New Phosphonated Methacrylate Monomers with C2/C3 Spacers

Syntheses of new phosphonated methacrylates with 2 or 3 hydrocarbon methylene spacers were investigated in order to avoid the conventional methacrylation of hydroxyphosphonate compounds with methacryloyl chloride. The first possibility concerns the esterification of methacrylic anhydride in the presence of either 2-hydroxyethylphosphonate or 3-hydroxypropylphosphonate. This reaction was proved to be quantitative when a basic catalyst, i.e. n-methylimidazole, was used at 60°C. However, this reaction also generates a side product, i.e. methacrylic acid, which was difficult to remove due to it having similar solubility to both dimethyl(2-methacryloyloxyethyl)phosphonate and dimethyl(2-methacryloyloxypropyl)phosphonate. The second process was based on the alcoholysis of MMA in the presence of the above hydroxy compounds. This reaction also proceeded quantitatively with Zr(AcAc)4 as acid catalyst. Unlike esterification of methacrylic anhydride, this second process did not require any solvent. The final phosphonated methacrylates were obtained with high purity, as the side product of the reaction (i.e., methanol) could be easily removed due to the azeotropic behavior of MMA/Methanol.