Synlett
DOI: 10.1055/s-0037-1611833
cluster
© Georg Thieme Verlag Stuttgart · New York

Acetal Metathesis: Mechanistic Insight

Alexander G. Pemba
,
The George and Josephine Butler Laboratory for Polymer Research, Department of Chemistry, 165 Buckman Drive, University of Florida, Gainesville, FL, 32611-7200, USA   Email: miller@chem.ufl.edu
› Author Affiliations
This research was supported by the National Science Foundation (CHE-0848236 and CHE-1607263) and the University of Florida.
Further Information

Publication History

Received: 31 January 2019

Accepted after revision: 25 April 2019

Publication Date:
13 May 2019 (eFirst)

Published as part of the Cluster Metathesis beyond Olefins

Abstract

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.

Supporting Information

 
  • References and Notes

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  • 28 Protocol for the Bisacetal SynthesisA 1 liter round-bottom flask was charged with 17.43 g (0.100 mol, 1 equiv) of 1,10-decanediol, 208.30 g (2.00 mol, 20 equiv) of diethoxymethane, 0.190 g (1 mol%) of para-toluenesulfonic acid, and 100 mL of toluene. Ethanol was exhaustively removed via distillation over 24 h, followed by refluxing for 48 h. Workup, as described in the Supporting Information, afforded the bisacetal as a colorless oil in 72% yield (21.03 g).