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; Ar is a C 6 -C 16 aromatic group; which comprising:

(a) reacting o-phenylphenol with phosphorus trichloride in the presence of zinc chloride catalyst to form a 6-chloro-6H-dibenz [c,e] [1,2]oxaphosphorin of the following formula (II);

(b′) oxidizing the compound of formula (II) in the presence of water and ozone to form a 6-chloro-6-oxide-dibenz [c,e] [1,2]oxaphosphorin of the following formula (V);

 and

(c′) reacting a polyhydroxybenzene compound of the following formula (III)

(HO) n —Ar  (III)

 wherein, n and Ar are defined the same as the above, with the compound of formula (V) 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 1:2 to 1:3.

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

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

6. The method according to claim 1 , wherein the reaction step of (c′) is under a temperature of between 60° C. to 150° C.