Abdellatif Manseri

Synthesis of telechelic dienes from fluorinated α,ω-diiodoalkanes. Part I. Divinyl and diallyl derivatives from model I(C2F4)nI compounds

Abstract The synthesis of five fluorinated non-conjugated dienes from commercially available α,ω-diiodoperfluoroalkanes is described. Preparation of the fluorinated divinyl derivatives H2C=CH(CF2)nCH=CH2 (n = 2, 4, 6) (2,2, 2,4 and 2,6) was effected by ethylenation of these diiodinated compounds in various ways followed by dehydroiodination in ethanolic potassium hydroxide. Allyl diolefines, H2C=CHCH2(CF2)nCH2CH=CH2 (4,4 and 4,6) were produced by the α,ω-bis-telomerization of allyl acetate followed by deiodoacetoxylation in the presence of zinc. The diacetate precursors 3,4 and 3,6 of the respective diallyls 4,4 and 4,6 were obtained rather than diacetate 3,2 because of the eventual decomposition of α,ω-diiodoperfluoroethane by β-scission. These five fluorinated non-conjugated dienes have been characterized by 1H, 13C and 19F NMR spectroscopy.

Synthesis of fluorinated telomers. Part 4. Telomerization of vinylidene fluoride with commercially available α,ω-diiodoperfluoroalkanes

Abstract The synthesis of a new fluorinated αω-diiodo telomer I[(TFE)(VDF),]I (A), where TFE and VDF represent tetrafluoroethylene and vinylidene fluoride respectively, has been carried out by telomerization of VDF with αω-diiodoperfluoroalkanes. The thermal telomerization of VDF with 1,2-diiodoperfluoroethane IC2 F4I led to good yields of the monoadduct IC2F4CH2CF2I and of the diadduct which was composed of an almost equimolar ratio of ICF2CH2C2F4CH2CF2I and IC2F4(CH2CF2)2I, together with a small amount of IC2F4CH2CF2CF2CH2I and a triadduct containing I (VDF) C2F4(VDF)2I and IC2F4(VDF)3. This procedure has been applied successfully to αω-diiodo-n-perfluorobutane and α,ω-diiodo-n-perfluorohexane. The reactivity of VDF relative to the fluorinated α,ω-diiodo telogens has been studied from which it is shown that the environment of the terminal group of the telogen is a major factor affecting the reactivity.

Synthèse de diènes téléchéliques à partir d' α,ω-diiodo-alcanes fluorés Partie II: Divinyls et diallyls présentant des motifs constitutifs tétrafluoroéthylène, fluorure de vinylidène et hexafluoropropène

Abstract Synthesis of new fluorinated non-conjugated dienes containing tetrafluoroethylene, vinylidene fluoride (VDF) and/or hexafluoropropene from α,ω -diiodofluorinated cotelomers was carried out by two methods in two steps. Divinyl monomers were obtained by α,ω -bis ethylenation of these cotelomers followed by a bis-dehydroiodination in medium yields which were lower when the cotelomers contained the VDF base unit. Diallylic olefins were produced by addition of these α,ω -diiodofluoroalkanes to allyl acetate followed by a ‘deiodoacetatization’ in high yields. Each telechelic diene was carefully characterized by 1 H and 19 F NMR.

UNEXPECTED TELOMERIZATION OF HEXAFLUOROPROPENE WITH DISSYMETRICAL HALOGENATED TELECHELIC TELOGENS

Abstract The synthesis of new fluorinated α,ω-diiodo telomers I(TFE) x (VDF) y (HFP) z I (A) where TFE, VDF and HFP represent tetrafluoro-ethylene, vinylidene fluoride and hexafluoropropene, respectively, was carried out by thermal telomerization of HFP with VDF oligomers, I(TFE) x (VDF) y I, as transfer agents. Compound A was obtained in 55% yield when x = y = 1, whereas almost no reaction occurred when x = 1 and y = 2. Interestingly, HFP reacted with IC 2 F 4 CH 2 CF 2 · selectively and not with ICF 2 CH 2 CF 2 CF 2 · whereas, from IC 4 F 8 CH 2 CF 2 I, HFP could be introduced on both end-groups but produced a higher amount of I(TFE) 2 (VDF)(HFP) I. The reactivity of HFP is compared with that of VDF in reactions with fluorinated α,ω -diiodinated telogens and it is shown that the environment of the terminal C-I bond in the telogen influences the orientation of the reaction.

Synthesis of fluorinated telomers. Part 6. Telomerization of hexafluoropropene with α,ω-diiodoperfluoroalkanes

Abstract The synthesis of highly fluorinated telomers produced from the thermal bulk telomerization of hexafluoropropene (HFP) with α,ω-diiodoperfluoroalkanes is described. That involving 1,2-diiodotetrafluoroethane was unsuccessful because of the thermal decomposition of this diiodide from 190°C. An optimization of the telomerization reaction involving 1,4-diiodoperfluorobutane taking into account key parameters such as the initial [IC 4 F 8 I] 0 /[HFP] 0 molar ratio, the temperature and the time of the reaction is attempted. The conditions for the highest conversion of IC 4 F 8 I and also for directing the reaction toward the monoadduct or the diadduct are discussed. Both these telomers were reduced with tributylstannane into HC 4 F 8 (C 3 F 6 ) x H (with x =1 or 2) and H–C 3 F 6 –C 4 F 8 –C 3 F 6 –H, the 1 H and 19 F-NMR spectra of which confirmed the structure of each derivative.

Radical addition of iodine monochloride to vinylidene fluoride

Abstract The radical addition of iodine monochloride to 1,1-difluoroethylene or vinylidene fluoride (VDF) leading to a ClCF 2 CH 2 I ( I )/ClCH 2 CF 2 I ( II ) mixture is described. Four different ways of initiation (thermal, photochemical, presence of radical initiators or redox catalysts) were used and all of them led to a high amount (≥98%) of isomer ( I ). The percentages of ( I ) and ( II ) isomers were determined by 19 F NMR and they were also deduced from those of ClCF 2 CH 3 and ClCH 2 CF 2 H obtained by selective reduction of the iodine atom of the product mixture, by tributylstannane. The reactivity of ICl to VDF and the high proportion of isomer ( I ) were interpreted by means of a thermodynamical approach from the enthalpy of formation of ( I ) and ( II ), respectively, determined by semi-empirical computations. In addition, heats of formation of both isomers and interactions between the SOMO of radicals and the HOMO of the fluoroolefin show that the mechanism of such a reaction occurs via the addition of I to the less fluorinated side of VDF.

Poly(vinylidene fluoride) Containing Phosphonic Acid as Anticorrosion Coating for Steel

Vinylidene fluoride (VDF)-based copolymers bearing pendant phosphonic acid function for potential application as anticorrosion coatings were synthesized via free radical copolymerization of VDF with a new phosphorus containing 2-trifluoromethacrylate monomer, (dimethoxyphosphoryl)methyl 2-(trifluoromethyl)acrylate (MAF-DMP). MAF-DMP was prepared from 2-trifluoromethacrylic acid in 60% overall yield. Radical copolymerizations of VDF with MAF-DMP initiated by tert-amyl peroxy-2-ethylhexanoate at varying ([VDF]0/[MAF-DMP]0) feed ratios led to several poly(VDF-co-MAF-DMP) copolymers having different molar percentages of VDF (79-96%) and number-average molecular weights (Mns) up to ca. 10 000 g mol-1 in fair yields (47-53%). Determination of the composition and microstructure of all the synthesized copolymers was done by 1H and 19F NMR spectroscopies. The monomer reactivity ratios of this new VDF/MAF-DMP pair were also determined (rVDF = 0.76 ± 0.34 and rMAF-DMP = 0 at 74 °C). The resulting poly(VDF-co-MAF-DMP) copolymers exhibited high melting temperature (162-171 °C, with respect to the VDF content), and the degree of crystallinity reached up to 51%. Finally, the pendant dimethyl phosphonate ester groups of the synthesized poly(VDF-co-MAF-DMP) copolymer were quantitatively hydrolyzed, giving rise to novel phosphonic acid-functionalized PVDF (PVDF-PA). In comparison to hydrophobic poly(VDF-co-MAF-DMP) copolymers (the water contact angle, WCA, was 98°), the hydrophilic character of the PVDF-PA was found to be surprisingly rather pronounced, exhibiting low WCA (15°). Finally, steel plates coated with PVDF-PA displayed satisfactory anticorrosion properties under simulated seawater environment.

Use of Original Fluorinated Telomers in the Synthesis of Hybrid Silicones

The wide use of fluorosilicones is the result of their combination of excellent properties: good resistance to heat, solvents, acids, alkalies, and oxidizing media. Gaskets for connectics, hydraulic fluids, and heat-carrier fluids still account for the largest number of applications. After a first generation proposed by Dow-Corning, fluorinated hybrid silicones based on well-architectured fluorooligomers built by controlled stepwise telomerization of various fluoroolefins are presented. Such cotelomers are very interesting precursors of functional or telechelic derivatives (containing hydroxy, carboxy, amine or unsaturated groups).