Poly(vinyl alcohol) functionalized by chloroacetate groups. Coupling of bioactive carboxylic acids

✍ Scribed by Felix Arranz; Eva María Bejarano; Manuel Sanchez-Chaves

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 466 KB
• Volume: 195
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1994.021951205

✦ Synopsis

Abstract

Poly(vinyl alcohol) (PVAL) functionalized with chloroacetate groups was obtained by reaction of PVAL with chloroacetyl chloride using pyridine as catalyst and N‐methyl‐2‐pyrrolidone as solvent. The structure of the modified polymers was determined by means of IR, ^1^H and ^13^C NMR spectroscopies. The coupling of model bioactive carboxylic acids (1‐naphthylacetic acid and 6‐methoxy‐α‐methyl‐2‐naphthaleneacetic acid (naproxen)) to PVAL functionalized with chloroacetate groups was carried out by reaction with their potassium salts or directly in the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU). High degrees of modification were obtained in the reaction with the potassium salts. However, the esterification reaction is somewhat more efficient in the case of the potassium salt of 1‐naphthylacetic acid. The kinetic results were consistent with a second‐order reaction, and the activation energy in the reaction with the potassium salt of 1‐naphthylacetic acid was found to be 73,2 kJ/mol. The reaction of PVAL with 1‐naphthylacetic acid and naproxen in the presence of DBU showed deviation from second‐order kinetics, which may be a consequence of some steric effects. The hydrolysis in the heterogeneous phase of PVAL‐1‐naphthylacetic acid and PVAL‐naproxen adducts showed that the release of the bioactive compound from tablets is dependent on the hydrophilic character of the adduct as well as on the pH value of the medium.