Antifreeze from ethylene oxide

Ethylene glycol (HOCH2CH2OH) is the major component of antifreeze. It is readily prepared from ethylene oxide by reactions discussed in Section 9.15. It is sweet tasting but toxic. 

Ethylene glycol, HOCH2CH2OH, is used as antifreeze. It is produced from ethylene oxide, C2H4O, by the reaction... 

Ethylene oxide, the simplest epoxide, is an intermediate in the manufacture of both ethylene glycol, used for automobile antifreeze, and polyester polymers. More than 4 million tons of ethylene oxide is produced each year in the United Slates by air oxidation of ethylene over a silver oxide catalyst at 300 "C. This process is not useful for other ejroxides, however, and is of little value in the laboratory. Note that the name cfhyletie oxide is not a systematic one because Ihe -cue ending implies the presence of a double bond in the molecule. The name is frequently used, however, because ethylene oxide is derived from ethylene by addition of an oxygen atom. Other simple epoxides are named similarly. The systematic name for ethylene oxide is 1,2-epoxyethanc. 

Epoxide rings are cleaved by treatment with acid just as other ethers are. The major difference is that epoxides react under much milder condition-because of ring strain. Dilute aqueous acid at room temperature is sufficiem to cause the hydrolysis of epoxides to 1,2-diols, also called vicina/glycols.(Th word vicinal means adjacent," and a glycol is a diol.) More than 3 millK tons of ethylene glycol, most of it used for automobile antifreeze, are produci each year in the United States by acid-catalyzed hydration of ethylene oxid Note that the name ethylene glycol refers to the glycol derived from ethylen just as ethylene oxide refers to the epoxide derived from ethylene. 

Ethylene glycol is commonly used as antifreeze in automobiles. The feedstock includes pure water and refined ethylene oxide. This system combines a blending feed tank, glycol reactor, and a series of distillation columns. Olefin manufacturing includes three major processes the first converts natural gas to ethylene, propylene, or butane the second produces isobutylene and isoamy-lene from hydrocarbon feedstocks the third converts gas oil feedstocks into high-octane gasoline, distillates, and C2-C5 olefins. Plastics manufacturing employs a number of polymer processes that handle polyethylene, polypropylene, and butyl polymers. 

Among the oxygenates, glycol is a very desirable product. Most of it is used as antifreeze but a considerable part of the production is also used as a solvent or an intermediate for further reactions. A direct synthesis from syngas should be competitive with the present pathways via ethylene and ethelene oxide. This seems easy, but the present homogeneous catalysts... 

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