On August 10, 1897, Hoffmann synthesized acetylsalicylic acid (ASA) for the first time in a stable form usable for medical applications. Bayer marketed this substance as Aspirin.
Hoffmann was also the first to create a stable version of Diacetylmorphine or Heroin, but he was not its original inventor, despite the claims of the Bayer company.
Following the synthesis of aspirin, Hoffmann moved to the pharmaceutical marketing department, where he stayed until his retirement in 1928.
He died on February 8, 1946.
In 1949, Arthur Eichengrün published a paper in which he claimed to have planned and directed the synthesis of Aspirin along with the synthesis of several related compounds. He also claimed to be responsible for Aspirin's initial surreptitious clinical testing. Finally, he claimed that Hoffmann's role was restricted to the initial lab synthesis using his (Eichengrün's) process.
The Eichengrün version was ignored by historians and chemists until 1999, when Walter Sneader of the Department of Pharmaceutical Sciences at the University of Strathclyde in Glasgow re-examined the matter and concluded that Eichengrün's account is convincing and correct and that Eichengrün deserves credit for the invention of Aspirin.
Bayer promptly denied this theory in a press release, claiming that the invention of Aspirin was due to Hoffmann.
In 2002, he was inducted into the US National Inventors Hall of Fame.