The Effect of hydrophobic‐lipophilic interactions on chemical reactivity. 12. Mechanistic investigations of NaCMA‐catalyzed hydrolysis of esters

The dependence of the catalytic efficiencies of sodium carboxymethylamylose (NaCMA) for the hydrolysis of N‐lauryl‐3‐acetoxypyridinium iodide ( 1 ) and p ‐nitrophenyl dodecanoate ( 3 ) on its degree of substitution (D. S. = 0·00, 0·12, 0·18, 0·24, 0·29 and 0·35) and on the pH values of the solutions (pH = 7·32, 7·80, 8·10 and 9·30) have been studied. At fixed D. S. values, the observed hydrolysis rates of 1 and 3 increase with increasing concentrations of NaCMA and follow saturation kinetics. At fixed concentration of NaCMA, the rates increase with decreasing D. S. values until they reach maxima at D. S. = 0·00. Furthermore, at any D. S. value the catalytic efficiency increases with increasing pH values of the solutions. All these results indicate that the hydroxyl groups are actually the principal catalyzing groups.