Derivative of phosphonic acid and process for the preparation thereof

A process for the preparation of 2,5-dicarboxyphenyl phosphonic acid, comprising the steps of:

• forming a reaction liquid phase by supplying 2,5-dialkylphenyl phosphonic acid, a solvent, a cobalt salt, a manganese salt and/or a cerium salt, and bromine or a bromine compound into a reaction zone;
• and
• supplying oxygen into the reaction liquid phase by bringing an oxygen-containing gas into contact with the reaction liquid phase by supplying an oxygen-containing gas into the above-mentioned reaction zone.

A process for the preparation of 2,5-dicarboxyphenyl phosphonic acid, comprising the steps of:

• forming a reaction liquid phase by supplying 2,5-dimethylphenyl phosphonic acid, acetic acid, a cobalt salt, a manganese salt and/or a cerium salt, and bromine or a bromine compound into a reaction zone;
• and
• supplying oxygen into the reaction liquid phase by bringing an oxygen-containing gas into contact with the reaction liquid phase by supplying an oxygen-containing gas into the above-mentioned reaction zone.