Suppression of the rate of hydrolysis of t-amylchloride at the consolute composition of isobutyric acid+water

We have measured the rate of hydrolysis of t-amylchloride in the solvent, isobutyric acid+water, prepared at its consolute composition. The consolute temperature of the mixture depends upon the initial amount of t-amylchloride, being 32.3°C when 100 μl are added to 25 ml of the solvent and 36.46°C when 150 μl are added. In both cases, however, we found that the specific rate of reaction is suppressed over a temperature range of about 0.2°C on either side of the local consolute temperature, Tc. These observations serve to demonstrate the concept of `critical slowing downʹ in chemical kinetics. The decrease in specific rate with temperature, T, could be fitted by |T−Tc|−x with x=0.63±0.28. Within the experimental error, this value of the exponent is consistent with the value (x=0.80) predicted theoretically on the basis of the principle of universality.