O.[S:2]([O-:5])([O-:4])=[O:3].[K+:6].[K+].S(S([O-])=O)([O-])(=O)=O.[K+].[K+].[C:17]([F:26])([O:21][C:22]([F:25])([F:24])[F:23])=[C:18]([F:20])[F:19]>O>[F:19][C:18]([F:20])([S:2]([O-:5])(=[O:4])=[O:3])[CH:17]([F:26])[O:21][C:22]([F:25])([F:24])[F:23].[K+:6]A 1-gallon Hastelloy C276 reaction vessel is charged with a solution of 114 g potassium sulfite hydrate (KHSO3.H2O, 95%, Aldrich, 0.72 mol), 440 g potassium metabisulfite (K2S2O5, 99%, Mallinckrodt, 1.98 mol) and 2000 mL of deionized water. The pH of this solution is 5.8. The vessel is cooled to −35° C., evacuated to −3 psig (81 kPa), and purged with nitrogen. This evacuate/purge cycle is repeated two more times. 600 g perfluoro(methyl vinyl ether) (PMVE, 3.61 mol) is added to the vessel, which is heated to 125° C. at which time the internal pressure is 462 psig (3290 kPa). The reaction temperature is maintained at 125° C. for 6 hr. The pressure drops to 25 psig (275 kPa) at which point the vessel is vented and cooled to 25° C. Once cooled, a white crystalline precipitate of the forms, leaving clear colorless liquid above it (pH=7). 19F NMR of the white solid shows it to be the desired product in high purity (>98%). 19F NMR of the liquid shows a small but detectable amount of the hydration product of Equation (3), above.
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