Short-chain oxymethylene dimethyl ethers (OMEs) (molecular formula: H3CO-(CH2O)n-CH3, where n = 3-5) have previously been studied as diesel-like fuels and fuel additives. OMEs can be produced from sustainably sourced methanol, and tests indicate that they are neither genotoxic nor mutagenic. In this report, their potential as solvents has been investigated to expand the bio-derived solvent space. According to traditional solvatochromic parameters, a commercial mixture of OME3-5 and its individual components (OME3, OME4, and OME5) have solvation properties similar to problematic industrial ether solvents such as 1,4-dioxane. Peroxide formation, one of the chief dangers of classical ether solvents, was found to occur much more slowly in OMEs than in conventional solvents such as tetrahydrofuran (THF), demonstrating an improved safety profile. The commercial OME3-5 mixture was found to be broadly miscible with organic solvents but immiscible with water, suggesting potential application in aqueous extractions. It performed well in the dissolution of polystyrene and removal of paints and coatings, indicating OME3-5 may suitable to replace dichloromethane in polymer recycling, polymer welding, and cleaning applications. To further demonstrate applicability as a solvent, this mixture was shown to facilitate a model Suzuki coupling reaction at rates similar to cyclopentyl methyl ether, which is currently marketed as a green ether. Finally, OME3-5 proved a suitable solvent for enzymatic polymerization, giving high yields, moderately high degrees of polymerization, and remarkably narrow dispersity values.
Bibliographical note© 2019 American Chemical Society
- green solvents
- polymer dissolution