COENZYME MODELS - 32. CATALYTIC ACTIVITY OF POLYMER-BOUND THIAZOLIUM IONS AS ESTIMATED BY FLAVIN TRAPPING TECHNIQUE.

In the reported experiments, three thiazolium-containing polymers, Th-7, Th-33, and Th-18-Py left bracket where Th-x and Py mean x mol% thiazolium unit and pyridinium unit (54 mol%), respectively right bracket , were synthesized from partially p-chloromethylated polystyrene. The catalytic activities of these polymer catalysts in acyloin condensation of aldehydes and decarboxylation of alpha -keto acids were estimated kinetically by oxidative trapping of the key intermediate by flavin (flavin-trapping technique). In aqueous solution at 30 degree C, the catalytic activity of Th-18-Py and Th-33 in condensation of p-chlorobenzaldehyde was comparable with that of the cationic-micelle-bound thiazolium ion, whereas Th-7 and a monomeric thiazolium compound (N-benzylthiazolium bromide) scarcely exhibited any catalytic activity. The catalysis of the polymer-bound thiazolium ions was sensitively suppressed by increased ionic strength.