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Updated: Mar 13, 2026

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes
Published on: November 21, 2017
Alternating Sequence Control for Carboxylic Acid and Hydroxy Pendant Groups by Controlled Radical Cyclopolymerization
Makoto Ouchi1,2, Marina Nakano1, Tomoya Nakanishi1
1Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto, 615-8510, Japan.
Abstract:
By utilizing features of the hemiacetal ester (HAE) bond: easy formation from vinyl ether and carboxylic acid and easy cleavage into different functional groups (-COOH and -OH), we achieved control of the alternating sequence of two functional pendant groups of a vinyl copolymer. Methacrylate- and acrylate-based vinyl groups were connected through HAE bonds to prepare a cleavable divinyl monomer, which was cyclo-polymerized under optimized conditions in a ruthenium-catalyzed living radical polymerization. Subsequent cleavage of the HAE bonds in the resultant cyclo-pendant led to a copolymer consisting of alternating methacrylic acid and 2-hydroxyethyl acrylate units as analyzed by 13 C NMR spectroscopy. The alternating sequence of -COOH and -OH pendants specifically provided a lower critical solution temperature (LCST) in an ether solvent, which was not observed with the random copolymer of same composition ratio.
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Acid Halides to Carboxylic Acids: Hydrolysis
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic...

