The optimal reaction conditions for the synthesis of aspirin from salicylic acid and acetic anhydride are as follows:1. Molar ratio: The stoichiometric ratio of salicylic acid to acetic anhydride is 1:1. However, to drive the reaction to completion and achieve a higher yield, it is common to use an excess of acetic anhydride. A molar ratio of 1:1.2 salicylic acid:acetic anhydride is often used.2. Reaction temperature: The reaction is typically carried out at a temperature of 80-90C. This temperature range allows for a faster reaction rate while minimizing the risk of side reactions and decomposition of the reactants.3. Reaction time: The reaction time can vary depending on the specific conditions and the desired yield. Generally, a reaction time of 15-30 minutes is sufficient for the synthesis of aspirin. Longer reaction times may be necessary if lower temperatures are used.4. Catalyst: The addition of a catalyst, such as concentrated sulfuric acid or phosphoric acid, can help increase the reaction rate and improve the yield. A few drops of the catalyst are usually sufficient.After the reaction is complete, the mixture is cooled, and the aspirin product is isolated by filtration or crystallization. The crude aspirin can then be purified by recrystallization from an appropriate solvent, such as ethanol or water.