Acetaldehyde chlorohydrin

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). 

In this work on compounds containing the C—F link, it was obviously desirable to prepare 2-fluoroethanol, both for toxicity tests on the compound itself, and as a starting material for the production of other fluorine compounds. Swarts1 was unable to obtain 2-fluoroethanol by the action of silver fluoride or mercuric fluoride on either ethylene chlorohydrin or ethylene bromohydrin. He obtained acetaldehyde in each case. He ultimately obtained fluoroethanol in very poor yield by the indirect method of hydrolysing fluoroacetin (from bromoacetin and mercuric fluoride) for 80 hr. with dilute mineral acid. 

Chemical/Physical. Chlorination of 2-chloroethyl vinyl ether to a-chloroethyl ethyl ether or P-chloroethyl ethyl ether may occur in water treatment facilities. The alpha compound is very unstable in water and decomposes almost as fast as it is formed (Summers, 1955). Although stable in NaOH solutions, in dilute acid solutions hydrolysis yields acetaldehyde and chlorohydrin (Windholz et al., 1983). At pH 7 and 25 °C, the hydrolysis half-life is 175 d (Jones and Wood, 1964). 

Chloroethanol is also formed from ethylene in the presence of pyridine and necessarily cupric chloride even with low chloride ion concentration [55], whereas in the absence of CUCI2 acetaldehyde is the sole product. With chiral amines and phosphines as ligands instead of pyridine, optically active chlorohydrins can be obtained from higher a-oleftns [56, 57]. 

Use Manufacture of polyethylene, polypropylene, ethylene oxide, ethylene dichloride, ethylene glycols, aluminum alkyls, vinyl chloride, vinyl acetate, ethyl chloride, ethylene chlorohydrin, acetaldehyde, ethyl alcohol, polystyrene, styrene, polyvinyl chloride, SBR, polyester resins, trichloroethylene, etc. as a refrigerant, in welding and cutting of metals, an anesthetic, and in orchard sprays to accelerate fruit ripening. 

Liquid, djj 1.0525. bp7w 109°, Quite stable to NaOH solns. Even dil acids produce hydrolysis to acetaldehyde and ethylene chlorohydrin [2-chloroet hanof). LDjq orally in rats 250 mg/kg, Smyth et al.. J. Ind. Hyg. Toxicol. 31, 60 (1949). 

EXPLOSION and FIRE CONCERNS noncombustible solid, but contact with water may release heat sufficient to ignite combustible materials NFPA rating Health 3, Flammability 0, Reactivity 1 can ignite or react violently with acetic acid, acetaldehyde, acetic anhydride, acrolein, acrylonitrile, allyl chloride, aluminum, chlorine trifluoride, chloroform and methanol, chlorohydrin, chlorosulfonic acid, 1,2-dichloroethylene, glyoxal, hydrogen chloride, hydrogen fluoride, hydroquinone, nitric acid, sulfuric acid, nitroethane, nitropropane, nitromethane, tetra-hydrofuran, water, zinc, and others reacts to form explosive products with ammonia and silver... 

It hydrolyzes with dilute acids to form acetaldehyde and ethylene chlorohydrin. Reactions with concentrated acids can become violent. 

Somfai s group demonstrated the use of a Lil-promoted vinylaziridine-3-pyrroline rearrangement in the formal synthesis of the antibiotic (-)-anisontycia The commercially available 2-(4-methoxyphenyl)acetaldehyde 43 was subjected to Brown allylation followed by aminolysis of the resulting chlorohydrin to afford the enantioenriched aminoalcohol 44 f Scheme 11.34). The enantiopure cis-vinylaziridine 45 was then prepared by O- and N-tosylation of the chiral aminoalcohol followed by KOH-promoted ring closure. Microwave-assisted rearrangement of vinylaziridine 45 using Lil as an additive afforded enantioenriched 3-pyrroline 46 in excellent yield, and this was converted to the natural product in several steps tScheme 11.34T ... 

However, a series of papers by Henry have established that Cl and CuClj do not trap the same intermediate that leads to the formation of acetaldehyde. In the presence of high concentrations of chloride, the hydroxyalkyl intermediate contains chloride instead of hydroxide within the coordination sphere of the metal, and the hydroxyalkyl intermediate is stabilized toward p-hydrogen elimination. The fonnation of ethylene chlorohydrin is favored at high [CT] because its rate law is inverse first order in Cl (Equation 16.101), whereas oxidation to form aldehyde is inverse second order in Ch... 

An alternate process, rarely used for commercial production, involves the reaction of ethylene with hypochlorous acid to form ethylene chlorohydrin. This chlorohydrin is then dehydrochlorinated with lime to produce ethylene oxide and calcium chloride. Major by-products of this process are 1,2-dichloroethane, bis-(2-chloroethyl) ether, acetaldehyde, trace acetylenes, and other chlorinated hydrocarbons. The reaction product is purified by fractional distillation. 

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