The Influence of Hydrophobic Solvation on the Alkaline Hydrolysis of Ethyl Esters of Polar Substituted 2-Methylpropionic Acids in Water

Article abstract of DOI:10.1007/BF00652543

The rate constants of the alkaline hydrolysis of 2-methylpropionic acid ethyl ester, α-hydroxy, α-bromo, α-cyano, and α-nitro-2-methylpropionic acid ethyl ester have been measured in water between 5 deg C and 45 deg C with the help of an appropiate conductance bridge developed in our laboratory.The influence of the polar substituents on the rate constant, a powerful probe for discussing two-particle interactions in solutions, is characterized by an intramolecular structure parameter of the activated complex and a dielectric parameter of its surroundings.The dependence of the reaction rate on the structure parameter is compared to that of substituted acetic acid derivatives.The smaller dielectric parameter of 2-methylpropionic acid esters reveals the increasing hydrophobic solvation in comparison to acetic acid derivatives.