Synthesis and polymerisation of fluorinated monomers bearing a reactive lateral group. Part 5 1 Part 4, see [18] 1 – Radical addition of iodine monobromide to chlorotrifluoroethylene to form a useful intermediate in the synthesis of 4,5,5-trifluoro-4-ene-pentanol (original) (raw)

1999, Journal of Fluorine Chemistry

The synthesis of the new halogenated alcohol BrCF 2 CFClCH 2 CHICH 2 OH as a precursor of 4,5,5 tri¯uoro-4-ene pentanol F 2 C=CFC 3 H 6 OH is based on a two-step process. First, the radical addition of iodine monobromide to chlorotri¯uoroethylene (CTFE) led to the expected BrCF 2 CFClI (I) and ICF 2 CFClBr (II), but also to BrCF 2 CFClBr (III) and ICF 2 CFClI (IV), the amount of which determined by 19 F 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 BrCF 2 CFClC 3 H 6 OH and HCF 2 CFClC 3 H 6 OH (V). Dehalogenation of the former alcohol in the presence of zinc led to F 2 C=CFC 3 H 6 OH while dehydrochlorination of (V) into tri¯uorovinyl 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 tri¯uorovinyl alcohol than the latter. # 0022-1139/99/$ ± see front matter # 1999 Elsevier Science S.A. All rights reserved. P I I : S 0 0 2 2 -1 1 3 9 ( 9 8 ) 0 0 2 8 0 -2 4.5.1. 4-Chloro-4,5,5-trifluoropentanol (IY b H ) 1 H NMR (CDCl 3 ) : 1.90(qi, 3 J HH 6.2 Hz, CH 2 CH 2 OH, 2H); 2.23(m, CFClCH 2 , 2H); 2.75 (broad singlet, shifted with dilution or in the presence of Cl 3 CNCO); 3.68 (t, shifted to 4.50 ppm in the presence of Cl 3 CNCO, 3 J HH 6.6 Hz, CH 2 OH, 2H); 5.81 (td, 2 J HF 54.8 Hz, 3 J HF 3.2 Hz, HCF 2 , 1H). F NMR (CDCl 3 ) : À125.33(tddd, X part of an ABX system, 3 J FcH 10.4 Hz, 3 J FcFa 10.7 Hz, 3 J FcFb 9.7 Hz, 3 J FcH 3.3 Hz, CF c Cl, 1F); À130.30 (AB part, Fa À129.35, 2 J FaFb 284.4 Hz, 3 J FaFc 10.6 Hz, 2 J FaH 55.0 Hz, Fb À131.28, 2 J FbFa 283.7 Hz, 3 J FbFc 9.9 Hz, 2 J FbH 55.0 Hz) 16.5 g (0.064 mol) of a second pure fraction was distilled (colourless liquid) Bp, 90±928C/21 mm Hg (yield49.6%). (dddt, 3 J HF 22.5 Hz, 4 J HF 2.4 Hz, 4 J HF 4.0 Hz, 3 J HH 6.8 Hz, CFCH 2 , 2H); 3.15 (broad singlet, shifted with dilution or with Cl 3 CNCO, OH, 1H); 3.66 (t, shifted to 4.40 ppm with Cl 3 CNCO, 3 J HH 6.3 Hz, CH 2 OH). F NMR (CDCl 3 ) : À106.1 (ddt, 2 J FFgem 88.4 Hz, 3 J FF 32.0 Hz, 4 J FH 2.5 Hz); À125.2(ddt, 2 J FF 88.4 Hz, 3 J FF 113.6 Hz, 4 J FH 3.9); À174.6(ddt, 3 J FF 32.0 Hz, 3 J FF 113.6 Hz, 3 J FH 22.5 Hz). 13 C NMR (CDCl 3 ) : 21.9(dd, 2 J CF 22.4 Hz, 3 J CF 2.2 Hz, CFCH 2 ); 28.2 (d, 3 J CF 2.3 Hz, CH 2 CH 2 OH); 61.2 (s, CH 2 OH); 128.5 (ddd, 1