Iodine → 2,2-Difluoro-4-pentenoic acid

Participants

Reaction Conditions

Reaction Steps

100.0 g (0.59 mol) of allyl chlorodifluoroacetate, 42.2 g (0.65 mol) of zinc dust (activated according to Fieser & Fieser), 96.7 g (0.88 mol) of trimethylchlorosilane and 400 ml of absolute acetonitrile are introduced together into a glass autoclave, a spatula tip of iodine is added and the mixture is heated for 48 hours at 100° C. The zinc salt which has precipitated is filtered off, the filtrate is hydrolysed with H2O and rendered basic with 2N NaOH. The dark brown aqueous phase, extracted with pentane, is acidified with half-concentrated HCl, and the product is extracted with ethyl acetate. After the organic phase has been dried over MgSO4 and evaporated in a rotary evaporator (RE), the residue is distilled in vacuo. Yield: 59.4 g (74%) of a colourless oil of boiling point 73°-75° C./15.6 mbar.

Provenance & Evidence