Method for preparing a biphenylphosphonate compound

1. 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).

2. The method according to claim 1 , wherein the Ar is selected from the group consisting of:

3. The method according to claim 1 , wherein the molar ratio of o-benzylphenol to phosphorous trichloride in step (a) is between 1:1 to 1:2.

4. The method according to claim 1 , wherein the molar ratio of the compound of formula (III) to the compound of formula (II) in step (b) is between 1:2 to 1:3.

5. The method according to claim 1 , wherein the molar ratio of water to the compound of formula (II) in step (c) is between 1:20 to 1:5.

6. The method according to claim 1 , wherein the reaction in step (a) is under a temperature between 30° C. to 200° C.

7. The method according to claim 1 , wherein the reaction in step (b) is under a temperature between 60° C. to 150° C.