[CH3:1][O-:2].[Na+].[C:4](=O)([O:7][CH3:8])[O:5][CH3:6].[F:10][C:11]([F:15])=[C:12]([F:14])[F:13].S([O:21][CH3:22])(OC)(=O)=O>O1CCCC1>[CH3:1][O:2][C:12]([F:14])([F:13])[C:11]([F:15])([F:10])[C:4]([O:5][CH3:6])([O:7][CH3:8])[C:12]([F:14])([F:13])[C:11]([F:15])([F:10])[O:21][CH3:22]
A mixture of 27.0 g (0.50 mol) of sodium methoxide, 56.0 g (0.62 mol) of dimethyl carbonate, and 100 ml of dry tetrahydrofuran was agitated in a 350 ml tube under 1-3 atm of tetrafluoroethylene. Tetrafluoroethylene was pressured in as consumed until 110 g (1.1 mol) had been added. The mildly exothermic reaction kept the temperature near 35° C.; after the addition, the reaction mixture was heated at 40° C. for 1 hour. The viscous solution from this reaction was treated directly with 75.6 g (0.60 mol) of dimethyl sulfate at 40° C. for 15 hours. Filtration and distillation afforded 87.6 g (52%) of 1,3,3,5-tetramethoxyoctafluoropentane, bp 54° C. (0.3 mm Hg), nD24 1.3605, whose structure was confirmed by Ir 3.29, 3.33, and 3.42 (satd CH), 8-9μ (CF, COC). Nmr (CCl4) 'H δ 3.68 (s, 1, CF2OCH3) and 3.57 (p, JHF 1.3 Hz, 1, C (OCH3)2); 19F -88.2 (m, 1, CR2O) and -116.5 ppm (m, 1, CF 2).
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