Molecular thermodynamics for chemical reaction design

Abstract

Various techniques of molecular thermodynamics and solution theory have been applied, through the transition state theory, to problems in chemical kinetics. These include experimental techniques for ascertaining the structure and properties of the transition states for various classes of reactions, plus analytical methods for using this information to predict the effect of solvents or reactant structure on chemical reaction rates. Such methods provide the chemical engineer with an additional parameter to use in the optimal design of reaction systems–that is, the chemistry of the reaction itself.

Reactions at supercritical conditions: Applications and fundamentals

“…One could also develop an alternate expression for the transition-state theory rate constant that employs fugacity coefficients rather than activity coefficients (Eckert et al, 1974). This alternate form of the rate constant is convenient to use when an accurate analytical equation of state is available for the fluid phase.…”

“…From Eq. 4, it is evident that we can relate the rate constant for this bimolecular reaction in a given solvent to the rate constant, k,, in an ideal fluid phase as k := k,( -) YA Y B 'YMt (11) Eckert (1972) and Eckert et al (1974) described methods for using molecular thermodynamics to evaluate these activity coefficients and thereby quantify solvent effects on chemical kinetics for some cases. One can use regular solution theory, for example, which gives the activity coefficient as where S, and are the solubility parameter and molar volume of component i, and 8 is the solubility parameter of the solvent.…”

“…The data required for the reactants in Eq. 13 are often available, and Eckert et al (1974) describe how one can use measured molar volumes and these pure-component properties to estimate the required properties for the transition state. Alternatively, one could simplify the problem by assuming that the molar volume of the activated complex is equal to the sum of the molar volumes of the reactants:…”

Thermodynamic Aspects of Supercritical Fluids Processing: Applications of Polymers and Wastes Treatment

“…The different types of reactions will be no more developed and the kinetic and diffusion control studies are not presented in regard of the rich literature related to these fields [9,68,69,78,79].…”

“…mol -1 . s -1 , k 0 is the rate constant in the ideal reference system (g A = g B = g M * = 1) and the g's are the activity coefficients in the mixture [67] and [68].…”