Tylenol is a brand name for the drug acetaminophen, which is a widely used pain reliever and fever reducer. The discovery of acetaminophen dates back to the late 1800s when it was first synthesized by French chemist Harmon Northrop Morse [3]. However, it was not until the mid-20th century that acetaminophen became widely used as a pain reliever.

In 1955, McNeil Laboratories, a subsidiary of Johnson & Johnson, introduced Tylenol to the market as a prescription drug [2]. At that time, it was marketed as a safer alternative to aspirin, which can cause stomach irritation and bleeding.

In the 1960s, McNeil Laboratories developed a new formulation of Tylenol that was available over-the-counter (OTC) without a prescription [2]. This made Tylenol more accessible to the general public and contributed to its widespread use.

The exact process by which the inventor of Tylenol discovered the drug is not mentioned in the sources provided. However, it is clear that the development of Tylenol was a result of ongoing research and innovation by McNeil Laboratories.

In conclusion, Tylenol is a brand name for the drug acetaminophen, which was first synthesized in the late 1800s. McNeil Laboratories introduced Tylenol to the market in 1955 as a prescription drug and developed a new OTC formulation in the 1960s. The exact process by which the inventor of Tylenol discovered the drug is not mentioned in the sources provided.

Sources:
[2] https://www.nytimes.com/2010/06/04/business/04mcneil.html
[3] https://www.acs.org/molecule-of-the-week/archive/a/acetaminophen.html