the reaction solution was adjusted to 3 0 by the addition of an aqueous solution of 85 mass phosphoric acid wako pure chemical industries ltd the resulting reaction solution was purified by extraction with 575 g of ethyl acetate and 178 g of ion exchanged water the aqueous layer was collected washed twice with one liter of ethyl acetate and once with one liter of hexane followed by the addition of 6 7 mg of 4 hydroxy 2 2 6 6 tetramethylpiperidinyl n oxyl affording 236 2 g of n 2 2 2 aminoethoxy ethoxy ethyl methacrylamide monophosphate 15 0 mass aqueous solution yield 43 1 h nmr 400 mhz d 2 o u03b4 5 69 s 1h 5 32 s 1h 3 7 3 5 m 8h 3 25 t j 5 6 hz 2h 3 19 t j 5 6 hz 2h 1 80 s 3h n 2 aminoethyl methacrylamide monophosphate m 1 was synthesized in the same manner as in synthesis example 1 except that the amount of benzoic acid was changed as shown in table 1 44 1 g of diethylene glycol bis 3 aminopropyl ether tokyo chemical industry co ltd 96 2 g of ion exchanged water and 96 2 g of methanol were added to a three neck flask of one liter the internal temperature of the flask was cooled to 5 u00b0 c 48 9 g of benzoic acid wako pure chemical industries ltd was added to the flask and then 61 7 g of methacrylic anhydride sigma aldrich co llc was added dropwise thereto over a period of one hour while maintaining the internal temperature at 5 u00b0 c or below after completion of the dropwise addition the mixture was stirred.