Direct oxidation of an aldose affects the aldehyde group first, converting it to a carboxylic acid, and most oxidizing agents that will attack 1o alcohol groups will also attack 2o alcohol groups. Clearly, then, a laboratory synthesis of a uronic acid from an aldose requires protecting these groups from oxidation. Keeping this in mind, suggest a method for carrying out a specific oxidation that would convert D-galactose to d-galacturonic acid.