Glycol Ethers, High-Purity Solvents

Diethylene Glycol Monomethyl Ether (MDG)

Diethylene Glycol Monomethyl Ether (MDG), also known by the IUPAC name 2-(2-methoxyethoxy)ethanol, is a versatile organic solvent belonging to the E-series glycol ether family. It is a clear, colorless, hygroscopic liquid characterized by a mild, ether-like odor. MDG’s chemical structure integrates both ether and alcohol functional groups, providing a unique “dual-solvency” nature. This allows the compound to act as an effective bridge between polar substances, such as water, and non-polar organic compounds.

MDG is highly valued in industrial chemistry for its high boiling point, low volatility, and excellent thermal stability. These properties make it an ideal choice for high-temperature processing and formulations requiring slow evaporation rates. However, it is important to note that MDG is classified as a reproductive toxicant (Category 2) under GHS standards, requiring stringent safety protocols and specialized handling. Despite regulatory oversight, its efficacy as a coupling agent and freezing point depressant remains critical in the aviation, automotive, and coatings industries.

Attributes

Key Features and Benefits

Exceptional Solvency: Demonstrates powerful dissolving capabilities for various resins, oils, nitrocellulose, and dyes, ensuring homogeneous formulations.
Universal Miscibility: Completely miscible with water and a broad spectrum of organic solvents, offering significant flexibility in solvent-borne and aqueous systems.
Low Evaporation Rate: Its high boiling point ensures it remains in the matrix longer, which enhances the flow, leveling, and gloss of surface coatings.
Effective Coupling Agent: Functions as an intermediate to stabilize mixtures of incompatible fluids, preventing phase separation in complex chemical products.
High Flash Point: Compared to shorter-chain ethers, MDG offers a higher flash point, reducing the risk of accidental ignition during high-temperature industrial processes.

Specifications

Technical Highlights

Molecular Formula: C₅H₁₂O₃ (CAS No. 111-77-3).
Molecular Weight: 120.15 g/mol.
Boiling Point: Approximately 194°C (381°F) at 760 mmHg.
Flash Point: 93°C (199°F) via Closed Cup method.
Vapor Pressure: Extremely low at 0.2 mmHg at 20°C, minimizing VOC emissions in stationary applications.
Specific Gravity: 1.021 at 20°C.
Viscosity: 3.48 mPa·s at 20°C, providing effective thinning properties for high-viscosity resins.
Safety Profile: Identified as a suspected reproductive toxicant (H361d); technical users must ensure adequate local exhaust ventilation and appropriate skin/respiratory protection.