in micelle system in contrast to it lowers the activity of the complex in aqueous solution. Metallomicelles could be treated as the mimic models of peroxidase.

The Schiff base complexes containing a transition metal ion, CoII and CuII, were used as mimetic peroxidase in the catalytic oxidation of phenol by H2O2. The characteristic spectra of the Schiff base complexes in H2O2-buffered solution were recorded and analyzed, respectively. The mechanism and the kinetic mathematic model of the phenol catalytic oxidation were studied. The results showed that the Schiff base complexes containing the transition metal ion, CoII and CuII, as peroxidase mimics exhibited good catalytic activity and the character of the peroxidase in the catalytic oxidation of phenol by H2O2 under different conditions.

The comparative kinetic investigation of the hydrolysis of p-nitrophenyl picolinate (PNPP) and p-nitrophenyl acetate (PNPA) catalyzed by the tetracoordinate macrocyclic Schiff base complex of zinc(II) (1) at 30 °C is reported. The results indicate that the (1) catalyzed hydrolyses of PNPP and PNPA are acid-base catalytic processes and that the active species is the metal bound hydroxide ion, namely, ZnL—OH−. (1) promoted hydrolysis of PNPP proceeds much faster than that of PNPA. At pH 7.51, the apparent second-order rate constants kc for hydrolysis of PNPP and PNPA are 0.254 and 7.28 × 10−3 mol−1 dm3 s−1, respectively. The difference in hydrolytic rates may be attributed to the difference of hydrolytic mechanisms by which the PNPP and PNPA operate. The reasons are discussed in detail.

A novel difunctional magnetic nanocatalyst (DMNC) was prepared and used to catalyse the hydrolytic breakage of β-1,4-glycosidic bonds. The functional nanoparticle displayed excellent catalytic activity for hydrolysis of cellobiose to glucose under moderate conditions. The conversion of cellobiose and yield of glucose could reach 95.3 and 91.1 %, respectively, for a reaction time of 6 h at pH 4.0 and 130°C. DMNC was also an efficient catalyst for the hydrolysis of cellulose: 53.9 % microcrystalline cellulose was hydrolyzed, and 45.7 % reducing sugar was obtained at pH 4.0 and 130°C after 10 h. The magnetic catalyst could be recycled and reused five times without significant loss of catalytic activity.

This paper presents a novel data processing method for thermokinetics of faster first-order reaction on the basis of the double-parameter theoretical model of a conduction calorimeter, in which the rate constant of a first-order reaction can be calculated from only four peak height data from the same thermoanalytical curve without using any peak-area. The saponifications of ethyl acetate and methyl acetate in aqueous solution and ethyl benzoate in aqueous alcohol have been studied to test the validity of this method. The rate constants calculated with this method are in fair agreement with those in literature; hence the validity of this method is demonstrated.

A novel thermokinetic research method for determination of the rate constant of a reaction taking place in a batch conduction calorimeter under isothermal conditions is proposed: the double-thermoanalytical curve method. The method needs only the characteristic time parameter tm, the peak height Δm at time tm and the peak area a*m after time tm for two thermoanalytical curves measured with different initial concentrations of the reactants: it conveniently calculates the rate constants. The thermokinetics of four reaction systems were studied with this method, and its validity was verified by the experimental results.

The oxidative coupling reaction of 2,6-dimethylphenol with H 2 O 2 catalyzed by a copper(II) Schiff complex in aqueous and Triton X-100 micellar solution under mild conditions was investigated. The kinetics of formation of 3,3′,5,5′-tetramethyl-4,4′-diphenoquinone (DPQ) was studied. Rate constant k 2 were obtained. The optimum pH for DPQ generation reaction is 7.25. The main product was DPQ in aqueous buffer solution, but PPE and the oxidized products of PPE remained in Triton X-100 micellar solution.

The oxidative coupling reaction of 2,6-dimethylphenol (DMP) with H2O2 catalyzed by four copper(II) complexes was investigated in Tris-HNO3 buffer solution at 25°C. The kinetics of formation of diphenoquinone (DPQ, 4-(3,5-dimethyl-4-oxo-2,5-cyclohexadienylidene)-2,6-dimethyl-2,5-cyclohexadienone) from DMP was studied in detail. The kinetic parameters k2 and Km were obtained in the pH range of 6.0–9.0. The copper(II) complexes exhibited the optimal catalytic activity at around pH 7.0. The pH effect was reasonably explicated by the catalytic kinetic model suggested in this work. The catalytic mechanism was discussed. The deprotonized associated radical LCuI(OH−)-•OOH was suggested as the possible predominant species to oxidize DMP. The CC and CO coupling products were analyzed and the ratio of poly (2,6-dimethyl-1,4-phenylene ether) (PPE) to DPQ was also evaluated. Both in weak acidic (pH 8) were suitable to the CO coupling reaction in our catalytic systems. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Functional chitosan, chemically modified by salicylaldehyde (CS-SA), β-cyclodextrin (CS-CD), and a cross-linked β-cyclodextrin polymer (EPI-CD) were prepared as adsorbents to remove phenol, p-nitrophenol and p-chlorophenol from aqueous solution. Langmuir and Freundlich models were applied to describe the adsorption isotherm of phenols, and adsorption parameters were evaluated. Functional chitosan displayed outstanding adsorption ability for phenols. To our surprise, CS-CD exhibited specific adsorption ability for p-chlorophenol. The possible adsorption interaction was discussed. Effects of pH and KCl on the adsorption suggested that the adsorption of phenols was predominated by hydrogen bonding, hydrophobic interaction and π–π interaction not electrostatic interaction. Effect of temperature indicated that the low temperature was favorable for the adsorption of phenols. Separation of phenols and adsorbent regeneration were carried out by simple washing with ethanol and filtrating.

The catalytic hydrolysis of bis(p-nitrophenyl) phosphate (BNPP) and p-nitrophenyl phosphate (NPP) by metallomicelles composed of Cu(II) or Zn(II) complexes of bispyridine-containing alkanol ligands in CTAB micellar solution was investigated at 30 degrees C. The experimental results indicate that the complexes with a 1:1 ratio of ligands to metal ions for ligands 1 (1,7-bis(6-hydroxymethyl-2-pyridyl)-2,6-dioxaheptane) and 3 (1,4-bis[(6-hydroxymethyl-2-pyridyl)-2-oxapropyl]benzene) and a 1:2 ratio of ligands to metal ions for ligand 2 (1,14-bis(6-hydroxymethyl-2-pyridyl)-2,13-dioxatetradecane) in CATB micellar solution are the active species for the catalytic hydrolysis of BNPP and NPP, respectively. The ternary complex kinetic model for metallomicellar catalysis was employed to obtain the relative kinetic and thermodynamic parameters, which demonstrated the catalytic mechanism for the hydrolysis of BNPP and NPP by metallomicelles.

The reaction pathways and kinetics of the oxidation reactions of 1-phenylethyl alcohol (PEA), 1-(3,4-dimethoxyphenyl)ethanol (MVA), 1-(4-hydroxy-3-methoxyphenyl)ethanol (HMOPE), 1-(3-aminophenyl)ethanol (APE), 1-(4-methylphenyl)ethanol (MPE) and cyclohexanol with performic acid (PFA) were investigated in formic acid solvent. An unexpected new reaction pathway, from which the secondary alcohols can be directly oxidized to corresponding esters, was found. The reaction products (esters and ketones) of oxidation of PEA, MVA, HMOPE, APE, MPE and cyclohexanol were detected at different reaction times. The reaction rate constants, k1, k2, k3 and power orders α, β, γ of PFA concentration for three oxidation reactions pathways: alcohol to ester, alcohol to ketone and ketone to ester were obtained, respectively. These findings might provide a new insight into the technology of lignin degradation.