The optimal concentration of nitric acid and sulfuric acid in the preparation of 2,4,6-trinitrotoluene TNT from toluene involves a two-step nitration process. In the first step, toluene is nitrated to form 2,4-dinitrotoluene DNT , and in the second step, 2,4-DNT is further nitrated to form 2,4,6-TNT.For the first step, a mixture of concentrated nitric acid HNO3 and concentrated sulfuric acid H2SO4 is used. The optimal concentration for this step is typically a 1:1 molar ratio of HNO3 to H2SO4. This is because sulfuric acid acts as a catalyst and dehydrating agent, promoting the nitration reaction.For the second step, a more concentrated mixture of nitric acid and sulfuric acid is required to achieve the highest yield and purity of 2,4,6-TNT. The optimal concentration for this step is a 3:1 molar ratio of HNO3 to H2SO4. This higher concentration of nitric acid ensures that the second nitration step proceeds efficiently, while the sulfuric acid continues to act as a catalyst and dehydrating agent.It is important to note that the reaction conditions, such as temperature and reaction time, also play a crucial role in achieving the highest yield and purity of 2,4,6-TNT. The nitration reactions should be carried out at low temperatures 0-5C to minimize the formation of undesired by-products and to ensure the safety of the process, as the reactions are highly exothermic and can lead to runaway reactions if not properly controlled.