Synthesis of fluoro-substituted acrylic monomers bearing a functionalized lateral chain Part 1.Preparation of sulfur-containing monomers

摘要

The synthesis of sulfur-containing fluoroacrylic monomers C_mF2_(m+l)(CH_2)_2S(CH_2)nOC(O)CH=CH_2 (where m = 6, 8 and n = 2-4, 11) is presented from a two-step procedure. The first deals with the radical addition of fluorinated mercaptans CmF2m+l(CHV2SH onto ffi- unsaturated alcohols leading to new ffi-perfluorinated alcohols containing various polymethylene spacers CmF2m+l(CHV2S(CHVnOH according to the nature of the unsaturated alcohols. By-products were noted, resulting from the ~-addition of the thiyl radical onto the more hindered side of the alcohol. The proportion of linear and branched isomers is discussed according to the stability of the radical intennediates. These minor products were obtained selectively from other routes to confinn their presence in the reaction media. The second step deals with the acrylation reaction that occurred either in the presence of acryloyl chloride or from a Fisher esterification. Both reactions are described and discussed taking into account the nature of the starting alcohols. The fonnation of thiiranium ions as intennediates in the esterification of ~-sulfur-containing alcohols in acidic medium is established and the formation of regioisomers described according to this thiiraniurn moieties interposition.