Synthesis, characterization and controlled release behaviour of adducts from chloroacetylated cellulose and α-naphthylacetic acid

• Published in: Reactive & functional polymers Vol. 39; no. 2; pp. 179 - 187
• Main Authors: Martin, A.I., Sánchez-Chaves, M., Arranz, F.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.02.1999; Elsevier Science
• Subjects: Applied sciences; Cellulose and derivatives; Cellulose–α-naphthylacetic adducts; Chloroacetylated cellulose; Exact sciences and technology; Heterogeneous hydrolytic behaviour; Natural polymers; Physicochemistry of polymers; Relative reactivity; Relative reactivity; Chloroacetylated cellulose; Heterogeneous hydrolytic behaviour; Cellulose–α-naphthylacetic adducts; Regioselectivity; Control release polymer; Cellulose; Experimental study; Naphthalene derivatives; Esterification; Hydrolysis; Homogeneous reaction; Chemical modification; Preparation; Carboxylate; Acyl chloride; Plant growth substance; Cellulose organic ester; Kinetics; Chlorine containing polymer; Rate constant; Nucleophilic substitution; Release; Heterogeneous reaction
• ISSN: 1381-5148
• DOI: 10.1016/S1381-5148(97)00180-6

Celluloses partially functionalized with chloroacetate groups were obtained by reaction of cellulose with chloroacetyl chloride using pyridine as catalyst and the dimethylacetamide/LiCl system as solvent. 13C NMR spectra at 75.4 MHz of partially modified cellulose with chloroacetate groups were studied in order to evaluate the selectivity of the reaction of cellulose with chloroacetyl chloride in the homogeneous phase. Analysis of the spectra of ring carbons in the anhydroglucose units shows that the reactivity of the individual hydroxyl groups decreases in the order C-6>C-3>C-2. The coupling of α-naphthylacetic acid to cellulose 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]-7-undecene. High degrees of modification were obtained by both methods. However, the esterification reaction is somewhat more efficient in the case of the potassium salt. The kinetic results were consistent with a second-order reaction. The hydrolysis in the heterogeneous phase of cellulose–α-naphthylacetic acid adducts showed that the release of the bioactive compound is dependent on the hydrophilic character of the adduct as well as on the pH value of the medium.