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Polymer-supported catalysts of several kinds, including /3-cyclodextfin (P-CD), fl-cyclodextrin-diethylenetriamine (P-CD-DETA), and fl-cyclodextrin-N-methylhydroxamate (P-CD-NMHA)-containing polymers, as well as their corresponding metal complexes, were synthesized and examined as catalysts for the hydrolysis of phosphate esters. The kinetic measurements were performed in a phosphate buffer (0.05 M, pH 8.2) at a temperature of 25.0 4-0.1 o C. Each kinetic run was initiated on introducing ester stock solution (0.13 ml) containing diphenyl p-nitrophenyl phosphate (DPPNPP) in dioxane (0.010 M). The rate of hydrolysis of DPPNPP was evaluated by measuring the absorbance of liberated p-nitrophenol at 402 run. The dissociation constants between DPPNPP and the polymers P-CD, P-CD-DETA and P-CD-NMHA obtained from Eadie-type plots were 16.8, 16.4 and 8.0 (x 10 -3 M) and the acceleration factors were 1.5, 2.8 and 8.6 respectively. Hence P-CD-NMHA is the most promising catalyst. The activation parameters, preexponential factor (A) and activation energy using P-CD-NMHA as catalyst, are A = 1.2 x 10 9 min -1 and E~ = 43 kJ/mol respectively; the latter was about 12 kJ/mol lower than the activation energy of spontaneous hydrolysis. The results indicate that the catalytic power of P-CD-NMHA may reflect the combined behavior of molecular recognition and nucleophilicity.

Three kinds of new chelating resin containing /?-hydroxydithiocinnamic acid, ethyl /~-hydroxydithiocinnamate and N-(hydroxymethyl)-thioamide functional groups were synthesized. Cu(II), Cd(II) and Hg(II) were used as complex forming metal ions. By varying the combination of metal ion and chelating resin, a great variety of separation systems could be realized. For the on-line trace enrichment of 2-mercaptobenzimidazole, the copper-loaded N-(hydroxymethyl)-thioamide concentration column was found most suitable. UV detection at 300 nm was used. The detection limit was 0.2 ng/g. A 10 ml sample was found to be sufficient to attain the described sensitivity, and linear relationship was obtained-in the range of 0.75 ng/g to 12 ng/g. The best separation of the thiol compound mixture thioglycolic acid, methionine, cysteine and 2mercaptoethanol was obtained with coppeMoaded ethyl/~hydroxydithiocinnamate resin; UV absorbance detection was at 215 nm.

A histidine-containing polymer was synthesized in which the amino group of the histidine was attached chemically via an azide coupling method to the carboxylic acid of Amberlite IRC-50. The resultant polymer was applied as a catalyst for hydrolysis of p-nitrophenyl acetate (PNPA). PNPA in aqueous solution was hydrolyzed at 25°C with a phosphate buffer (pH 7.8). The observed kinetics obeyed Michaelis-Menten kinetics. The reaction rates at various temperature were measured. The activation parameters, preexponential factor (A) and activation energy (E,), were 6.64 X 10e4 min-' and 37.5 kJ mol-' respectively. At a pH of the medium greater than 7.8, the reaction rate remained almost constant (k,, = 0.024 min-'> and seemed to be controlled by the rate of diffusion of PNPA from the bulk solution into the catalytically active site at the resin channel surface. For catalysed hydrolysis, the effect of ionic strength in solution demonstrated that bifunctional cooperation between adjacent histidine groups existed through the nucleophilicity of nitrogen. The effects of metal ions and aspartic acid or serine on hydrolysis were also investigated.