At a natural gas processing plant, water is the enemy of the pipeline; at a polyester resin producer, it is the building block that extends the molecular chain. The curious part is that the hero of both scenarios comes from the same chemical family — two siblings born from one process. Diethylene glycol (DEG) and triethylene glycol (TEG) are inevitable co-products of monoethylene glycol (MEG) manufacturing, yet the phrase "by-product" badly undersells their value. Choosing the right grade, the right CAS number and the right supplier directly determines both the performance of your formulation and your landed cost.
What Is Diethylene Glycol (DEG), and How Is It Related to TEG?
Diethylene glycol (DEG) is a colorless, odorless, hygroscopic, viscous liquid with the chemical formula C₄H₁₀O₃ and CAS number 111-46-6. It is fully miscible with water and carries two hydroxyl (–OH) groups plus one ether bridge in its molecule. Triethylene glycol (TEG), formula C₆H₁₄O₄ and CAS number 112-27-6, is one ethylene-oxide unit longer than DEG and therefore a higher-molecular-weight glycol derivative.
The cleanest way to understand these two products is to look at where they come from. When ethylene oxide reacts with water, MEG (monoethylene glycol) forms first. The reaction does not stop there: part of the MEG reacts with additional ethylene oxide to become DEG, and part of the DEG goes on to form TEG. In other words, DEG and TEG are the co-product streams of MEG production. As the chain grows longer across these three siblings from the same column, their properties shift in a predictable, systematic way.
If you want to understand the parent product itself, our guide on what monoethylene glycol is covers MEG and its core applications in detail. Here, the focus is on the two chemicals that live in MEG's shadow but play critical industrial roles: DEG and TEG.
What does chain length actually change?
In the ethylene glycol family, every additional ethylene-oxide unit lengthens the molecule and shifts three properties in a foreseeable direction:
- Molecular weight rises (MEG 62 → DEG 106 → TEG 150 g/mol).
- Boiling point increases while volatility drops.
- Hygroscopic behavior changes; TEG holds water more "persistently" and can be regenerated.
These three trends explain how every application below is distributed. When choosing a glycol, "which one is better" is the wrong question. The right question is "which chain length suits my process."
MEG vs DEG vs TEG Comparison Table
The question we hear most often in the field is the concrete specification difference between the three glycols. The table below summarizes the baseline values you can use as a reference in supply and formulation decisions. (Values are typical literature ranges; for exact figures, always consult the product COA.)
| Property | MEG (Monoethylene Glycol) | DEG (Diethylene Glycol) | TEG (Triethylene Glycol) |
|---|---|---|---|
| CAS No. | 107-21-1 | 111-46-6 | 112-27-6 |
| Chemical formula | C₂H₆O₂ | C₄H₁₀O₃ | C₆H₁₄O₄ |
| Molecular weight (g/mol) | ~62 | ~106 | ~150 |
| Boiling point (°C) | ~197 | ~245 | ~285 |
| Freezing / pour point (°C) | ~ -13 | ~ -8 | ~ -7 |
| Density (20 °C, g/cm³) | ~1.113 | ~1.118 | ~1.125 |
| Viscosity (20 °C, mPa·s) | ~20 | ~35 | ~49 |
| Hygroscopicity | High | Medium–high | High (regenerable) |
| Acute oral toxicity | Moderate | High (hazardous) | Comparatively low |
| Leading use | Antifreeze, PET | Resins, plasticizers, humectant | Gas dehydration, humectant |
The pattern in the table is clear: as the chain lengthens, molecular weight, boiling point and viscosity all rise in an orderly way. That is why DEG sits as a mid-weight "bridge" molecule, while TEG positions itself as a high-boiling, low-volatility "drying agent." You can see the same selection logic applied to MEG versus MPG (monopropylene glycol) in our MEG vs MPG comparison; the safety and food-suitability discussion there also helps explain why DEG is strictly a non-food product.
Diethylene Glycol (DEG) Uses
The industrial value of DEG comes from the versatility granted by its two hydroxyl groups and its moderate molecular weight. Here are the application areas we encounter most often in the field.
Unsaturated polyester resins (UPR)
One of the largest consumption areas for DEG is unsaturated polyester resin (UPR) production. It serves as a diol component in resin synthesis, giving the polymer chain flexibility and toughness. Partially replacing MEG with DEG makes the cured resin less brittle. These resins are widespread in glass-fiber-reinforced plastics, buttons, boat hulls and composite parts — many of which are high-value export goods.
Plasticizers
DEG is used as an intermediate in the production of various plasticizer esters (for example, diethylene glycol dibenzoate). These esters are added to PVC and adhesive formulations to impart flexibility to the material. Demand for such derivatives is continuous in the packaging and adhesive sectors, where consistent supply and documented purity are essential to keep production lines running.
Humectant and softening agent
Thanks to its hygroscopic nature, DEG works as a humectant in some industrial applications, drawing moisture from the surroundings to slow the drying of a material. It is also used for its softening effect in paper, cork and certain adhesive systems. Important warning: because DEG is toxic, it is never used in food, cosmetic or pharmaceutical humectant applications; for those uses, food-grade MPG is the correct choice. We cover this in detail in our guide on monopropylene glycol (MPG).
Brake fluids and industrial fluids
Its glycol-ether structure makes DEG a component in some brake fluid formulations and industrial heat-transfer fluids. Its high boiling point and water miscibility are desirable traits in these fluids. That said, brake fluids more often rely on higher glycol-ether derivatives; DEG typically appears as one component rather than the base.
Other applications
- Diol component in resin and alkyd paint systems,
- Solvent / co-solvent in certain formulations,
- Drying and gas-conditioning processes (more limited than TEG),
- Antifreeze blends (less common than MEG, but present in some low-cost formulations).
Triethylene Glycol (TEG) Applications
Because TEG is one unit longer than DEG, it exhibits a higher boiling point, lower vapor pressure and excellent hygroscopic behavior. These three properties define TEG's flagship application directly.
Natural gas dehydration (gas drying)
TEG's most iconic use is the dehydration of natural gas. Water vapor in natural gas causes corrosion, hydrate formation and flow problems in pipelines. In the absorption column, TEG contacts the gas stream and pulls the water onto itself.
The reasons TEG is ideal for this job are:
- High boiling point (~285 °C): In the regeneration column, water vaporizes at a lower temperature than TEG, so the glycol is easily re-concentrated.
- Low vapor pressure: Carry-over loss with the gas during processing is minimal.
- Thermal stability: It withstands repeated regeneration cycles.
In this cyclic process, TEG is reused many times, which makes it economical operationally. In the field, the most critical parameters for TEG units are the glycol's purity and water content.
Humectant and air disinfection
Because of its capacity to hold airborne moisture, TEG is used in air conditioning and humidity control applications. It has also been studied as a component in some air-disinfection systems for its effect on airborne microorganisms.
Plasticizer and resin
Like DEG, TEG is used in the production of plasticizer esters (for example, triethylene glycol bis-2-ethylhexanoate). It acts as a flexibility agent in vinyl and cellulosic systems.
Solvent and intermediate
As a high-boiling solvent, TEG can feature in printing inks, coatings and some cleaning formulations. It also serves as an intermediate in surfactant and polymer synthesis.
Key Differences Between DEG and TEG
When you place the two products side by side, the selection logic becomes clear. The comparison below summarizes which product has the advantage in which process.
| Decision criterion | DEG (CAS 111-46-6) | TEG (CAS 112-27-6) |
|---|---|---|
| Molecular weight | Lower (~106) | Higher (~150) |
| Boiling point | ~245 °C | ~285 °C |
| Volatility | Comparatively higher | Low (advantage) |
| Gas dehydration suitability | Limited | Industry standard |
| Resin / plasticizer | Common | Common |
| Acute oral toxicity | High (caution!) | Comparatively low |
| Typical unit cost | More economical | Higher |
In short: DEG stands out in resin, plasticizer and cost-sensitive humectant applications, while TEG is preferred in gas drying and applications that require low volatility and regenerable moisture capture. Both are water-miscible and hygroscopic, but the difference in chain length dictates how each behaves in the process.
Hygroscopicity and Boiling Point: The Two Properties That Drive Selection
The most common misconception when choosing glycol derivatives is confusing "hygroscopicity" with "moisture-holding permanence." All three glycols love water, but TEG is superior in cyclic processes because it can capture water and then release it in a controlled way. MEG also attracts water, but its lower boiling point means it cannot be regenerated as efficiently as TEG in gas drying.
The boiling-point difference translates directly into an operational advantage. TEG's ~285 °C boiling point makes separating water in the regeneration column easier while minimizing loss of the glycol itself. DEG's ~245 °C fits better with medium-temperature processes such as resin synthesis. This is precisely why a natural gas operator and a resin producer make fundamentally different glycol choices.
On the antifreeze side, we explain why MEG is the dominant product and the logic of freezing-point depression more fully in our MEG and antifreeze guide; that freeze–boil balance logic is also useful for understanding why DEG and TEG settle into different niches.
Toxicity, Storage and Safe Handling
The most critical dimension of using DEG and TEG correctly is safety, and here the two products diverge significantly.
DEG toxicity — never overlook it
Diethylene glycol (DEG) is seriously toxic if ingested. History includes poisoning incidents caused by DEG being mistakenly added to medicines and food products, which is exactly why this substance must be kept strictly away from food and pharmaceutical applications. When metabolized in the body, it shows toxic effects on the kidneys and nervous system. For this reason, DEG:
- Is never used in food, drug, cosmetic or oral products.
- Requires protection from skin and eye contact during industrial use.
- Calls for appropriate personal protective equipment (gloves, goggles) during processing.
TEG's acute oral toxicity is comparatively low, but that does not make it "food-grade"; both must be treated as industrial chemicals. Manufacturers who need a food or cosmetic humectant should turn to alternatives such as food-grade MPG rather than DEG.
Storage and labeling
Because glycols are hygroscopic, contact with humid air during storage causes water pickup, which degrades the purity and water-content specification. Therefore:
- Containers should be kept tightly closed and protected from moisture.
- Stainless steel or suitable plastic (HDPE) packaging is preferred.
- Store in a cool place away from direct sunlight and heat sources.
Follow GHS/CLP rules for chemical labeling and hazard communication, and request current MSDS and COA documents with every shipment. Although glycols are generally not classified as dangerous goods under ADR, internal safety procedures should always be applied. For export shipments, aligning documentation with the destination country's chemical-import requirements avoids costly customs delays.
Choosing the Right Grade and Supplier
With DEG and TEG, the "grade" difference determines the success of your process. Two products carrying the same CAS number can differ in water content, impurity profile and color (APHA). For example, water content and thermal stability are critical in TEG used for gas drying, while diol purity comes to the fore in DEG used for resin production.
Points to watch when selecting a supplier:
- COA (Certificate of Analysis): Every batch should document water content, purity, density and color values.
- MSDS: A current safety data sheet is essential for correct handling.
- Packaging flexibility: IBC, drum or bulk supply options to match your needs.
- Supply continuity: Stable delivery through the price swings that follow the MEG market.
For international buyers, the supply and logistics of glycol derivatives are tied directly to the import market and ethylene-oxide prices. DEG pricing is therefore not fixed; it varies with the MEG market, purity grade and packaging type. A good supplier offers not only the product but also the technical documentation, clear Incoterms and reliable delivery — the elements that make an export order predictable.
DEG and TEG Supply from Yüksek Kimya
At Yüksek Kimya, from our base in Bursa Kestel, Turkey, we provide wholesale supply of glycols and their derivatives to the automotive, textile, packaging, paint and coating, detergent and cosmetics sectors. We offer diethylene glycol (DEG) and triethylene glycol (TEG), along with our full glycol product group, backed by an ISO 9001, ISO 14001, ISO 45001 and GHP quality approach and supplied with MSDS and COA documentation.
For the grade suited to your process, packaging options (IBC / drum / bulk) and a current export quote, explore our glycols and derivatives product category and request a quote through our contact page with your product, quantity and technical requirements. Our team is ready with technical support to match the right glycol to the right application, and to align Incoterms and shipping documentation with your destination market. For samples, technical documents or shipment planning, you can also call us at +90 224 326 27 50.
Related reading
- What Is Monoethylene Glycol (MEG)? — MEG, the parent product of DEG and TEG, and its applications.
- MEG vs MPG: Which Glycol Goes Where? — Safety and food-suitability comparison for glycol selection.
- What Is Monopropylene Glycol (MPG)? — The non-toxic glycol alternative for food and cosmetic applications.
Frequently Asked Questions
What is the difference between diethylene glycol (DEG) and monoethylene glycol (MEG)?
DEG is a co-product formed when MEG reacts further with ethylene oxide, so it carries two ether linkages and a higher molecular weight (~106 g/mol). Compared with MEG it has a higher boiling point, lower volatility and a softer humectant profile. This is why DEG dominates resin, plasticizer and humectant applications, while MEG leads in antifreeze and PET production.
Why is triethylene glycol (TEG) the standard choice for natural gas dehydration?
TEG combines strong hygroscopicity with a high boiling point (around 285 °C), so it strips water efficiently from the gas stream and is easily re-concentrated in the regeneration column. Its low vapor pressure keeps carry-over losses minimal during processing. Together these properties have made TEG the industry standard for natural gas dehydration units.
Are DEG and TEG toxic, and how should they be handled safely?
DEG is toxic if ingested and must never be used in food, pharmaceutical or oral products; in industrial use, avoid skin and eye contact and wear personal protective equipment. TEG has comparatively lower acute toxicity but is still an industrial chemical and should be handled accordingly. Always read the current MSDS/COA and follow storage and handling rules for both products.
How can international buyers request a DEG or TEG quote from Turkey?
Pricing tracks the ethylene oxide and MEG market, purity grade, packaging (IBC, drum, bulk) and delivery terms, so it is quoted per order rather than listed online. As a supplier in Bursa, Turkey, we prepare current availability, technical documents and export pricing on request, including Incoterms and shipping documentation. Contact us with product, quantity and packaging details to receive a tailored quote.