Quick Answer
No. Mono-ethylene glycol (MEG, CAS 107-21-1) is not a hydrocarbon. It is classified as a dihydric alcohol (diol) - an oxygenated organic compound containing two hydroxyl (–OH) groups, which fundamentally distinguishes it from hydrocarbons that contain only carbon and hydrogen.
What Is Mono-Ethylene Glycol (MEG)?
Mono-ethylene glycol is a colorless, odorless, hygroscopic liquid with the chemical formula C₂H₆O₂. Learn more in our complete guide to what mono-ethylene glycol is.
Why MEG Is Not a Hydrocarbon?
Mono-ethylene glycol contains two oxygen atoms in the form of hydroxyl (-OH) groups. In contrast, true hydrocarbons such as ethane (C₂H₆) or propane (C₃H₈) contain only carbon and hydrogen atoms. This oxygen content fundamentally changes MEG's chemical behavior, making it highly polar and capable of strong hydrogen bonding, unlike nonpolar hydrocarbons.
MEG vs. Hydrocarbons - Key Property Comparison
| Property | Mono-Ethylene Glycol (MEG) | Typical Hydrocarbon (e.g., Hexane) |
|---|---|---|
| Chemical Class | Dihydric alcohol (diol) | Hydrocarbon |
| Formula | C₂H₆O₂ | C₆H₁₄ |
| Polarity | Highly polar | Nonpolar |
| Dielectric Constant (20°C) | ~37 | <2 |
| Boiling Point | ~197.3°C | ~69°C |
| Water Miscibility | Fully miscible | Immiscible |
| Primary Use | Oxygenated solvent, chemical intermediate | Fuel, petrochemical feedstock |
Why This Difference Matters - Polarity and Solubility
From a structural standpoint, hydrocarbons typically exhibit low polarity with dielectric constants below 2, whereas MEG has a dielectric constant of approximately 37 at 20°C, indicating strong polarity. This difference explains why MEG's polarity and water solubility make it fully miscible with water, while most hydrocarbons such as hexane remain immiscible due to their nonpolar molecular structure.
Boiling Point and Volatility
In terms of physical properties of MEG, MEG has a boiling point of about 197.3°C, significantly higher than typical hydrocarbons of similar molecular weight, such as hexane (~69°C). This elevated boiling point results from intermolecular hydrogen bonding, which is absent in hydrocarbon molecules and leads to much lower volatility and evaporation rates.
Industrial Classification and Applications
From an industrial classification perspective, hydrocarbons are primarily used as fuels and petrochemical feedstocks, while MEG is categorized as an oxygenated solvent and chemical intermediate. Global MEG production exceeds 25 million tons per year, mainly for polyester (PET) manufacturing and antifreeze applications - clearly distinguishing it from energy-focused hydrocarbon streams.
Related questions
Is ethylene glycol organic or inorganic?
MEG is an organic compound - it contains a carbon-based molecular structure with hydroxyl functional groups, classified specifically as a diol rather than a hydrocarbon.
Is MEG polar or nonpolar?
MEG is highly polar due to its two hydroxyl groups, which enable hydrogen bonding - the opposite of nonpolar hydrocarbons like hexane or octane.
What type of alcohol is mono-ethylene glycol?
MEG is classified as a dihydric alcohol (diol), meaning it contains two hydroxyl (–OH) groups per molecule, distinguishing it from monohydric alcohols like ethanol.
Is MEG a petrochemical?
While MEG is derived from petrochemical feedstocks (typically ethylene), the finished product itself is an oxygenated chemical intermediate, not a hydrocarbon fuel or feedstock.
Key takeaways
Summary
- MEG is a dihydric alcohol (diol) with two hydroxyl (–OH) groups, not a hydrocarbon
- Chemical formula C₂H₆O₂ - contains oxygen, unlike true hydrocarbons
- Highly polar (dielectric constant ~37 at 20°C) versus nonpolar hydrocarbons
- Boiling point ~197.3°C due to hydrogen bonding, much higher than similar hydrocarbons
- Used as an oxygenated solvent and chemical intermediate (PET, antifreeze), not as fuel
