Preparation of fluoroolefins by reaction of polyfluorochlorocarbinols with phosphorus pentasulfide

Generation and reactions of halodifluoromethide ions

“…19 was treated with LiCl/HMPA alone in refluxingTHF. These results indicate that either substitution of the para fluorine by chloride decreases the reactivity of the carbonyl group of 21 toward nucleophilic attack relative to the carbonyl in 19, or the ortho fluorines of 19 and 21 deactivate the carbonyl carbon toward nucleophilic attack relative to 6a or both.Similar inhibition by ortho fluorines in nucleophilic attack at the a position has been reported previously 18. Other fluorinated products were detected in trace amounts in this reaction mixture by 19F NMR spectroscopy.…”

“…Authentic samples of 7a and 7b were prepared for comparison purposes in 28 and 46% yields, respectively, via the addition of phenyllithium and n-butyllithium to chloropentafluoroacetone, similar to related organolithium additions to this ketone reported by Dyatkin and co-workers. 18 The alcohols were the only fluorinated products observed. Similar decomposition of 3 in the presence of a-chloro-a,a-difluoroacetophenone (8) The major product of this reaction was the olefin 10 which was obtained in a 50% yield.…”

“…40 An 18% (1.00 g, 3.6 mmol) isolated yield of 9 was also obtained which was identical in all respects with an authentic sample prepared via the addition of phenylmagnesium bromide to difluorotetrachloroacetone. 18 Attempted Preparation of 11a. A solution of potassium hydroxide (2.0 g, 35 mmol) in water (15 mL) was added dropwise to 7a (5.21 g, 20 mmol) with vigorous stirring.…”

“…The residue was separated by preparative GLC on column D to give a 30% (2.12 g, 9 mmol) isolated yield of 24: mass spectrum, m/e (relative intensity) 237 (12), 235 (35), 216 (12), 200 (100), 150 (13), 105 (10), 100 extracts were combined and dried over anhydrous magnesium sulfate. The Skellysolve was evaporated, and the residue was separated by preparative GLC on column B to give a 15% (1.06 g, 3.0 mmol) yield of (Z)-l-chloro-3-(3-bromophenyl)hexafluoro-2-butene, which was characterized as follows: mass spectrum, m/e (relative intensity) 356 (18), 354 (61), 352 (47), 273 (11), 254 (11), 238 (99), 219 (12), 188 (22), 169 (100), 98 (12), 73 (11), 69 (15), 51 (11) (caled for C10H4BrClF6, 353.6 g/mol); 19F NMR (10% DCC13, CFC13 ext) * +55.3 ppm (d of q, 2 F, CF2C1), +60.6 ppm (d of t, 3 F, CF3), +109.8 ppm (q of t, 1 F, vinyl F), =/(ClCF2, CF3) = 1.3 Hz, «/(C1CF2, vinyl F) = 11. 4 Hz, =/(CF3, vinyl F) = 24.1 Hz. Also isolated was a mixture of (E)-l-chloro-3-(3-bromophenyl)hexafluoro-2-butene and 4-chloro-2-(3-bromophenyl)hexafluoro-1-butene (0.35 g, 1.0 mmol, 5%, and 0.35 g, 1.0 mmol, 5%, respectively) as determined by 19F NMR analysis of the mixture.…”