Effect of solvent phase transitions on the rate of aminolysis of the methyl ester of a protected dipeptide at high pressures

The rate of aminolysis involving the methyl ester of o-nitrophenylsulfenylglycylphenylalanine (I) and benzylamine (II) rises discontinuously upon realization of a phase transition of the solvent in the solid state at high pressures by about three orders of magnitude. Such behavior may be attributed only to a maximum possible change in concentration of the reagents but is also related to an increase in their reactivity as an apparent result of a change in interaction with the environment. This is also indicated by the more significant accelerating effect of pressure (P) on the reaction when the solvent is in the solid state. Thus, in DMF the rate constant (k) of the reaction is first-order ((II)