Fluorosulfuric acid → Difluoromalonyl fluoride

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Reaction Steps

A mixture of 624 g (4.0 mol) of methyl difluorofluoroformylacetate, 348 g (3.5 mol) of fluorosulfonic acid and 25 ml of HSbF6 (0.3 mol) was charged to a 1 liter Teflon® pot fitted with a Teflon® condenser connected to a trap cooled to -80°. The mixture was stirred and heated at 80° to 110° for about 24 h. Then, 187 g (65% yield) of crude difluoromalonyl fluoride was collected which, after trap-to-trap distillation, was analyzed by NMR at -30°. NMR (CCl4): 19F 21.0 (t, JFF 10.9 Hz, 2F, COF) and -112.4 ppm (t, JFF 10.9 Hz, 2F, CF2) with a very small amount of impurity showing at -162.1 ppm. Distillation of a 140 g sample gave 118 g of pure FCOCF2COF, b.p. -4° to -5°. Dimethyl difluoromalonate was also formed.

Provenance & Evidence