Modification of the reactivity of a small molecule by reversible association with a synthetic polymer. Inhibition of the hydrolysis of cationic esters by polyanions

Abstract

The base‐catalyzed hydrolysis rate of the cationic esters obtained by quaternization of N,N,N′,N′‐tetramethylethylenediamine with phenylbromoacetate was studied in buffers and in solutions of partially neutralized polymeric acids. The polyanions were found to be powerful inhibitors of the reaction. This effect was interpreted as due to the association of the ester with the polyanion, from which the catalytically active hydroxyl groups are repelled. It is shown that kinetic data may be interpreted by a procedure similar to the Lineweaver‐Burk plot to yield the reactivity of the bound ester and the dissociation constant of the polymer–ester complex.

Microgels as matrices for molecular receptor and reactive sites: synthesis and reactivity of cavities possessing amino-functions

“…21 Overberger 22 showed that a polymer with carboxylate subunits exhibits marked selectivity towards a positively charged substrate as does partially protonated poly(vinylimidazo1e) towards negatively charged substrates in Reversible association of positively charged substrates was demonstrated for poly(acry1ic acids) by Morawetz and Shafer. 24 The minimum catalytic effect of poly(vinylimidazo1e) on the hydrolysis of 4-nitrophenyl acetate was shown to occur at a solvent composition where viscosity was at its maximum due to ' opening up ' of the polymer to give long chains. The highest rate of reaction was at low ethanol content where the polymer chains had ' balled up ' to form hydrophobic domains.…”