Toluene → alpha-Cypermethrin 1-Epimeric Mixture

Participants

Reaction Conditions

Reaction Steps

Cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (199 g, 0.95 M) was added to a solution of potassium carbonate (65.6 g, 0.475 M) in water (450 ml). Toluene (900 ml), tetra-n-butylammonium bromide (13.5 g, 0.05 M) and alpha-cyano-3-phenoxybenzyl p-toluenesulphonate (341 g, 0.9 M; prepared as described in A above) were added to the stirred mixture which was then heated at 70° C. for 3 hours. The mixture was cooled to ambient temperature and the organic phase was separated off, washed with aqueous potassium carbonate solution (2×200 ml) and water (2×200 ml), evaporated and degassed under vacuum to leave cis-alpha-cyano-3-phenoxybenzyl 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate as a pale amber oil (364 g, 97.3%), containing less than 1% trans-isomers.

Provenance & Evidence