Controlled activity polymers. X synthetically tailored monomers and copolymers with hydrolytically-labile pendent esters of allelopathic phenols

Abstract

Monomers containing hydrolytically-labile ester linkages to allelopathic compounds: phenol, 2-isopropylphenol, 2,6-diisopropylphenol, 2-hydroxybenzoic acid and naphthoic acid were synthesized for incorporation into hydrophilic copolymers. Phenyl acrylate (PA), 2-isopropylphenyl acrylate (IPPA), 2,6-diisopropylphenyl acrylate (DIPPA), 2-acryloxybenzoic acid (2ABA) and 2-acryloxy-1-naphthoic acid (2ANA) were synthesized by esterification of the parent phenol with acryloyl chloride. These monomers were subsequently copolymerized with acrylic acid (AA) using AIBN as initiator in benzene or tetrahydrofuran at 70°C. PA was copolymerized with acrylamide (AM) and N-vinylpyrrolidinone (NVP) using AIBN in tetrahydrofuran and benzene, respectively, at 70°C. Copolymer compositions were determined by 1H NMR, 13C NMR, FTIR and UV-VIS spectroscopy. The copolymerization reactivity ratios were determined from 1H NMR data using Fineman-Ross (F-R), Kelen-Tudos (K-T) and nonlinear least-squares (NLS) methods. Copolymer statistical data were determined from K-T reactivity ratios. The resulting water soluble copolymers are potentially useful as plant growth regulators through the hydrolytic release of phenolic and naphthoic compounds. Selected polymers from these structurally-tailored series were chosen for controlled release studies in aqueous media reported in the subsequent paper of the series.