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

The synthesis of sulfur-containing fluoroacrylic monomers CmF2m + 1(CH2)(2) S(CH2)(n)OC(O)CH=CH2 (where m = 6, 8 and n = 2-4, 11) is presented from a t wo-step procedure. The first deals with the radical addition of fluorinated mercaptans CmF2m +1(CH2)(2)SH onto omega- unsaturated alcohols leading to new omega -perfluorinated alcohols containing various polymethylene spacers CmF2m +1(CH2)(2)S(CH2)(n)OH according to the nature of the unsaturated alc ohols. By-products were noted, resulting from the beta -addition of the thi yl radical onto the more hindered side of the alcohol. The proportion of li near and branched isomers is discussed according to the stability of the ra dical intermediates. These minor products were obtained selectively from ot her routes to confirm 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 desc ribed and discussed taking into account the nature of the starting alcohols . The formation of thiiranium ions as intermediates in the esterification o f beta -sulfur-containing alcohols in acidic medium is established and the formation of regioisomers described according to this thiiranium moieties i nterposition. (C) 2001 Elsevier Science B.V. All rights reserved.