He is known for developing the highly successful anti-gonorrhea drug Protargol, the standard treatment for 50 years until the adoption of antibiotics, and for his pioneering contributions in plastics: co-developing (with Theodore Becker) the first soluble cellulose acetate materials in 1903, called "Cellit", and creating processes for the manufacture of these materials which were influential in the development of injection moulding.

[1] During World War I his relatively non-flammable synthetic cellulose acetate lacquers, marketed under the name "Cellon", were important in the aircraft industry.

Nonetheless, Bayer has denied these claims indicating that Hoffman already figured as the inventor in the American patent of aspirin filed in 1899.

In May 1944, he was arrested again on the same charge and deported to the concentration camp Theresienstadt, where he spent 14 months until the end of World War II in Europe, escaping death.

Due to the rise of the Nazis in Germany, Eichengrün was unable to object when Hoffmann first made the claim that he (Hoffman) invented aspirin, in the footnote of a 1934 German Encyclopedia.

Five years later, Arthur Eichengrün published a paper in Pharmazie in 1949, where he explained that he had instructed Hoffmann to synthesise acetylsalicylic acid and that the latter had done so without knowing the purpose of the work.

[6] Walter Sneader based his claims that Eichengrün both invented the process for synthesizing aspirin and oversaw its clinical testing on old and newly released archived materials, including letters, patents, and lab work.

He found that Hoffmann was not credited with inventing the process for synthesizing Aspirin in any documents prior to 1934, 37 years after its initial synthesis.

Further he found reason to doubt the footnote's credibility, not just for being published during the "Aryanization" period of Nazi Germany, but for its inaccurate claims about the testing of salicylic acid derivates other than acetyl ester.

[7] No indication was given of what the others were, but in 1899 Heinrich Dreser, head of the experimental pharmacology laboratory at Elberfeld, named them in a publication as propionyl, butyryl, valeryl, and benzoyl salicylic acids.

Numerous documents, including Hoffmann's laboratory journal entry from August 10, 1897, explicitly record his synthesis of ASA, providing clear evidence of his role in this pivotal discovery.

Eichengrün’s assertions lack timely credibility, as he did not claim credit for the synthesis until 1949—more than 50 years after Hoffmann's documented work.