Acetal Metathesis: Mechanistic InsightThis research was supported by the National Science Foundation (CHE-0848236 and CHE-1607263) and the University of Florida.
Received: 31 January 2019
Accepted after revision: 25 April 2019
13 May 2019 (online)
Published as part of the Cluster Metathesis beyond Olefins
The origins and recent applications of acetal metathesis are discussed in the context of synthesizing polyacetals via acetal metathesis polymerization (AMP). A kinetic study of the acid-catalyzed acetal metathesis reaction suggests the rate = k[H+][acetal]2, with MeOCH2OMe and EtOCH2OEt interchanging to yield MeOCH2OEt, achieving the statistical 1:2:1 equilibrium distribution in 4 hours at 80 °C and in 1 hour at 90 °C. Upon heating 1,10-decanediol and diethoxymethane, polydecylene acetal is formed with sequential distillation of ethanol, followed by diethoxymethane. A full mechanism for this polymerization is proposed, which begins with a transacetalization sequence to convert the diol into a bisacetal, followed by acetal metathesis to yield a high-molecular-weight polymer.
Key wordsacetal - metathesis - transacetalization - polyacetal - acid catalysis - kinetic study - nucleophilicity
References and Notes
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