A novel approach to soluble polystyrenes functionalized by tri-n-butyltin carboxylates

The methyl esters (5a and 5b) of two omega-(para styryl)alkanoic acids, 3-p-styryl propionic and 5-p-styryl pentanoic acid, were respectively synthesized from 3-phenyl propionic acid and 5-phenyl pentanoic acid in four reaction steps. These esters have been submitted to radical copolymerization with styrene affording the corresponding copolymers. The methyl ester functions were subsequently converted into the tri-n-butyltin carboxylates using bis(tributyltin) oxide. This approach by-passes complications of radical polymerization inhibition due to the presence of tin in the monomers. It also avoids undesired, uncontrolled early stage polymerization of styryl moieties during the hydrolysis of the methyl esters into the corresponding carboxylic acid precursors of the monomeric tin carboxylates. Finally, it reduces significantly the polymerization time. Characterizations of the tin functionalized polymers in solution and solid state by NMR, IR and thermal techniques allow us to conclude that the tin atoms are tetracoordinated.