Theoretical Analysis of Chemical Reaction in Frozen State (Part 2) : Introduction of a More Accurate Freezing Point Depression

Acceleration of chemical reactions in the frozen state has become of interest in recent years because of its unique characteristics. To give a theoretical interpretation for the acceleration mechanism of such reactions, a new equation is derived. The equation is essentially the product of Arrhenius formula of temperature effect and the term of liquid concentration varied with freezing ratio. In the previous paper (Murata et al., 1992)) for calculating the freezing ratio the Heiss formula was used. In this case, a more accurate freezing point depression is introduced and the error of the optimum temperature of reaction between calculated result and experimental result is reduced from 1.8℃ to 0.2℃. For calculation, the kinetic data obtained for the acid-catalyzed deformilation of Nacetyl-N’-formly-L-kynureninneamide (Yamasaki et al., 1976b) are used. The results clearly indicate that the calculated first -order rate constants at various temperatures are in good agreement with the experimental data. The acceleration of the deformylation of N’-formylkynurenine in the frozen acidic solutions can be interpreted as being due to the concentration of the reactants in the liquid region in ice crystals