1,721,160 research outputs found
Effect of Methyl Substituents on the Reactivity of p-Bromonitrobenzene towards Sodium Toluene-p-thiolate in Dimethylformamide
No full textKinetics of the reaction of toluene with benzyl alcohol over a Nafion-silica composite
No full textThe title reaction, a set of concurrent-consecutive steps, was studied in a slurry batch reactor at 50, 65, and 75 degrees C, using cyclohexane as solvent and Nafion SAC-13 as solid acid catalyst. The final products were found to be dibenzylether, the isomers of benzyltoluene and dibenzyltoluenes and small amounts of unidentified byproducts. The kinetic results were interpreted by a Langmuir-Hinshelwood model, evaluating the main kinetics and adsorption coefficient involved in the reactions and their temperature dependence. (c) 2004 Elsevier B.V. All rights reserved
Influence of Feed Concentration on the Kinetics of Biodegradation of Phenol in a Continuous Stirred Reactor
No full textThe rate of phenol degradation by activated sludge was studied in a completely mixed continuous-flow reactor with sludge recycle, operated at steady-state conditions at 20°C. Monod kinetics was followed when the influent concentration (Cs°) was kept constant. When using different Cs° levels, the phenol removal rate was found to have an inverse dependence on Cs°. It is suggested that this kinetic anomaly is due to inhibition of the biooxidation by some secondary reaction product(s). A kinetic model based on this concept is able to interpret experimental facts
Kinetics of aromatic nucleophilic substitution by toluene-p-thiolate in dimethylformamide. Effect of solvent on Hammett-type correlations
No full textThe kinetics of the reaction of some 4-substituted 2-nitrochlorobenzenes with toluene-p-thiolate in dimethylformamide have been measured at temperatures from -39.7 to 71.9°C. Correlation of rates by Hammett-type equations gives, using the best set of σ values, ρ = +6.65 at 10°C. The dependence of the ρ value on the solvent is discussed. A comparison of these reactions with those of Ar2C=CHCl and of ArC≡CCl with the same nucleophile-solvent system shows that the substituent effects are markedly attenuated by the interposition of C=C or C≡C bonds
Comment on Development of a General Kinetic Model for Biodegradation and Its Application to Chlorophenols and Related Compounds
No full textInhbiting Action of Chloro- and Nitro-phenols on Biodegradation of Phenol: A Structure-Toxicity Relationship
No full textAll chlorophenols and six mono- and di-nitrophenols were tested, by discontinuous kinetic measurements, as inhibitors of the phenol degradation by activated sludge. The measured values of pI50 were correlated with structural properties (logP, ε{lunate}σ) of the substituted phenols, developing a QSAR
Kinetics and Byproducts of the Liquid-Phase Oxidation of Phenol to p-Benzoquinone Catalyzed by CuCl2
No full textOxidation of phenol was effected by O//2 at 35 kg/cm**2 in dimethylformamide (DMF), dimethyl sulfoxide (Me//2SO), and other solvents, containing variable amounts of CuCl//2 (0. 20-0. 50 mol/L), at temperatures in the range from 50 to 1110 degree C. Besides p-benzoquinone, considerable amounts of o- and p-chlorophenol were identified in the products, their yield strongly depending on the solvent. On the basis of overall conversion of phenol and of selectivity for p-benzoquinone, solvents of dipolar aprotic character, particularly DMF, were found convenient; ethylene glycol gave the poorest results. Kinetic coefficients were evaluated, within the pseudo-first-order approximation, for reactions in DMF and in Me//2SO. The steel surface of the autoclave was found to interfere with the reaction. After PTFE-lining, both rate and selectivity changes are observed
LIPOPHILIC AND ELECTROPHILIC FACTORS IN THE INHIBITING ACTION OF SUBSTITUTED PHENOLS ON THE BIODEGRADATION OF PHENOL
No full textMonosubstituted phenols (meta or para substituents: MeO, C1, CN, NO2) were used as inhibitors of the phenol degradation by an activated sludge. By kinetic measurements, the inhibiting action was expressed as pI50, and the latter quantity was correlated with structural properties (logP, σ) of the inhibitors. The QSAR referring to the present system is compared with previous correlations based on different sludges and different sets of inhibitors, showing that the largely predominant factor of phenolic inhibition can be the phenol's lipophilicity
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