Abstract: A method for producing an aromatic diphosphate comprising: Step 1 which is a step where a specific aromatic monohydroxy compound having a steric hindrance group at ortho-positions is made to react with phosphorus oxyhalide in the presence of a Lewis acid catalyst and then the unreacted phosphorus oxyhalide is removed under a reduced pressure to give a specific; and Step 2 which is a step where the reaction product obtained in the above step is made to react with a specific aromatic dihydroxy compound in an amount of 0.5 mol to 1 mol of halogen contained in the reaction product in the presence of a Lewis acid catalyst to give a specific aromatic diphosphate.

Abstract: A method for producing an aromatic diphosphate comprising: Step 1 which is a step where a specific aromatic monohydroxy compound having a steric hindrance group at ortho-positions is made to react with phosphorus oxyhalide in the presence of a Lewis acid catalyst and then the unreacted phosphorus oxyhalide is removed under a reduced pressure to give a specific; and Step 2 which is a step where the reaction product obtained in the above step is made to react with a specific aromatic dihydroxy compound in an amount of 0.5 mol to 1 mol of halogen contained in the reaction product in the presence of a Lewis acid catalyst to give a specific aromatic diphosphate.

Abstract: A method of purifying an organic phosphoric ester characterized by treating a crude organic phosphoric ester with an epoxy compound and treating the treated organic phosphoric ester with an alkaline aqueous solution to purify it. The purification method is effective in stably obtaining an organic phosphoric ester reduced in acid value and excellent in heat resistance, hydrolytic resistance, and storage stability, regardless of the kind or amount of the organic phosphoric ester, the treating conditions, etc.

Abstract: A process for preparing aromatic bisphosphates includes: a first step of reacting an aromatic monohydroxy compound having a steric hindrance group at the ortho position, with a phosphorus oxyhalide in the presence of a Lewis acid catalyst (a) to yield a reaction mixture containing diarylphosphorohalidate, and a second step of reacting the reaction mixture of the first step with an aromatic dihydroxy compound in the presence of a Lewis acid catalyst (b) to obtain an aromatic bisphosphate, wherein the aromatic monohydroxy compound and the phosphorus oxyhalide are reacted in a molar ratio of 2.0:1.0-1.1 in the first step, and the reaction mixture of the first step is subjected to a distillation treatment before the reaction of the second step, thereby obtaining the aromatic bisphosphate of high purity.

Abstract: A method of pulverizing aromatic phosphates which comprises stressing an oily product of an aromatic phosphate having a purity of 90% or more at a temperature lower by 5.degree. to 100.degree. C. than a melting point of the aromatic phosphate in a temperature-controllable kneader to solidify and pulverize the aromatic phosphate.According to the present invention, aromatic phosphates industrially obtained are able to be solidified and pulverized in a short time in a simple way without being subjected to specific purification. Further, the invention is industrially advantageous in that the solidification and pulverization can be performed successively after production of the aromatic phosphate.