Synthesizing and purifying method for high-purity bicyclophosphonate

The invention provides a synthesizing and purifying method for high-purity bicyclophosphonate, and relates to the synthesizing and purifying method for the high-purity bicyclophosphonate. The invention aims to solve the problem that a target product obtained by a current synthetic method of the cyclophosphonate has low purity and poor thermal stability, and after the target product is finished toform a fabric, the fabric has a poor flame-retardant effect. The method comprises the following steps: firstly, under the protection of a nitrogen gas, performing stirring on dimethyl methylphosphonate, trimethylolpropane and ionic liquid [Bmim] BF4 for 15-25 min to form a mixed solution, continuously introducing a nitrogen gas, performing heating to 140-170 DEG C, continuing stirring, and performing constant-temperature distillation for 14-30 h to obtain a light-yellow solution; and secondly, performing gas chromatographic analysis on the light-yellow solution, performing column chromatography separation, performing