Free radical and isomerisation processes during the electrochemical fluorination of n-butyryl chloride, i-butyryl chloride and pivaloyl chloride in anhydrous hydrogen fluoride

Effect of alkyl chain length on the electrochemical perfluorination of n-alkane (C6–C10) carboxylic acid chlorides

“…Interestingly in all these cases perfluoro n-alkane carboxyl acids are in substantially large excess (9 to 11 times) when compare to perfluoro-iso-alkane carboxylic acids (Table 4). This observation confirms the earlier trend reported for perfluoro-n-butyric acid [30].…”

“…Recently it was shown that electrochemical perfluorination of n-butyric acid leads to the formation of a significantly higher quantity of perfluoro-n-butyric acid (PFNBA) 92% compared to perfluoro-iso-butyric acid (PFIBA) 6.9% [30], which also supports the present observation on the ECPF of alkane carboxylic acid chlorides (Scheme 3).…”

“…We have extended this study to n-butyryl, iso-butyryl and pivaloyl chlorides and explained the cause for higher conversion from iso-alkane carboxylic acid to n-alkane carboxylic acid during electrochemical fluorination [30]. The present work is an extension of this investigation based on the 19 F NMR data of the products formed during the ECPF of higher chain length n-alkane carboxylic acid chlorides.…”

“…Both perfluoro-n-alkanes and perfluoro-iso-alkanes are obtained (compound [21][22][23][24][25][26][27][28][29][30][31][32][33]. For all the five acid chlorides, the perfluoro-n-alkane content was found to be in the range 38-44%.…”

Products formed at intermediate stages of electrochemical perfluorination of propionyl and n-butyryl chlorides. Further evidence in support of NiF3 mediated free radical pathway

“…The HF soluble partially fluorinated intermediates were isolated at different stages of ECPF [3,6,7]. Many studies by Dimitrov et al [5][6][7][8], Sartori et al [9][10][11], and Velayutham et al [12] also confirmed the free radical pathway. Since anodically activated nickel is the only electrode in ECPF process, the involvement of high valent nickel fluoride species such as NiF 3 and NiF 4 in ECPF process has been suggested by Ignat'ev et al [9,11,13].…”