What Is Ethylene Oxide?
Ethylene oxide is a two-carbon organic compound with a cyclic ether structure.
It is also known as epoxyethane, and oxirane. It is a gas at room temperature and is soluble in water and organic solvents.
Uses of Ethylene Oxide
Ethylene oxide is used either in its raw state or as a raw material for synthesizing other compounds.
In its raw state, ethylene oxide is used as powerful disinfectant. It is used in a disinfection process called ethylene oxide sterilization, and is effective in sterilizing items with low heat resistance that cannot withstand sterilization at high temperatures.
When used as a raw material for synthesis, it is often used as a raw material for polyethylene oxide, which is a polymerization of ethylene glycol and ethylene oxide. In addition, it is also used as a raw material for ethanolamine, ethylene carbonate, and alkyl ethers.
Because polyethylene oxide are highly hydrophilic, it can be combined with hydrophobic alkyl groups to form surfactants, which can be used as nonionic surfactants in detergents.
Characteristics of Ethylene Oxide
Ethylene oxide has the molecular formulaCH2CH2O, has the molecular weight of 44.05, and is a gaseous organic compound at room temperature and pressure, with a specific gravity of 0.8711 at 20°C. It has a flash point of -17.8°C, a boiling point of 10.7°C, and freezing point of -111.3°C. It is well soluble in water, acetone, ether, etc.
It has a cyclic ether structure, and ring-opening polymerization creates polyethylene oxide, a polyether. It generally reacts readily with active hydrogen compounds.
Other Information on Ethylene Oxide
1. Production Method of Ethylene Oxide
Ethylene oxide are synthesized by contact oxidation of ethylene with oxygen. Although air (mixed gas with nitrogen) can be substituted for oxygen, the oxygen method, which uses oxygen as the raw material, is currently the most common method.
A mixture of ethylene gas and oxygen (ethylene concentration 20~35%) is introduced into a multi-tube reaction column filled with a silver catalyst and reacted under conditions of 230~315℃ and pressure of 851~2,127kPa. Afterwards, ethylene oxide of high purity are obtained through several stages of washing and separation, followed by further distillation. The yield of this production method is about 80%.
Main reaction formula: C2H4 + 1/2O2 → C2H4O (ethylene oxide)
Sub-reaction: C2H4 + 3O2 → 2CO2 + 2H2O
The most common method is to oxidize ethylene with oxygen, but hydrolysis neutralization of ethylene chlorohydrin (C2H4ClOH) was also used. Although this method has high yield, it is no longer used because of its high cost and lower purity compared to the method of direct oxidation of ethylene.
2. Precautions for Ethylene Oxide
Handling
Ethylene oxide has fairly wide explosion range of 3.0~100%, and decomposition and explosion may occur even in the absence of oxygen. Not only is fire strictly prohibited, but it should be stored in a cool, well-ventilated, dark place out of direct sunlight.
Since its vapor density is heavier than air at 1.52, if it leaks, it will stay underfoot and the odor will likely go unnoticed. Strict control is essential because of the danger of explosion caused by the slightest addition of energy.
Toxicity
Ethylene oxide has been judged to be equivalent to “a substance known to be toxic to humans for reproduction” due to several reports of increased miscarriages from epidemiological studies, as well as clear effects such as germ cell mutagenicity from animal studies.
Other acute toxic effects include blistering if it adheres to the skin, keratitis may occur if it gets into the eyes, and inhalation of large amounts of the vapor may cause anesthetic effects and death. Protective eyewear, protective gloves, and gas masks for organic gases should be worn when handling this product.