Effect of Reaction Media on Equilibrium and Rate Parameters

Effect of Reaction Media on Equilibrium and Rate Parameters 

Polycondensations must be carried out in bulk or with a concentration of solvent as low as possible (viscosity being the limiting factor) in order to minimize the formation of rings. If the end groups have polarities and/or hydrogen acceptor or do- 

Known examples are the apparent increase in reactivity with conversion in esterifications and the strong effect of water concentration on apparent equilibrium and rate constants in amidation systems (see Sections 3.3.1 and 3.3.3 respectively). 

Should some thermodynamic model of the chemical system be available, knowledge of activity coefficients y of chemical groups A, B, Z and by-product W would allow the apparent equilibrium ratio K to be related to the thermodynamic K (a true constant, a function only of temperature) through Eq. (10). 

This kind of computation can be done using the UNIFAC contribution group method [11], but its empirical character and lack of available parameters at high temperatures limit drastically its usefulness. 

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