Method for preparing sodium 2-hydroxyl-4-methoxyl benzophenone-5-sulfonate

The invention discloses a method for preparing sodium 2-hydroxyl-4-methoxyl benzophenone-5-sulfonate. The method comprises the following steps: adding pure water and 2-hydroxyl-4-methoxyl-5-sulfonic acid-benzophenone into a reaction kettle, adding a sodium hydroxide solution into a dripping storage tank, after 2-hydroxyl-4-methoxyl-5-sulfonic acid-benzophenone in the reaction kettle is completed dissolved, slowly dripping the sodium hydroxide solution into the reaction kettle until the pH value of the solution in the reaction kettle is 5.5-6.5, stopping dripping, cooling to be the room temperature, and performing centrifugal filtration, thereby obtaining a crude product sodium 2-hydroxyl-4-methoxyl benzophenone-5-sulfonate; adding an ethanol solution into the crude product sodium 2-hydroxyl-4-methoxyl benzophenone-5-sulfonate, heating to be 70-75 DEG C, keeping the temperature, when the system is clear, cooling to be the room temperature, and performing centrifugal filtration, thereby obtaining sodium 2-hydroxyl-4-methoxyl benzophenone-5-sulfonate. The method disclosed by the invention is simple in process, simple and convenient to operate and high in product purity.