Thermochemistry of Ionic Liquid-Catalyzed Reactions: Theoretical and Experimental Study of the Beckmann Rearrangement-Kinetic or Thermodynamic Control?

A thermodynamic analysis of the experimental conditions of the Beckmann rearrangement reaction of oximes into amides has been undertaken to examine whether the reaction is under thermodynamic or kinetic control. To answer this question, the thermodynamic properties of the typical Beckmann rearrangement reactions in the ideal gaseous state-cyclohexanone oxime to caprolactam and 2-butanone oxime to N-methylpropanarnide-were studied by using the quantum mechanical method. Gibbs energy and equilibrium constants of the Beckmann rearrangement have been assessed in the gaseous and the liquid phases. Results of the thermodynamic analysis have shown that Beckmann rearrange ments are kinetically controlled. Thus, a search for possible active ionic liquid based catalysts for the mild reaction conditions has been performed.

Kinetic and thermodynamic investigations on arsenic adsorption onto dolomitic sorbents

Arsenic and its compounds are toxic pollutants for the environment and all living organisms. At present, there is considerable interest in studying new sorbent materials for the removal of arsenic from aqueous solutions. This work discusses the feasibility of arsenic uptake onto dolomite which is considered to be a potential inexpensive adsorbent. Thermodynamic and kinetic experiments were undertaken to assess the capacity and rate of As uptake onto dolomite. Experimental data were mathematically described using adsorption kinetic models, namely pseudo-first-order and pseudo-second-order models. The arsenic removal was found to be dependent on the dosage of dolomite, adsorbent particle size and the presence of various anions. Thermodynamic results indicate that the adsorption follows an exothermic chemisorption process. The experimental data indicate successful removal of As(V) ion from aqueous solution indicating that dolomite be used as an inexpensive treatment process. (C) 2010 Elsevier B.V. All rights reserved.