421-79-4Relevant articles and documents
Synthesis and polymerisation of fluorinated monomers bearing a reactive lateral group. Part 5 - Radical addition of iodine monobromide to chlorotrifluoroethylene to form a useful intermediate in the synthesis of 4,5,5-trifluoro-4-ene-pentanol
Ameduri,Boutevin,Kostov,Petrova
, p. 117 - 127 (2007/10/03)
The synthesis of the new halogenated alcohol BrCF2CFClCH2CHICH2OH as a precursor of 4,5,5 trifluoro-4-ene pentanol F2C=CFC3H6OH is based on a two-step process. First, the radical addition of iodine monobromide to chlorotrifluoroethylene (CTFE) led to the expected BrCF2CFClI (I) and ICF2CFClBr (II), but also to BrCF2CFClBr (III) and ICF2CFClI (IV), the amount of which determined by 19F NMR depended on the reaction conditions: by feeding CTFE into IBr continuously or in batches; photochemical or thermal initiations, and with various initial [IBr]0/[CTFE]0 molar ratios. In most cases, isomer (I) was mainly produced. The second step concerned the addition of such a mixture to allyl alcohol yielding the polyhalogenoalcohol with a quantitative conversion of (I). The reactivity of different halogeno end-groups of these isomers toward the allyl alcohol was discussed. Reduction of the iodine atom into hydrogen and the halogenated alcohol was accompanied by that of the bromine atom leading to BrCF2CFClC3H6OH and HCF2CFClC3H6OH (V). Dehalogenation of the former alcohol in the presence of zinc led to F2C=CFC3H6OH while dehydrochlorination of (V) into trifluorovinyl hydroxy monomers was achieved in the presence of potassium hydroxide but in poor yields. Strategies starting from the radical additions of iodine monochloride and of iodine monobromide were compared showing that the former led to better overall yields of trifluorovinyl alcohol than the latter.
