History of aspirin Hermann Hildebrandt). In 1894, the young chemist Felix Hoffmann joined the pharmaceutical group. Dreser, Eichengrün and Hoffmann would be the key figures in the development of acetylsalicylic acid as the drug Aspirin (though their respective roles have been the subject of some contention). In 1897, Hoffmann started working to find a less irritating substitute for salicylic acid. It is generally accepted that he turned to this idea because his father was suffering the side effects of taking sodium salicylate for rheumatism. In 1853, Charles Frédéric Gerhardt had published the first methods to prepare acetylsalicylic acid. In the course of his
Pyrophosphoric acid Pyrophosphoric acid Pyrophosphoric acid, also known under the name diphosphoric acid, is colorless, odorless, hygroscopic and is soluble in water, diethyl ether, and ethyl alcohol. The anhydrous acid has two different forms, which melt at 54.3 °C and 71.5 °C. It is best prepared by ion exchange from sodium pyrophosphate or by reacting hydrogen sulfide with lead pyrophosphate. When phosphoric acid is dehydrated pyrophosphoric acid is produced as one of the products. When molten, pyrophosphoric acid rapidly forms an equilibrium mixture of phosphoric acid, pyrophosphoric acid and polyphosphoric acids. The percentage by weight of pyrophosphoric acid is around 40% and