Benzoxazinone derivative is one of starting materials in the synthesis of Deferasirox (a Chelating iron for thalassemia patient). The parameters of Benzoxazinone derivative synthesis were investigated from the condensation of salicylic acid, salicylamide,�cyanuric chloride, and triethylamine using toluene as solvent. The mole equivalent ratio of salicylic acid: salicylamide:cyanuric chloride:triethylamine at 1:1:0.67:1 provided the 46.77% yield of Benzoxazinone derivative in laboratory scale. Surprisingly, 4-chloro-2-(2-hydroxyphenyl)-4H-benzo[e][1,3]oxazine-4-ol was observed in the synthesis of Benzoxazinone derivative. In addition, the reaction scheme of Benzoxazinone derivative synthesis was proposed as a model for the study of the chemical kinetic constant.� Furthermore, the scale up of Benzoxaxinone derivative synthesis was studied from laboratory scale to 1-L reactor and 10-L reactor using the mole equivalent ratio from laboratory scale.� The result revealed that the mixing speed at 200 rpm of 10-L reactor�gave 43.18 % yield.�It was found that the scale-up process involved using a constant tip speed, as the solid was formed in the reaction system. As a result, the same shear force would produce the same size of the solid. Consequently, the solid in the reaction mixture could dissolve and be transformed into the product.