Catalytic Activity of Poly(α-sulfoundecenoic acid)

Abstract

Poly(α-sulfoundecenoic acid), poly(SUA-H), was prepared from poly(undecenoic acid), poly(UA-H). The critical micelle concentration, CMC, and pre-CMC of poly(SUA-H), estimated with measurement of electric conductivity of the aqueous solution, were slightly higher than those of poly(sodium undecenoate), poly(UA-Na), and benzene was solubilized into aqueous solution of poly(SUA-H) at the concentrations above the pre-CMC. Catalytic activity of poly(SUA-H) on the acid hydrolyses of sucrose and p-nitrophenyl acetate, PNPA, was examined. For the hydrolysis of sucrose in water, the catalytic activity of poly(SUA-H) was slightly lower than that of hydrochloric acid and the catalysis followed an ordinary second-order kinetics. For the hydrolysis of PNPA in ethanol-water mixture (1:1 in vol.), the catalytic activity was slightly higher than that of hydrochloric acid, although the catalysis seemed to follow an ordinary second-order kinetics. For the hydrolysis of PNPA in water, however, catalytic activity was found to be considerably higher than those of hydrochloric acid and low molecular weight analog of poly(SUA-H). The reaction rate showed a saturation phenomenon with increasing concentration of poly(SUA-H), although it increased proportionally with increasing concentration of PNPA in the examined range. Lineweaver-Burk plots of the kinetic data showed good straight lines, which indicated that the catalysis followed a Michaelis-Menten type kinetics. These results can be explained by hydrophobic interactions of the catalyst with the substrate.