Fast Reactions in Solutions under Pressure II: Pressure Dependence of Very Fast Proton Transfer Reactions. Reaction of Alizarin Yellow GG with OH− up to 1500 bar at T = 283.2 K

Equilibrium and rate constants of the hydrolytic reaction of the azo dye alizarin yellow GG with OH− are reported for pressures up to 1500 bar at T = 283.2 K. From the pressure dependence of the equilibrium constant the volume of reaction was found to be ΔV = +(13.3 ± 1.3) cm3 mol−1. The pressure dependence of the overall rate constants yields a volume of activation of ΔV≠ = +(10.3 + 1.5) cm3 mol−1 and ΔV≠ = −(5.1 + 1.5) cm3 mol−1 for the forward and backward reaction, respectively. With the help of theoretical calculation of diffusion controlled reactions, volumes of reaction for intermediate steps are obtained.