Competitive study of the reactions Br + RFI → IBr + RF and determination of bond dissociation energies D(RF−I) where RF = CF3, C2F5, n-;C3F7, i-C3F7, and n-C4F9

✍ Scribed by Ernest N. Okafo; Eric Whittle

• Publisher: John Wiley and Sons
• Year: 1975
• Tongue: English
• Weight: 526 KB
• Volume: 7
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550070210

✦ Synopsis

The overall photobromination reactions Brz + RFI -+ IBr + RFBr have been studied using a competitive technique. obtained for the rate-determining step (16) Relative Arrhenius parameters were Br + RFI -+ IBr + R F These were placed on an absolute basis using previous absolute values of A and E for The activation energies were used to calculate bond dissociation energies RFI = CFJ. D(R-I) with the following results: R FI Ev, D(RFI) (kcal/mole)

~ ~ ____ ~~ ~ ~~ CFJa 10.8 52.6 C2Fd 8.8 50.6 n-C 3F71 7.4 49.2 i-CsF71 7.5 49.2 n-CaFpI 6.7 48.4 El6 from [I].

The D ( R r 1 ) are compared with related D(R-I) and it is concluded that for a given alkyl group R H and the corresponding perfluoroalkyl group RF, D ( R r 1 ) > D ( R r 1 ) whereas it has previously been found that D ( R g X ) < D ( R r X ) where X is not iodine.