Ethylene chlorohydrin, displacement

For many years ethylene chlorohydrin was manufactured on a large iadustrial scale as a precursor to ethylene oxide, but this process has been almost completely displaced by the direct oxidation of ethylene to ethylene oxide over silver catalysts. However, siace other commercially important epoxides such as propylene oxide and epichlorohydrin cannot be made by direct oxidation of the parent olefin, chlorohydrin iatermediates are stiU important ia the manufacture of these products. 

Ethylene chlorohydrin vapors form an explosive mixture with air the LEE and UEL values are 4.9% and 15.9% by volume of air, respectively. Among the hazardous reaction products are ethylene oxide, formed by internal displacement of the chlorine atom by the alkoxide ion, ethylene glycol formed by hydrolysis with sodium bicarbonate at 105°C (221°F), and ethylene cyanohydrin resulting from the reaction with alkali metal cyanides. 

The most important example of this reaction is the formation of ethylene oxide (Eqn. 1), over Ag-catalysts which displaced the two-step chlorohydrine route (Eqn. 2). Ethylene oxide is used in the production of ethylene glycol, antifreeze, polyesters and surfactants, and accounts for 18% of U.S. ethylene consumption (Figure 3). ... 

Ethylene oxide was conventionally prepared by reacting CI2, ethylene, and water to produce chlorohydrin, which is further treated with caustic to generate the oxide. This process was superseded by the direct oxidation of ethylene in the presence of silver catalysts with air or oxygen. The isobutane process displaced the route fiom propylene chlorohydrin to produce PO. Another significant loss was the conversion of DuPont s hexamethylene diamine process from butadiene to a non-chlorine-based technology. All these changes led to a loss of 140 000 tons of market demand for chlorine. 

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