Organophosphorus compounds for dental polymerizable compositions

A dental polymerizable composition comprising:

• (a) an organic phosphate compound having at least one radically polymerizable double bond, at least one phosphate residue having one or two hydroxyl groups, and at least one hydrocarbon group having 4 or more carbon atoms in a molecule, wherein a 10% by weight methanol solution of the organic phosphate compound has an electric conductivity at 25° C. of 0.5 mS/cm or less, and/or the organic phosphate compound has a light transmittance at 455 nm of 90% or more;
• and
• (b) a polymerizable monomer capable of copolymerizing with the organic phosphate compound.

A process for preparing a (meth)acrylic acid monoester monophosphate ester, comprising:

• reacting 1 to 5 moles of a diol having 4 to 30 carbon atoms with 1 mole of a (meth)acrylic acid at a reaction ratio of the (meth)acrylic acid of 60 to 90% by mol, to give a reaction mixture comprising a (meth)acrylic acid monoester of the diol and a (meth)acrylic acid diester of the diol, the molar ratio of the (meth)acrylic acid monoester of the diol to the (meth)acrylic acid diester of the diol being 2 to 8;
• and
• reacting the resulting (meth)acrylic acid monoester of the diol with a phosphorus oxychloride, to give the (meth)acrylic acid monoester monophosphate ester.

A process for preparing an organic phosphate compound, comprising subjecting a (meth)acrylate compound having at least one hydroxyl group as a raw material to phosphate esterification of hydroxyl group of the raw material with a phosphorus oxyhalide, wherein the (meth)acrylate compound is prepared by (meth)acrylic acid esterification of a polyol compound having an organic group having 4 or more carbon atoms and two or more hydroxyl groups in a molecule with a (meth)acrylic acid derivative while keeping at least one hydroxyl group, and wherein a content of a carbonyl compound in the polyol compound is 0.1% by mol or less.