The optimal temperature and concentration of nitric acid for the preparation of 2,4-dinitrophenol from phenol via nitration are as follows:Temperature: The nitration reaction is typically carried out at a temperature range of 0 to 5C. This low temperature helps to control the reaction rate and minimize the formation of undesired by-products.Concentration of Nitric Acid: A mixture of concentrated nitric acid HNO3 and concentrated sulfuric acid H2SO4 is used for the nitration process. The concentration of nitric acid should be around 65-70%, while the concentration of sulfuric acid should be around 98%. The ratio of sulfuric acid to nitric acid should be approximately 1:1.Changing these parameters can affect the yield and purity of the final product in the following ways:1. Temperature: Increasing the temperature can lead to a faster reaction rate, which may result in the formation of undesired by-products, such as trinitrophenol or other isomers. This will decrease the yield and purity of the desired 2,4-dinitrophenol. On the other hand, if the temperature is too low, the reaction rate may be too slow, leading to a lower yield.2. Concentration of Nitric Acid: If the concentration of nitric acid is too high, it can lead to the formation of undesired by-products, such as trinitrophenol or other isomers, which will decrease the yield and purity of the desired 2,4-dinitrophenol. If the concentration is too low, the reaction rate may be too slow, leading to a lower yield.In summary, maintaining the optimal temperature and concentration of nitric acid is crucial for the successful preparation of 2,4-dinitrophenol from phenol via nitration, as it ensures a high yield and purity of the final product.