1. Write the reaction involved in the synthesis of Aspirin. Acetylation, a type of nucleophilic ac yl substitution is a reaction employed in the synthesis of aspirin. It involves acid- catalyzed reaction of an acetyl group (-COCH3) with a hydroxyl group (-OH) of an alcohol and phenol producing a functional group, ester. In the experiment, acetic anhydride is the source of the acetyl group which is a carboxylic acid derivative. Salicylic acid on the other hand, is the source of the hydroxyl group which is an aromatic compound. Carboxylic acid is the acid catalyst used in the process. The synthesis of aspirin involves acetylation, the acid catalyzed reaction of acetyl ( – COCH 3 ) group with a hydroxyl ( –OH) group of an alcohol and phenol, yielding an ester. Acetylation is a t ype of nucleophilic acyl substituion, and it is also closely relat ed to esterification (the difference being that esterification involves a carboxyl group, not acetyl). In this experiment, the source of the acetyl group is acetic anhydride, a carboxylic acid derivative; the source of the hydroxyl group is salicyclic acid, an aromatic compound; and the acid catalyst is carboxylic acid. 3. Explain why in the recrystallization of Aspirin the water should not be heated above 80°C.The water should not be heated at a temperature above 80˚C in the recrystallizaion of aspirin in order to avoid the hydrolysis of ester which will reverse the reaction, producing carboxylic acid as a reactant instead of ester as a product. The recrystallization of aspirin in water must not exceed a temperature of 80°C in order to prevent hydrolysis of the ester, which will reverse the reaction, yielding reactant (carboxylic acid) instead of product (ester). 4.Explain the results obtained when Aspirin and salicyclic acid were treated with FeCl3 . A purple or violet coloration was observed when FeCl3 reacted to phenol which indicates a positive result. If the synthesized product gives a purple or violet color with FeCl3 solution, this means that not all of the salicylic acid has been used up. Ferric chloride reacts with phenol to give a purple solution. Since salicylic acid has a phenol group, it is expected to give a positive result, that is, become purple. If the synthesized product gives a purple color with ferric chloride solution, it means that not all of the salicylic acid has been consumed.
