What Is Ethylene Glycol Dibutyl Ether?
Ethylene glycol dibutyl ether is a compound with two ether groups.
It is also known by various other names, such as “ethylene glycol di-n-butyl ether,” “1,2-dibutoxyethane,” and “5,8-dioxadodecane.”
At room temperature, it is a colorless, to slightly pale-yellow liquid that is insoluble in water. It is flammable and should be kept away from heat, hot bodies, and fire.
Uses of Ethylene Glycol Dibutyl Ethers
Ethylene glycol dibutyl ether is used in the composition of a material called “photoresist.” Photoresist is a material used in semiconductor etching (a surface processing technique that uses the corrosive action of chemicals).
In the processing of semiconductor components, etching is used to form minute grooves for printing circuits and other components. What is important in etching is that only the areas to be etched are exposed to the chemical, while the areas not to be etched are coated with a corrosion-resistant photoresist.
In order to control the shape of the coated area precisely, a photoresist is applied to the semiconductor surface and then irradiated with light or electron beams of specific wavelengths to bake a pattern of the shape to be coated. After that, a developing solution is used to dissolve and remove the unneeded photoresist, and the areas without photoresist are etched.
This process selectively corrodes portions of semiconductors, making it possible to create integrated circuits with complex structures.
Characteristics of Ethylene Glycol Dibutyl Ether
Ethylene glycol dibutyl ether is represented by the molecular formula C10H22O2 . The structure is an ether bond of one molecule of ethylene glycol (C2H6O2), a divalent alcohol, and two molecules of butanol (C4H10O).
The basic properties (molecular weight, specific gravity, and solubility) of ethylene glycol dibutyl ether are as follows:
- Molecular weight: 174.28
- Specific Gravity: 0.725 (as a liquid at 0°C)
- Solubility: Insoluble in water
Other Information on Ethylene Glycol Dibutyl Ether
1. Ether of Divalent Alcohol
Ethylene glycol is a divalent alcohol with two hydroxy groups in its molecule. Each of these hydroxy groups forms an ether bond, so that dehydration condensation with two molecules of butanol yields ethylene glycol dibutyl ether.
Because oxygen atoms are highly electronegative, the ether bond is polarized. However, the ethylene glycol dibutyl ether molecule has a point-symmetric linear structure, so the molecule as a whole has low polarity.
2. Flammability
Ethylene glycol dibutyl ether is a flammable liquid. Since its flash point is 85°C, flammable vapor may be generated when used in exothermic reactions or in heating experiments.
Vapor density is higher than that of air, and if leaked indoors, it may be retained on the floor, so it is preferable to handle it in a draft with ventilation. In case of fire, use powder extinguisher, foam extinguisher, or carbon dioxide extinguisher. Since they are insoluble in water, bar pouring may cause the spread of fire and is very dangerous.
3. Explosive Oxides
Ethers can form explosive oxides (peroxides) when oxidized by contact with oxygen or exposure to ultraviolet light. Accumulation of explosive oxides may cause an explosion upon heating or impact.
To prevent the accumulation of oxides, it is effective to add antioxidants (hydroquinone, etc.), seal with nitrogen, or shield from ultraviolet rays. When using ethylene glycol dibutyl ether that has been stored for a long time, it is safer to check for the accumulation of oxides with a test paper.
4. Irritation and Toxicity
Ethylene glycol dibutyl ether is irritating to the skin and eyes. When handling, protective equipment such as protective gloves and safety glasses should be worn, and drafts or local exhaust ventilation should be operated to avoid exposure to vapors. If it adheres to the skin, it must be washed immediately.
Acute toxicity is also present, and the half lethal dose (LD50 value) in rats is 2,650 mg/kg administered orally. The substance name must be clearly indicated on the label, and the product must be stored and used in a well-ventilated area.