Jérôme Alric

The importance of the nature of initiator and solvent in atom transfer radical polymerization of methyl methacrylate catalyzed by copper(I) N-alkyl-2-pyridylmethanimine complexes

The effect of the nature of initiator and solvent in atom transfer radical polymerization of methyl methacrylate (MMA) using N-pentyl-2-pyridylmethanimine as the ligand in the presence of Cu(I)Br has been investigated. Under identical concentration and temperature conditions, p-toluenesulfonyl chloride (p-TsCl) in diphenyl ether gives polymerization rates identical to ethyl 2-bromoisobutyrate in xylene. However, the former system induces better control of molecular weights and lower polydispersities.

Synthesis of fluorinated telomers. Part 6. Telomerisation of chlorotrifluoroethylene with methanol

Bulk radical telomerisation of chlorotrifluoroethylene (CTFE) with methanol was investigated for the synthesis of fluorinated alcohols. Improvements in the conversion of CTFE and of the selectivity of the reaction were sought by using different radical initiators (peroxides, percarbonates, peresters) and an excess of methanol. These reactions were compared in terms of CTFE conversion, yield of monoadduct and formation of higher molecular weight telomers. Under these conditions, radical initiated telomerisations systematically led to low molecular weight CTFE telomers. 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane (DHBP) proved to be the most effective radical initiator. All these experiments revealed the low chain transfer activity of methanol in the presence of CTFE. A thorough structural study of typical CTFE–methanol telomers was performed by 19F, 1H and 13C NMR spectroscopies. These analytical methods allowed us to prove the highly regioselective formation of HOCH2CF2CFClH (produced with a 95% selectivity), showing the regioselectivity of the addition of hydroxymethyl radicals onto the difluoromethylene side of CTFE.