Ethanol → Cyclopropanecarboxylic acid, 3-(2,2-dichloroethenyl)-2,2-dimethyl-, ethyl ester

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The procedure described in Example 2 is repeated up to the point at which the mixture of 1-cyano-3-(2',2'-dichlorovinyl)-2,2-dimethylcyclopropane, sulphuric acid and water has been heated and stirred at 80° C. for 6 hours and then cooled below 30° C. 16 Parts of ethanol are added to the reaction mixture below 50° C. The mixture is then heated at 100° C. for a further 12 hours, cooled to 20° C. and drowned into 100 parts of water. The aqueous mixture is extracted with toluene (2×50 parts), the toluene extracts are combined and the solvent is removed by evaporation under reduced pressure. There are obtained 17.6 parts of ethyl 3-(2',2'-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylate as a brown oil containing 40.4% of the cis-isomer and 21.8% of the trans-isomer. The overall yield is 92.4%.

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