Study on TEMPO-mediated selective oxidation of hyaluronan and the effects of salt on the reaction kinetics

2,2,6,6-Tetramethyl-1-piperidinyloxy radical (TEMPO)-mediated oxidation of hyaluronan was studied at pH 10.2. and temperature of 0 degrees C with NaOC l as the primary oxidant. As with other polysaccharides, a high selectivity of oxidation was observed. The degradation of the polymer was essentially caused by the oxidation process. The primary oxidant and the pH of the reac tion mixture did not alter the molecular weight of hyaluronan during oxidat ion. The kinetics of the oxidation process was investigated at different co ncentrations of reactants and the inorganic salts, NaBr, NaCl, and Na2SO4. An increase in the salt concentration in the mixture causes a major decreas e in the rate of the oxidation, and this decrease is independent of the nat ure of the salt. (C) 2000 Elsevier Science Ltd. All rights reserved.