Ethylene oxide chlorohydrin process

Ethylene oxide (qv) was once produced by the chlorohydrin process, but this process was slowly abandoned starting in 1937 when Union Carbide Corp. developed and commercialized the silver-catalyzed air oxidation of ethylene process patented in 1931 (67). Union Carbide Corp. is stiU. the world s largest ethylene oxide producer, but most other manufacturers Hcense either the Shell or Scientific Design process. Shell has the dominant patent position in ethylene oxide catalysts, which is the result of the development of highly effective methods of silver deposition on alumina (29), and the discovery of the importance of estabUshing precise parts per million levels of the higher alkaU metal elements on the catalyst surface (68). The most recent patents describe the addition of trace amounts of rhenium and various Group (VI) elements (69). 

Dehydrochlorination to Epoxides. The most useful chemical reaction of chlorohydrins is dehydrochlotination to form epoxides (oxkanes). This reaction was first described by Wurtz in 1859 (12) in which ethylene chlorohydria and propylene chlorohydria were treated with aqueous potassium hydroxide [1310-58-3] to form ethylene oxide and propylene oxide, respectively. For many years both of these epoxides were produced industrially by the dehydrochlotination reaction. In the past 40 years, the ethylene oxide process based on chlorohydria has been replaced by the dkect oxidation of ethylene over silver catalysts. However, such epoxides as propylene oxide (qv) and epichl orohydrin are stiU manufactured by processes that involve chlorohydria intermediates. 

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. 

The chlorohydrin process (24) has been used for the preparation of acetyl-P-alkylcholine chloride (25). The preparation of salts may be carried out mote economically by the neutralization of choline produced by the chlorohydrin synthesis. A modification produces choline carbonate as an intermediate that is converted to the desired salt (26). The most practical production procedure is that in which 300 parts of a 20% solution of trimethyl amine is neutralized with 100 parts of concentrated hydrochloric acid, and the solution is treated for 3 h with 50 parts of ethylene oxide under pressure at 60°C (27). 

Ethylene oxide [75-21-8] was first prepared in 1859 by Wurt2 from 2-chloroethanol (ethylene chlorohydrin) and aqueous potassium hydroxide (1). He later attempted to produce ethylene oxide by direct oxidation but did not succeed (2). Many other researchers were also unsuccesshil (3—6). In 1931, Lefort achieved direct oxidation of ethylene to ethylene oxide using a silver catalyst (7,8). Although early manufacture of ethylene oxide was accompHshed by the chlorohydrin process, the direct oxidation process has been used almost exclusively since 1940. Today about 9.6 x 10 t of ethylene oxide are produced each year worldwide. The primary use for ethylene oxide is in the manufacture of derivatives such as ethylene glycol, surfactants, and ethanolamines. 

Ethylene oxide has been produced commercially by two basic routes the ethylene chlorohydrin and direct oxidation processes. The chlorohydrin process was first iatroduced dufing World War I ia Germany by Badische Anilin-und Soda-Eabfik (BASE) and others (95). The process iavolves the reaction of ethylene with hypochlorous acid followed by dehydrochlofination of the resulting chlorohydrin with lime to produce ethylene oxide and calcium chloride. Union Carbide Corp. was the first to commercialize this process ia the United States ia 1925. The chlorohydrin process is not economically competitive, and was quickly replaced by the direct oxidation process as the dominant technology. At the present time, all the ethylene oxide production ia the world is achieved by the direct oxidation process. 

Chlorohydrin Process. Ethylene oxide is produced from ethylene chlorohydrin by dehydrochlorination using either sodium or calcium hydroxide (160). The by-products include calcium chloride, dichloroethane, bis(2-chloroethyl) ether, and acetaldehyde. Although the chlorohydrin process appears simpler, its capital costs are higher, largely due to material of constmction considerations (197). 

Merck and Maeder have patented the manufacture of arecaidine by loss of water from l-methyl-4-hydroxypiperidine-3-carboxylic acid. A method of producing the latter has been describd by Mannich and Veit and has been developed by Ugriumov for the production of arecaidine and arecoline. With the same objective, Dankova, Sidorova and Preobrachenski use what is substantially McElvain s process,but start by converting ethylene oxide, via the chlorohydrin and the cyanohydrin, into -chloropropionic acid. The ethyl ester of this with methylamine in benzene at 140° furnishes methylbis(2-carbethoxyethyl) amine (I) which on refluxing with sodium or sodium Moamyloxide in xylene yields l-methyl-3-carbethoxy-4-piperidone (II). The latter is reduced by sodium amalgam in dilute hydrochloric acid at 0° to l-methyl-3-carbethoxy-4-hydroxypiperidine (III) which on dehydration, and hydrolysis, yields arecaidine (IV R = H), convertible by methylation into arecoline (IV R = CH3). 

The Teijin oxychlorination, on the other hand, is considered a modern version of the obsolete chlorohydrin process for the production of ethylene oxide. In this process, ethylene chlorohydrin is obtained by the catalytic reaction of ethylene with hydrochloric acid in presence of thallium(III) chloride catalyst ... 

The classical chlorohydrin route has an atom efficiency of 25% and is better described as a calcium chloride process, with ethylene oxide as the major by-product. In other words, even if... 

Lefort A process for making ethylene oxide by oxidizing ethylene in the presence of a silver catalyst. Invented and developed in the 1930s by T. E. Lefort at the Societe Frangaisc de Catalyse. For maty years, refinements of this basic process were operated in competition with the ethylene chlorohydrin process, but by 1980 it was the sole process in use. 

You have to talk about propylene oxide and propylene glycol after ethylene oxide and glycol. Its not that the chemical configurations are so similar (they are), or that the process chemistry is about the same (it is). The Fact is that much of the propylene oxide is now made in plants originally designed and constructed to produce EO, not PO. As you read in the last chapter, the chlorohydrin route to EO was abandoned by the 1970s in favor of direct oxidation. At the same time, the EO producers found that the old EO plants were suitable for the production of PO and certainly the cheapest hardware available to satisfy growing PO demands. 

Another example of a famous organic chemical reaction being replaced by a catalytic process is furnished by the manufacture of ethylene oxide. For many years it was made by chlorohydrin formation followed by dehydrochlorination to the epoxide. Although the chlorohydrin route is still used to convert propylene to propylene oxide, a more efficient air epoxidation of ethylene is used and the chlorohydrin process for ethylene oxide manufacture has not been used since 1972. 

Ethylene oxide was formerly made in a two-stage process by first adding HOCl to ethylene and then removing HCl. However, in the 1960s Scientific Design, Union Carbide, and Shell Oil developed a one-step direct oxidation process that has largely replaced the old chlorohydrin process. 

The direct oxidation of ethylene to EO by O2 has now replaced the chlorohydrin process entirely because it is cheaper and involves less byproducts, but propylene oxide (a monomer in polyurethanes) is still made by the chlorohydrin route. 

Propylene oxide is produced from the chlorohydrination of propene similar to the process used to make ethylene oxide (see Ethene). A major use of propylene oxide involves hydrating propylene oxide to produces propylene glycol, propylene polyglycols, and other polyether polyols. These products are used to produce both rigid and flexible polyurethane foams, but they are also used to produce polyurethane elastomers, sealants, and adhesives. 

Ethylene and Propylene Oxides. Ethylene oxide (26) and its derivatives are among the important aliphatic chemicals the 1950 production amounted to between 400,000,000 and 500,000,000 pounds. The chlorohydrin process was introduced in the early 1920 s and the direct oxidation process in the 1930 s, both based on ethylene. In the older process, the one most used today, the ethylene reacts in solution with hypo-chlorous acid at room temperature. 

To exemplify the second relationship, process competition, there are the two alternate routes from ethylene to ethylene oxide-direct oxidation and chlorohydrination. Even more involved is the acetic acid picture, in which, as has been described, at least ten processes have been in use at the same time in commercial competition with one another. 

Ethylene Chlorohydrin. Two industrial processes were used in the synthesis of ethylene chlorohydrin,182 191 which, in turn, was transformed to ethylene oxide. Since the direct oxidation of ethylene to ethylene oxide is more economical, these technologies are being abandoned. 

Epoxides are important intermediates in many industrial processes. For example, the reaction of the simplest epoxide, ethylene oxide, with water is employed to produce ethylene glycol, which is used in antifreeze and to prepare polymers such as Dacron. One method for the preparation of ethylene oxide employs an intramolecular nucleophilic substitution reaction of ethylene chlorohydrin ... 

Ethylene oxide was discovered in 1859 by Wurtz. He stated that ethylene oxide could not be made by direct oxidation of ethylene, and it was nearly 80 years before this was disproved. Wurtz made ethylene oxide by the method known today as the chlorohydrin process, in which ethylene is reacted in turn with hypochlorous acid and base. This process was commercialized during World War I in Germany, and until 1985 was still used commercially in the United States. 

Early production was based on the chlorohydrin process (Box 2), characterized by high yields but also encumbered by technical and environmental problems due to the use of chlorine. The introduction, in the 1940-1950s, of the oxidation of ethylene on silver catalysts with lower costs and better environmental standards, led to its phasing out, virtually completed by the end of the 1960s. 

The industrial production of ethylene and propylene oxides was historically dependent on the chlorohydrin process, a multistep procedure that proceeds via the stoichiometric reaction of propylene (or ethylene) with chlorine and water to yield a mixture of chlorohydrin isomers (only one for ethylene) and hydrochloric acid. The epoxide is formed upon reaction of the chlorohydrins with calcium or sodium hydroxide. All the chlorine used in the process eventually ends up as chlorinated organic and inorganic by-products (Equation B2). 

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