Abstract
The effects of poly (vinylpyrrolidone) (PVP) on hte alkaline hydrolysis of p-nitrophenyl esters were studied. As ester, p-nitrophenyl acetate, caproate and laurate were used. As PVP, commercial products and the home made samples were Used. The range of malecular welght of PVP examined is between 1.1×104-140×104. The alkaline hydrolysis rate is enhanced by PVP and the enhancement is linear to [OH-] in the concentration range 2×10-0-5×10-4mol/l. The enhaneement appears above a PVP eoncentration, 0.01wt% and increases sharply above 0.1wt%. The enhanCement depends on Mv of PVP to show a maximum between 1×104-5×104 of Mv, When the hydrocarbon group in esters becomes longer, i. e., the hydrophobicity of the ester increases, the enhancement by PVP becomes larger. The reason for the enhancemnt of PVP may be the increased local concentration of both the substrate ester and OH- in the aqueous reaction system. The reactions are also accelerated by poly (ethylene glycol), but decelerated by poly (vinyl alcohol).
