Glycols are a group of chemicals with a wide range of industrial uses. Antifreeze, resin production, heat transfer fluids and various industrial formulations are among the main areas where glycols appear. The three most commonly encountered members of this group are monoethylene glycol (MEG), diethylene glycol (DEG) and monopropylene glycol (MPG). Although their names are similar, these three products have different structures and different applications.
What is a glycol?
Glycol is the general name for alcohols with two hydroxyl (-OH) groups in the molecule. This structure gives glycols properties such as miscibility with water, moisture retention and a low freezing point. Glycols are usually colourless, odourless or faintly scented, syrupy liquids.
Monoethylene glycol (MEG)
- Other names: ethylene glycol, ethane-1,2-diol
- CAS number: 107-21-1
- Molecular formula: C2H6O2
MEG is the simplest member of the glycol group. It is used in antifreeze and coolants, in polyester resin and fibre production, and in various industrial formulations. For details, see our Monoethylene Glycol (MEG) page.
Diethylene glycol (DEG)
- Other name: 2,2′-oxydiethanol
- CAS number: 111-46-6
- Molecular formula: C4H10O3
DEG consists of two ethylene glycol units joined by an ether bond. It is hygroscopic, meaning it retains moisture. It is used in resins, inks and various industrial formulations. For details, see our Diethylene Glycol (DEG) page.
Monopropylene glycol (MPG)
- Other names: propylene glycol, 1,2-propanediol
- CAS number: 57-55-6
- Molecular formula: C3H8O2
MPG is a propylene-based glycol. It is used in resin and coating formulations, heat transfer fluids and various industrial applications. For details, see our Monopropylene Glycol (MPG) page.
Key differences
- Structure: MEG is the simplest glycol; DEG consists of two ethylene glycol units; MPG is propylene-based.
- Molecular size: DEG is a larger molecule than MEG; this difference affects properties such as boiling point and viscosity.
- Applications: MEG stands out in antifreeze and polyester production, DEG in resins and humectant applications, and MPG in resin, coating and heat transfer applications.
Choosing the right glycol
The choice of glycol depends on the requirements of the application. The process in which the product will be used, the physical properties needed and application-specific technical requirements are decisive. Some applications can only use a particular glycol, so the requirements of the application must be checked before considering one product in place of another.
Handling precautions
The instructions in the safety data sheet (SDS) should be followed in the transport, storage and use of glycols. Products should be stored in closed containers under suitable conditions and labelled. Glycols are products that should not be mixed up; storing each product separately with its own label is recommended. For general information, see our article Storage and Transport of Industrial Solvents.
Points to watch when choosing a glycol
Because the names MEG, DEG and MPG are similar, orders can get mixed up. It is therefore recommended to state the full chemical name and CAS number alongside the abbreviation: 107-21-1 for MEG, 111-46-6 for DEG and 57-55-6 for MPG. Comparing the packaging label with this information on receipt of goods also helps ensure the right product is used.
Which glycol suits your application should be assessed according to its technical requirements and the relevant regulations. If you share your application, we will assess your request accordingly.
Frequently asked questions
Are MEG and ethylene glycol the same thing?
Yes. Monoethylene glycol (MEG) and ethylene glycol refer to the same product.
Are MPG and propylene glycol the same?
Yes. Monopropylene glycol (MPG), propylene glycol and 1,2-propanediol refer to the same product.
Can glycols be used interchangeably?
Usually not. Each glycol has a different structure and properties; the requirements of the application should be checked.
Conclusion
Although their names are similar, MEG, DEG and MPG are different glycols in structure and applications. For details, see our Solvents page, and send your needs via the quote form. Packaging, quantity and quality are clarified in the quote.