Ethylene oxide (oxirane) [75-21-8], Mr 44.05, is the simplest cyclic ether. It is a colorless gas or liquid and has a sweet, etheric odor. The ethylene oxide molecule with its short C–C bond and strained angles is shown in Figure 1 [6]. Theoretical calculations of the structure are in good agreement with experimental results [7].
Ethylene oxide is very reactive because its highly strained ring can be opened easily, and is thus one of the most versatile chemical intermediates. Because of its reactivity and toxicity it is also a hazardous compound that has been involved in a number of serious incidents. A good understanding of its properties is a necessary prerequisite for its safe handling. Ethylene oxide was first described in 1859 by WURTZ [8], who prepared it by eliminating hydrochloric acid from ethylenechlorohydrin, using potassium hydroxide solution. Industrial production by the chlorohydrin process began in 1914 and was based on WURTZ’s discovery. Since then the production and importance of ethylene oxide have steadily grown.
In 1931, LEFORT [9] discovered the direct catalytic oxidation of ethylene [74-85-1], which gradually superseded the chlorohydrin process. Currently, ethylene oxide is produced by direct oxidation of ethylene with air or oxygen; annual worldwide production capacity is ca. 15 106 t, making it an important industrial chemical. Ethylene oxide itself is used as a disinfectant, sterilizing agent, and fumigant. Its most important derivative is ethylene glycol [107-21-1], which is used in antifreeze (car radiators) (! Antifreezes) and for the manufacture of polyester fibers (! Fibers, 5. Polyester Fibers; ! Polyesters). Other ethylene oxide derivatives, amines and poly(ethylene glycols), are used in surfactants, solvents, etc.
There is some endogenous formation from ethylene in humans [10], and it has been discovered in an interstellar source [11].
As atmospheric pollutant it is present in natural gas, cigarette smoke, and diesel exhaust. Though ethylene oxide in nature is rare its biological action may have a fundamental impact on DNA and RNA evolution of whole biological systems [12].
