Dimethyl Carbonate (DMC, CAS 616-38-6): Uses of a Green Solvent

What Is Dimethyl Carbonate (DMC, CAS 616-38-6)?

Dimethyl carbonate (DMC) is the simplest organic carbonate ester, with the molecular formula C3H6O3 and a molecular weight of 90.08 g/mol. Its CAS Registry Number is 616-38-6 and its EINECS number is 210-478-4. DMC is a colorless, transparent liquid with a mild sweet odor. It has a boiling point of about 90.3 °C, a melting point of about 2 to 4 °C, a density of about 1.07 g/cm3, and a flash point of about 18 °C (closed cup). It is miscible with most organic solvents, has low toxicity, and biodegrades readily, which is why it is described as a green solvent.

Key Physical and Chemical Properties

What Is DMC Solvent Used For?

Coatings, Adhesives, and Cleaning

DMC dissolves a wide range of resins, polymers, and oils, making it a replacement candidate for more hazardous solvents in coatings, adhesives, ink, and cleaning formulations. Its low toxicity and easy biodegradation reduce the environmental burden compared with chlorinated or aromatic solvents.

Lithium-Ion Battery Electrolytes

DMC is a common co-solvent in lithium-ion battery electrolytes, where it lowers the viscosity of the electrolyte and improves low-temperature performance. Demand from consumer electronics, electric vehicles, and energy storage systems is a major growth driver for DMC.

Organic Synthesis Reagent

In chemical synthesis, DMC acts as a methylating and carbomethoxylating agent that can replace dimethyl sulfate and phosgene in many reactions. These greener routes are used to produce anisole derivatives, carbonates, carbamates, and pharmaceutical intermediates.

Other Applications

DMC is studied and used as a fuel oxygenate additive, as a solvent in paint stripping and degreasing, and as an intermediate in the synthesis of polycarbonate by transesterification routes.

Why DMC Is Considered an Environmentally Friendly Solvent

Compared with many traditional solvents, DMC has low acute toxicity, does not accumulate in organisms, and breaks down to carbon dioxide and methanol under environmental conditions. Its use avoids the chlorinated waste streams associated with solvents such as dichloromethane. However, DMC is still a flammable liquid with a flash point near room temperature, so fire safety measures are required wherever it is handled or stored.

Quality and Handling Considerations

Commercial DMC is specified by purity, water content, color, and density. Purity is measured by gas chromatography, water by Karl Fischer titration per ASTM E203, color by the Pt-Co scale per ASTM D1209, and density by ASTM D4052. Because DMC is flammable and can decompose on heating, store it in grounded, sealed containers away from ignition sources, strong acids, and strong bases, and use local ventilation during transfer.

Frequently Asked Questions

What does DMC stand for in chemistry? DMC stands for dimethyl carbonate, an organic carbonate ester with the formula C3H6O3 and CAS number 616-38-6.

Is DMC the same as dichloromethane? No. Dichloromethane (DCM) is a chlorinated solvent with CAS 75-09-2, while dimethyl carbonate (DMC) is a non-chlorinated carbonate ester with CAS 616-38-6. They differ completely in structure, toxicity, and regulatory profile.

Is dimethyl carbonate toxic? DMC has low acute toxicity compared with many industrial solvents, but it is still a flammable liquid and can irritate the eyes and respiratory tract at high vapor concentrations. Good ventilation and standard PPE are required.

Why is DMC used in lithium-ion batteries? DMC is used as a co-solvent in the electrolyte to reduce viscosity and improve ion transport and low-temperature performance, which helps batteries deliver stable capacity.

Can DMC replace phosgene and dimethyl sulfate in synthesis? In many methylation and carbomethoxylation reactions, yes. DMC offers a less hazardous alternative, although reaction conditions, catalysts, and selectivity must be revalidated for each process.

How should DMC be stored? Store DMC in sealed, grounded containers in a cool, dry, well-ventilated area away from ignition sources, strong acids, and strong bases. Keep the container closed when not in use to prevent moisture and contamination.