Ethyl a-chloroethyl ether

A. ot-Chloroelhyl ethyl ether. A mixture of 200 g. (201 ml.) of redistilled paraldehyde, b.p. 121-122.5° (equivalent to 4.54 moles of acetaldehyde), and 200 g. (254 ml., 4.34 moles) of absolute ethanol is placed in a 1-1. three-necked flask fitted with a mechanical stirrer and a gas inlet tube reaching to the bottom of the flask. The mixture is cooled to —5° in a mixture of Dry Ice and acetone, and dry hydrogen chloride (Note 1) is passed into the stirred reaction mixture maintained at about —5° until 200 g. (5.48 moles) has been absorbed. During this operation, which requires about 2 hours, the reaction mixture separates into two layers. The upper layer of crude a-chloroethyl ethyl ether is re-... 

Chloroethyl benzoate, 30,11 a-Chloroethyl ethyl ether, 36, 60 Chlorohydroquinone, 35, 27 -Chloromandelic acid, 35,14 Chloromethylation, 30, 68 2-Chloro-2-methylcyclohexanone, 37, 8... 

Ion-Formation from a-Chloroethyl Ethyl Ether and Antimony Pentachloride, P.H. Plesch and V.T. Stannett, Journal of Macromolecular Science Chemistry, 1982, A18, 425-430. 

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). 

On the other hand, if diethyl ether is treated at —20° or below with one equivalent of chlorine, a-chloroethyl ethyl ether is formed in 42% yield. Further chlorination at this low temperature leads to a,a -di-chlorodiethyl ether in 57% yield, the second chlorine atom entering a new alpha position in preference to an alpha position already substituted. The extension of this new technique to higher ethers is under way. Other methods are available for the preparation of a- and /3-halo ethers (see Chapter 6). 

Dry hydrogen chloride (100 g., 2.75 moles) is passed into a mixture of 100 g. (0.76 mole) of paraldehyde and 100 g. (2.18 moles) of ethyl alcohol cooled in an ice bath. Hood.) The upper layer formed during the hydrogen chloride addition is separated and dried over calcium chloride. Distillation gives 162 g. (69%) of a-chloroethyl ethyl ether boiling at 93-96°. 

Preparation (b). The reaction sequence is shown in the formulation. Treatment of paraldehyde and absolute ethanol with hydrogen chloride gas at —5° produces a-chloroethyl ethyl ether (1), which on bromination affords a,j8-dibromoethyl ethyl ether (2). Coupling with allylmagnesium bromide gives (3), which on reaction with zinc dust in n-butanol generates 1,4-pentadiene. Thus one double bond is that of allyl bromide, and the other is generated by elimination of BrOCjH, from the bromohydrin ethyl ether (3). 

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