What Is Triethylene Glycol?
Triethylene glycol (TEG), an organic compound with the molecular formula C6H14O4, is a divalent alcohol formed by the condensation of three glycol molecules. It has a molecular weight of 150.174, a melting point of -7°C, a boiling point of 285°C, and a density of 1.1255 g/mL. TEG is a clear, colorless, viscous liquid at room temperature with a weak sweet odor, soluble in water and ethanol but insoluble in ether. Classified as a Class 4 Hazardous Flammable Liquid, it has a high flash point of 177°C but is flammable and requires careful handling.
Uses of Triethylene Glycol
TEG is used in various applications, including as an air humidity regulator, gas absorbent, solvent, brake fluid, cellophane softener, raw material for synthetic organics, plasticizer for vinyl polymers, and in natural gas pipelines. It is notable for its use in dehydrating gases in natural gas pipelines due to its low evaporation loss. TEG is also an additive for photoresist release solutions in semiconductor manufacturing, enhancing the effectiveness of the solution.
1. Natural Gas Pipelines:
TEG dehydrates CO2 and H2S gases more effectively than ethylene glycol (MEG) and diethylene glycol (DEG).
2. Additives for Photoresist Release Solution:
TEG is used in the semiconductor industry to pattern micro-level electrode structures on substrates using photoresists.
3. Other Applications:
It is also used as a thickener in cosmetics, a fragrance ingredient, an active ingredient in air disinfectants, and as a solvent due to its high flash point and non-toxicity.
Principle of Triethylene Glycol
TEG shares properties with mono- and diethylene glycols, such as increased boiling point and viscosity with more glycol units. It is synthesized by reacting ethylene oxide with water in the presence of an acid catalyst, yielding a mixture of mono-, di-, tri-, and tetra-ethylene glycols.
Types of Triethylene Glycol
TEG is available both as a reagent for research and as an industrial chemical. It is sold in various volumes, from 500 mL reagent bottles to large 1000 L containers. Stable at room temperature, it is widely used in humidity control and as a solvent for cellulose and resins.