[blaper4876]

My question is in regards to a lab we are doing and I just don’t understand this one part, we synthesized aspirin by use of salicylic acid + acetic anhydride one of our post lab questions is “What is the purpose of the phosphoric acid in your reaction?”. Now I know it is used as a catalyst but I am not sure for what. Please explain….sorry for such a rudimentary question but I am really not that good at Orgo or any other Chem and need all the help I can get…

Thanks in advance
Brian

[plu]

Acid catalyses the synthesis of aspirin from salicylic acid and acetic anhydride by improving the quality of the ^-OOCCH₃ leaving group from the anhydride to a much stabler HOOCCH₃.  It'd be a good idea to take a look at the mechanism of the reaction between salicylic acid and acetic anhydride if you are unsure of how the synthesis works