Patent ID: 7232921

Claim:
A method for preparing a biphenylphosphonate compound of the following formula (I): wherein n is 2 or 3; and Ar is a C 6 –C 16 aromatic group; comprising: (a) reacting o-phenylphenol with phosphorus trichloride in the presence of zinc chloride catalyst to form 6-chloro-6H-dibenz [c,e][1,2] oxaphosphorin of the following formula (II); (b) reacting a polyhydroxybenzene compound of the formula (III) (HO) n —Ar (III) wherein n and Ar are defined the same as the above, with the compound of formula (II) to form a compound of the following formula (IV) wherein n and Ar are defined the same as the above; and (c) oxidizing the compound of formula (IV) in the presence of water and ozone to form the compound of formula (I).