Chlorohydrins ethylene chlorohydrin

Ethylene chlorohydrin [107-07-3J, HOCH2CH2CI, is the simplest chlorohydrin. It may also be called 2-chloroethanol, 2-chloroethyl alcohol, or glycol chlorohydrin. Ethylene chlorohydrin is ahquid at 15°C and 101.3 kPa (1 atm) (Table 1). This polar compound is miscible with water [7732-18-5] and ethanol [64-17-5] and is slightly soluble in ethyl ether [60-29-7] (5). 

HOCHj CHjOH. Colourless, odourless, rather viscous hygroscopic liquid having a sweet taste, b.p. 197 C. Manufactured from ethylene chlorohydrin and NaHC03 solution, or by the hydration of ethylene oxide with dilute sulphuric acid or water under pressure at 195°C. Used in anti-freezes and coolants for engines (50 %) and in manufacture of polyester fibres (e.g. Terylene) and in the manufacture of various esters used as plasticizers. U.S. production 1979 1 900 000 tonnes. 

CH3 CH0H CH20H, a colourless, almost odourless liquid. It has a sweet taste, but is more acrid than ethylene glycol b.p. 187. Manufactured by heating propylene chlorohydrin with a solution of NaHCO under pressure. It closely resembles dihydroxyethane in its properties, but is less toxic. Forms mono-and di-esters and ethers. Used as an anti-freeze and in the preparation of perfumes and flavouring extracts, as a solvent and in... 

BrCHisCHjBr + 2NaOH —> HOCHjCHisOH + 2NaBr Industrially, it is produced directly from ethylene by the addition of hypo, chlorous acid, followed by treatment of the resulting ethylene chlorohydrin with sodium bicarbonate solution ... 

ClCHjCHjOH + NaHCOj —> HOCHjCHjOH + COj + NaCl When ethylene chlorohydrin is heated with sodium hydroxide solution, the highly reactive cyclic ether, ethylene oxide, is formed ... 

Methyl acrylate is usually prepared from ethylene chlorohydrin thus ... 

Chlorohydrin 61 is formed by the nucleophilic addition to ethylene with PdCl2 and CuCl2[103,104]. Regioselective chlorohydroxylation of the allylic amine 62 is possible by the participation of the heteroatom to give chlorohydrin 63. Allylic sulfides behave similarly[105]. 

In the early versions, ethylene cyanohydrin was obtained from ethylene chlorohydrin and sodium cyanide. In later versions, ethylene oxide (from the dkect catalytic oxidation of ethylene) reacted with hydrogen cyanide in the presence of a base catalyst to give ethylene cyanohydrin. This was hydrolyzed and converted to acryhc acid and by-product ammonium acid sulfate by treatment with about 85% sulfuric acid. 

Ethylene glycol was originally commercially produced in the United States from ethylene chlorohydrin [107-07-3J, which was manufactured from ethylene and hypochlorous acid (eq. 8) (see Chlorohydrins). Chlorohydrin can be converted direcdy to ethylene glycol by hydrolysis with a base, generally caustic or caustic/bicarbonate mix (eq. 9). An alternative production method is converting chlorohydrin to ethylene oxide (eq. 10) with subsequent hydrolysis (eq. 11). 

Some substituted alkyl hydrogen sulfates are readily prepared. Eor example, 2-chloroethyl hydrogen sulfate [36168-93-1] is obtained by treating ethylene chlorohydrin with sulfuhc acid or amidosulfuhc acid. Heating hydroxy sulfates of amino alcohols produces the corresponding sulfuhc monoester... 

Where X is Br or Q, the free acids may be obtained by acidification of the alkaline solution, but where X is I, the acids must be isolated as salts to avoid reduction of the arsonic acids by HI. Rather than using alkyl haUdes, alkyl or dialkyl sulfates or alkyl arenesulfonates can be used. Primary alkyl haUdes react rapidly and smoothly, secondary haUdes react only slowly, whereas tertiary haUdes do not give arsonic acids. AHyl haUdes undergo the Meyer reaction, but vinyl hahdes do not. Substituted alkyl haUdes can be used eg, ethylene chlorohydrin gives 2-hydroxyethylarsonic acid [65423-87-2], C2H2ASO4. Arsinic acids, R2AsO(OH), are also readily prepared by substituting an alkaU metal arsonite, RAs(OM)2, for sodium arsenite ... 

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). 

Benzyl chloride readily forms a Grignard compound by reaction with magnesium in ether with the concomitant formation of substantial coupling product, 1,2-diphenylethane [103-29-7]. Benzyl chloride is oxidized first to benzaldehyde [100-52-7] and then to benzoic acid. Nitric acid oxidizes directly to benzoic acid [65-85-0]. Reaction with ethylene oxide produces the benzyl chlorohydrin ether, CgH CH20CH2CH2Cl (18). Benzylphosphonic acid [10542-07-1] is formed from the reaction of benzyl chloride and triethyl phosphite followed by hydrolysis (19). 

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. 

Hydrolysis to Glycols. Ethylene chlorohydrin and propylene chlorohydrin may be hydrolyzed ia the presence of such bases as alkaU metal bicarbonates sodium hydroxide, and sodium carbonate (31—33). In water at 97°C, l-chloro-2-propanol forms acid, acetone, and propylene glycol [57-55-6] simultaneously the kinetics of production are first order ia each case, and the specific rate constants are nearly equal. The relative rates of solvolysis of... 

Formation of Cyclic Carbonates. In the absence of water, chlorohydrins such as 2-chloroethanol and l-chloro-2-propanol react with an alkah carbonate or bicarbonate to produce cycHc carbonates such as ethylene carbonate [96-49-1] and propylene carbonate [108-32-7] ia yields of up to 80%... 

Esterification. Chlorohydrins can react with salts of carboxyUc acids to form esters. For example, 2-hydroxyethyl benzoate [134-11-2] was prepared ia 92% yield by heating sodium benzoate [532-32-1] with an excess of ethylene chlorohydrin ia the presence of a small amount of diethylamine... 

Etherification. A mixture of ethylene chlorohydrin ia 30% aqueous NaOH may be added to phenol at 100—110°C to give 2-phenoxyethanol [122-99-6] ia 98% yield (39). A cationic starch ether is made by reaction of a chlorohydfin-quaternary ammonium compound such as... 

Oxidation. Monochloroacetic acid [79-11-8] may be synthesized by the reaction of ethylene chlorohydrin with nitric acid [7697-37-2]. Yields of greater than 90% are reported (41). >Beta-chlorolactic acid (3-chloro-2-hydroxypropanoic acid) [1713-85-5] is produced by the reaction of nitric acid with glycerol monochlorohydrin (42). Periodic acid [10450-60-9] and glycerol monochlorohydfin gives chloroacetaldehyde [107-20-0] ia 50% yield (43). 

QuaterniZation. Choline chloride [67-48-1] was prepared ia nearly quantitative yield by the reaction of trimethylamine [121-44-8] with ethylene chlorohydrin at 90—105°C and 981—1471 kPa (10—15 kg/cm ) pressure (44). Precursors to quaternary ammonium amphoteric surfactants have been made by reaction of ethylene chlorohydrin with tertiary amines containing a long chain fatty acid group (45). 

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. 

Ghlorohydrination with er -All l Hypohalites. Olefins react with ethyl hypochlorite [624-85-1] to form the corresponding chlorohydrin (49). In 1938 both Shell Development Co. (50) and Arthur D. Litde, Inc. (51) patented the preparation of chlorohydrins by the reactions of olefins with tertiary alkyl hypochlorites. Examples with ethylene and propylene in the Shell patent reported chlorohydrin yields of greater than 95% with tert-huty hypochlorite [507-40-4]. 

The merchant market for chi orohydrin s is small, primarily for specialty appHcations. Ethylene chlorohydrin is sold ia the United States by BASF Corp., Parsippany, N.J., available ia 230 kg net lined steel dmms. Glycerol monochlorohydrin (3-chloro-l,2-propanediol) is available from Dixie Chemical Co., Houston, Tex., in lined steel dmms (227.3 kg net) from Raschig Corp., Richmond, Va. and from Henley Chemicals, Inc., Montvale, N.J., ia steel dmms (240 kg net). Glycerol dichi orohydrin (l,3-dichloro-2-propanol) is not currentiy being produced for the U.S. merchant market but has been available ia the past at a selling price of 5—6/kg. 

Toxicity of 2-Ghloroethanol. Ethylene chlorohydrin is an irritant and is toxic to the Hver, kidneys, and central nervous system. In addition, it is rapidly absorbed through the skin (73). The vapor is not sufficiently irritating to the eyes and respiratory mucous membranes to prevent serious systemic poisoning. Contact of the Hquid in the eyes of rabbits causes moderately severe injury, but in humans corneal bums have been known to heal within 48 hours. Several human fataUties have resulted from inhalation, dermal contact, or ingestion. One fatahty was caused by exposure to an estimated 300 ppm in air for 2.25 hours. In another fatal case, autopsy revealed pulmonary edema and damage to the Hver, kidneys, and brain (73). 

Ethylene chlorohydrin may be used in the manufacture of dye intermediates, pharmaceuticals, plant-protection agents, pesticides, and plastici2ers (3). 

Ethylene Chlorohydrin Technical BuUetiu, BASF Corp., Parsippany, N.J., 1989. 

An earlier procedure for the production of choline and its salts from natural sources, such as the hydrolysis of lecithin (23), has no present-day apphcation. Choline is made from the reaction of trimethyl amine with ethylene oxide [75-21-8] or ethylene chlorohydrin [107-07-5J. 

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). 

Like the formation of a-cyanohydrins, this reaction is catalyzed by bases or cyanide ion, but unlike the a-cyanohydrin case this reaction is not reversible, and under certain conditions it can proceed with violence. Ethylene cyanohydrin can also be prepared by the reaction of ethylene chlorohydrin and alkaH cyanides (39). 

Manufacture of alkylsulfones, important intermediates for metal-complex dyes and for reactive dyes, also depends on O-alkylation. An arylsulphinic acid in an aqueous alkaline medium is treated with an alkylating agent, eg, alkyl haUde or sulfate, by a procedure similar to that used for phenols. In the special case of P-hydroxyethylsulfones (precursors to vinylsulfone reactive dyes) the alkylating agent is ethylene oxide or ethylene chlorohydrin. 

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