Fluorine-19 NMR study on the conformation changes of 1,1,2,2-tetrafluoro-1,2-disilacyclohexanes

How Trimethyl(trifluoromethyl)silane Reacts with Itself in the Presence of Naked Fluoride—A One‐Pot Synthesis of Bis([15]crown‐5)cesium 1,1,1,3,5,5,5‐Heptafluoro‐2,4‐bis(trifluoromethyl)pentenide

“…Bis([15]crown-5)cesium 1,1,1,3,5,5,5-heptafluoro-2,4-bis(trifluoromethyl)pentenide: A quantity of CsF (0.30 g, 2 mmol) was added in one portion to a well-stirred mixture of Me 3 SiCF 3 (3.40 g, 24 mmol) and [15]crown-5 (0.88 g, 4 mmol) in anhydrous dimethoxyethane (4 mL) at À20 8C. The mixture was slowly warmed to ambient temperature (about 3 h) and vigorously stirred for another 12 h. All volatile materials were condensed in vacuo at room temperature; the residue was washed with anhydrous benzene (2 3 mL), dried in vacuo and dissolved in diethyl ether.…”

“…[10] www.chemeurj.org Together with the angle C33-C34-C35 of 134.4(2)8, these data appear to be representative for a (CF 3 ) 2 CCC(CF 3 ) 2 moiety in comparison with literature values. [13] The process of formation of the "allyl" anion-addition of a fluoride source to tetrakis(trifluoromethyl)allene [13][14][15] -appears to be reversible; [Cs( [15]crown-5) 2 ][(CF 3 ) 2 CCFC-(CF 3 ) 2 ] decomposes selectively at a temperature above 230 8C into 1,1,1,5,5,5-hexafluoro-2,4-bis(trifluoromethyl)penta-2,3-diene (1,1,3,3-tetrakis(trifluoromethyl)allene) [16] and cesium fluoride with release of two equivalents of the crown ether (Scheme 4).…”

“…Solid [Cs( [15]crown-5) 2 ]-[(CF 3 ) 2 CCFC(CF 3 ) 2 ] (3.52 g, 3.8 mmol) was heated to 230 8C under a weak flow of nitrogen for 2.5 h. Volatile products were collected in a cold trap at À78 8C. After distillation (CF 3 ) 2 C=C=C(CF 3 ) 2 was obtained (0.60 g, 51 % yield).…”