“Exhaustive” Baeyer-Villiger Oxidation of Poly(Methyl Vinyl Ketone) and Its Copolymers

Poly(vinyl acetate) and its copolymers represent an important class of commodity polymers. However, the preparation of copolymers of vinyl acetate (VAc) and more activated monomers (MAMs) via copolymerization is greatly restricted due to their disparate reactivities. Issues relating to reactivity ratios remain a fundamental challenge in copolymerization. Herein, we describe a post-polymerization modification approach using poly(methyl vinyl ketone-co-MAM)s as substrates to access synthetically challenging poly(VAc-co-MAM)s. Although the direct translations of existing small-molecule Baeyer-Villiger (BV) protocols into a post-polymerization modification method failed, a mechanism-guided multi-parameter optimization on polymer substrates disclosed a set of unique “exhaustive” BV protocols which enabled a nearly quantitative functionalization without obvious chain scission or cross-linking. Furthermore, a one-pot copolymerization/“exhaustive” BV post-modification procedure was developed to produce such copolymers in a convenient and scalable manner. This user-friendly methodology is able to access diverse poly(VAc-co-MAM)s including both statistical and narrow-dispersed block copolymers and could greatly facilitate the exploration of applications with such materials.

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“Exhaustive” Baeyer-Villiger Oxidation of Poly(Methyl Vinyl Ketone) and Its Copolymers

10.33774/chemrxiv-2021-2b35c-v2 ◽

2021 ◽

Author(s):

Pengfei Ma ◽

Christopher M. Plummer ◽

Luo Wenjun ◽

Jiyan Pang ◽

Yongming Chen ◽

...

Keyword(s):

Block Copolymers ◽

Small Molecule ◽

Chain Scission ◽

Side Reactions ◽

One Pot ◽

Methyl Vinyl ◽

Modification Procedure ◽

Post Modification ◽

User Friendly ◽

Villiger Oxidation

The development of “exhaustive” (nearly quantitative) post-modification reactions relies heavily on the efficiency of their corresponding small-molecule protocols. However, the direct translation of existing small-molecule protocols into post-polymerization modifications were often troublesome due to undesired side reactions. For example, the development of an “exhaustive” BaeyerVilliger (BV) post-modification using existing small-molecule BV protocols suffered from a lack of reactivity or significant chain scission. Herein, we demonstrate that a careful re-optimization of a small-molecule transformation on a polymer substrate allowed us to overcome such challenges, thereby enabling an “exhaustive” BV post-polymerization modification. Furthermore, a one-pot copolymerization/“exhaustive” BV post-modification procedure was developed to produce copolymers of vinyl acetate (VAc) and more activated monomers (MAMs) in a convenient and scalable manner. This user-friendly methodology provides a general access to synthetically challenging poly(VAc-co-MAM)s including both statistical and narrow-dispersed block copolymers and could greatly facilitate the exploration of applications with such materials.

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Chain Scission in the Oxidation of Polyisoprene

Rubber Chemistry and Technology ◽

10.5254/1.3535152 ◽

1977 ◽

Vol 50 (2) ◽

pp. 373-396 ◽

Cited By ~ 30

Author(s):

J. L. Morand

Keyword(s):

Natural Rubber ◽

Chain Scission ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Alkoxy Radical ◽

Methyl Vinyl ◽

Protective Agents ◽

Volatile Products ◽

A Chain ◽

Oxidation In Air

Abstract The composition of the mixture of volatile products formed during the oxidation in air of natural rubber or synthetic cis-polyisoprene in the raw state was investigated in order to obtain further information on the mechanism of chain scission. An important observation was made: in order to obtain, by means of gas chromatography, the peaks of all the constituents, a completely anhydrous solution of the trapped mixture must be used. If the water liberated by the oxidized polyisoprene is present, the peaks of some constituents do not appear. By removing this difficulty, four new less volatile compounds which could result from chain scission were detected on heating extracted polyisoprenes which do not contain protective agents. The concentrations of these four compounds are similar to those of levulinaldehyde, methacrolein, or methyl vinyl ketone, and the structures which were identified correspond to a γ-substituted γ-butyrolactone, a primary γ-ketol, and probably a tertiary γ-aldol and a secondary γ-ketol. These components could arise from a chain scission between two isoprene units, due to a β-scission process of an alkoxy radical. Natural rubber or synthetic polyisoprene which contain protective agents give off mainly the lactone and the tertiary γ-aldol, but levulinaldehyde is produced in small amounts, and methacrolein and methyl vinyl ketone are absent.

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