Abstract: A process for producing a halogen-containing phosphate ester includes the steps of: (i) reacting a phosphorus halide selected from the group consisting of phosphorus oxyhalides and phosphorus pentahalides with a halogen-containing hydroxy compound to obtain a reaction mixture including a halogen-containing phosphate ester, (ii) purifying the halogen-containing phosphate ester by adding an aqueous medium selected from the group consisting of water, neutral aqueous solutions, acidic aqueous solutions and basic aqueous solutions to the reaction mixture to crystallize the halogen-containing phosphate ester, and (iii) distilling waste water from the purification step.

Abstract: A process for preparing an ester compound comprising reacting a halogen-substituted aliphatic hydroxy compound or aromatic hydroxy compound with a phosphorus oxyhalide or phosphorus pentahalide in the presence of 0.005 to 10 mol % of a phosphorus trihalide with respect to the hydroxy compound to obtain a phosphoric ester compound. Phosphoric ester compounds of high purity containing less coloring components can be prepared without using an antioxidant.