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

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A solution of 24.2 parts of m-phenoxybenzyl acetate, 28.4 parts of ethyl 2,2-dimethyl-3-(2'-,2'-dichlorovinyl)-cyclopropanecarboxylate (cis:trans ratio, 58/42) and 1.3 parts of tetraethyl titanate in 200 parts of dry toluene was stirred and heated at the boiling point. The azeotrope of ethyl acetate and toluene was removed by distillation at the rate of 50 parts per hour while maintaining the reaction volume by the addition of fresh toluene. After 4 hours 5 parts of water were added and precipitated titanium dioxide removed by filtration. The toluene was then removed by heating under reduced pressure and 0.3 mm. of mercury. Volatile fractions removed were 9.0 parts of unreacted ethyl 2,2-dimethyl-3-(2',2'-dichlorovinyl)cyclopropanecarboxylate, boiling at 75°-80° and 6.3 parts of unchanged m-phenoxybenzyl acetate, boiling at 125°-135°. There was obtained 26.85 parts of m-phenoxybenzyl 2,2-dimethyl-3-(2',2'-dichlorovinyl)-cyclopropanecarboxylate (cis trans ratio, 44/56).

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