by dissolving levofloxacin in a polar solvent at an elevated temperature and crystallizing purified levofloxacin preferably an antioxidant is added to increase the purity application_number US 3715205 A description crude and semi pure preparations of levofloxacin can be prepared by methods known in the art alternatively levofloxacin crude can be prepared for example by the following method in a 1 liter reactor equipped with a mechanical stirrer a condenser and a thermometer heated at 80 u00b0 c is charged 87 5 g 0 31 mole of s u2212 9 10 difluoro 3 methyl 7 oxo 2 3 dihydro 7h pyrido 1 2 3 de 1 4 benzoxazine 6 carboxylic acid 61 3 ml dmso and 86 3 ml 0 77 mole of n methylpiperazine the slurry is stirred at a rate of 250 rpm under nitrogen atmosphere at 80 u00b0 c until completion of the reaction monitoring by hplc then the slurry is cooled to 75 u00b0 c and a mixture of isopropanol 675 ml and water 25 ml is added dropwise at this temperature over 2 hours the slurry is then cooled to 5 u00b0 c over 4 hours maintained at this temperature for 2 hours and filtrated under vacuum at this temperature the solid is then washed with 175 ml of isopropanol 2 rinses and dried under vacuum to obtain levofloxacin crude in one embodiment of the present invention crude levofloxacin is purified as used herein u201c purified levofloxacin.