Decomposition Products from Pentafluorophenylmagnesium Bromide

On the attempted synthesis of salts with the trimethyl[bis(pentafluorophenyl)]silicate ion, [Me3Si(C6F5)2]−—A polyphenyl problem

“…In DMF and dimethylacetamide solution lowintensity signals were detected after prolonged 19 F NMR experiments (up to 16 h, 25,000 scans) at ambient temperature which were assigned to 1-H(C 6 F 4 ) n F (n = 2-4) in agreement with literature data [11]. Evidence for only four signal groups (À139 ppm (low intensity), À141, À154, À163 ppm (low intensity)) excludes directly the formation of polymers such as, e.g.…”

“…These results clearly demonstrate that fluoride-induced reactions of Me 3 SiC 6 F 5 exhibit a comparable reactivity as pentafluorophenyl Grignard reagents, Mg(C 6 F 5 )X, or pentafluorophenyl lithium, LiC 6 F 5 [11,13] -also showing comparable side-reactions -and may therefore be added to the group of highly reactive pentafluorophenyl element compounds suitable for nucleophilic substitutions.…”

Silver compounds in synthetic chemistry

“…The reaction principle has been extended to the acid chloride of pyridine 2,6-dicarboxylic acid 1k (Scheme 2). The sequential C 6 F 5 group transfer was monitored by 19 F NMR spectroscopy which showed only one characteristic set of multiplets after all AgC 6 F 5 had reacted to yield 2,6-bis(2 0 ,3 0 ,4 0 ,5 0 ,6 0 -pentafluorobenzoyl)pyridine 2k.…”

“…19 F NMR, d (ppm): À140.6 (m, 2F, F-2 0 ,6 0 ), À150.5 (tt, 1F, F-4 0 ), À160.6 (m, 2F, F-3 0 ,5 0 ), 13 C { 1 H} NMR, d (ppm): 171.6 (s, C O), 151.9 (s, C-2), 121.7 (s, C-3), 113.3 (s, C-4), 148.9 (s, C-5); 112.7 (broad, C-1 0 ), 137.5 (dm, C-2 0 ,6 0 ), 143.9 (dm, C-3 0 ,5 0 ), 142.6 (dm, C-4 0 ). The sample was contaminated by up to 10% of furan-2carboxylic acid.…”

“…In the case of reactions with Me 3 SiCF 3 , acid chlorides, anhydrides or activated esters can be used to prepare the corresponding bis(trifluoromethyl)carbinols via the intermediately formed trifluoromethyl ketone [17]. Reactions of LiC 6 F 5 [18], Mg(C 6 F 5 )X [19] or Me 3 SiC 6 F 5 (in the presence of fluoride) [20] with themselves give product mixtures of 1H-perfluorinated polyphenyls, C 6 F 5 (C 6 F 4 ) n H.…”