Felix Hoffmann in 1890 with the pharmaceutical state exam. In 1891 he graduated magna cum laude from the University of Munich. Two years later he earned his doctorate, also magna cum laude, after completing his thesis entitled "On certain derivatives of dihydroanthracene". In 1894, he joined Bayer as a research chemist. On 10 August 1897 Hoffmann synthesized acetylsalicylic acid (ASA) while working at Bayer under Arthur Eichengrün. By combining salicylic acid with acetic acid, he succeeded in creating ASA in a chemically pure and stable form. The pharmacologist responsible for verifying these results was skeptical at first, yet once several large-scale studies
History of aspirin preparations became a standard part of the "materia medica" of Western medicine beginning at least with the Greek physician Hippocrates in the fifth century BCE; he recommended chewing on willow bark to relieve pain or fever, and drinking tea made from it to relieve pain during childbirth. The Roman encyclopedist Celsus, in his "De Medicina" of ca. 30 AD, suggested willow leaf extract to treat the four signs of inflammation: redness, heat, swelling and pain. Willow treatments also appeared in Dioscorides's "De Materia Medica", and Pliny the Elder's "Natural History". By the time of Galen, willow bark was commonly used