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

Temperature

100 °C

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.

1. customThe zinc salt which has precipitated
2. filtrationis filtered off
3. extractionThe dark brown aqueous phase, extracted with pentane
4. extractionthe product is extracted with ethyl acetate
5. dry with materialAfter the organic phase has been dried over MgSO4
6. customevaporated in a rotary evaporator (RE), the residue
7. distillationis distilled in vacuo

ORD record

ord-3b5bd5bdad2344b08f05f11c901ccccb

Source dataset

uspto-grants-1990_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04892962