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Insecticidal cyclopropane carboxylates prepn. - 3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropane-carboxylates from 1,1-dichloro-4-methyl-1,3-pentadiene and diazoacetates
Insecticidal cyclopropane carboxylates prepn. - 3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropane-carboxylates from 1,1-dichloro-4-methyl-1,3-pentadiene and diazoacetates
3-(2,2,-Dichlorovinyl)-2,2-dimethylcyclopropane-carboxylate esters (I) are prepd. by (a) reacting a water-soluble acid-addn. salt of a glycine ester with an alkali metal nitrite in an aq. medium in a first reactor, the aq. medium being in interfacial contact with a solvent which has a lower b.pt. than 1,1-dichloro-4-methyl-1,3-pentadiene (II), is immiscible with the aq. medium, and preferentially dissolves the resulting diazoacetate ester (III), (b) continuously transferring a stream of the (III) contg. solvent to a second reactor contg. an excess of (II) as well as a catalyst for promoting the release of N2 from the initial product of the reaction between (II) and (III), the second reactor being kept at a temp. high enough for the solvent to distill off; and (c) withdrawing the resulting mixt. of (I) and (II) from the second reactor and distilling off the (II). Cpds. (I) are useful as insecticides or intermediates therefor. The total amt. of (III) in the system at any given time is very small, so that explosion hazards are reduced.
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