Dimethoxyethane

Dimethoxyethane, also known as glyme, monoglyme, dimethyl glycol, ethylene glycol dimethyl ether, dimethyl cellosolve, and DME, is a clear, colorless, aprotic, and liquid ether that is used as a solvent. Dimethoxyethane is highly soluble in water.

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Dimethoxyethane is often used as a higher boiling alternative to diethyl ether and THF. Dimethoxyethane forms chelate complexes with cations and acts as a bidentate ligand. It is therefore often used in organometallic chemistry like Grignard reactions, hydride reductions, and palladium catalyzed reactions like Suzuki reactions and Stille coupling. Dimethoxyethane is also a good solvent for oligo- and polysaccharides.

The lowest energy form of dimethoxy ethane in the gas phase is the gauche, rather than the anti conformer

Production

Monoglyme be manufactured by a number of methods:^[1]

• via the Williamson ether synthesis — reacting the sodium salt of 2-methoxyethanol (previously prepared by reaction with sodium) with chloromethane:

2 CH₃OCH₂CH₂OH + 2 Na → 2 CH₃OCH₂CH₂ONa + H₂↑

CH₃OCH₂CH₂ONa + CH₃Cl → CH₃OCH₂CH₂OCH₃ + NaCl

• via the alkylation of 2-methoxyethanol with dimethyl sulfate
• by the cleavage of ethylene oxide in presence of dimethyl ether. This reaction is catalyzed by Lewis acids (e.g. boron trifluoride or its complex with dimethyl ether). This route is not particularly selective and produces di- tri, tetra- and other glymes as a by-products. The reaction mixture is separated by distillation:

CH₃OCH₃ + CH₂CH₂O → CH₃OCH₂CH₂OCH₃

Uses

Together with a high-permittivity chemical (eg. propylene carbonate), dimethoxyethane is used as the low-viscosity component of the solvent for electrolytes of lithium batteries.

References

1. ^ Dimethoxyethane