McNeil was not a brilliant synthetic chemist discovering new compounds through long hours in the laboratory, said Arnold Thackray of the nonprofit Chemical Heritage Foundation, whose goal is to preserve the history of chemistry. Instead, he had the insight to discern that paracetamol, also known as acetaminophen, had the potential to become an important drug and the creativity to develop an effective marketing campaign.
Paracetamol was discovered by French chemist Charles Gerhardt in 1852, but the discovery languished for nearly a century until British researchers in the late 1940s demonstrated that it could safely and effectively alleviate pain and reduce fevers. About the same time, other research began to link excessive aspirin use to gastric bleeding and other problems.
Nonetheless, pharmaceutical companies were not interested in developing paracetamol because they feared that it would take sales away from their profitable aspirin products.
McNeil, research director for his family-owned McNeil Laboratories, saw a niche for the drug, guessing successfully that it could be marketed as a safe product for children. After commissioning safety and efficacy trials to obtain Food and Drug Administration approval, the company began marketing Tylenol Elixir for Children in 1955 as a prescription-only product. It was sold in a box shaped like a fire engine and carried the slogan "for little hotheads."
Eventually, the elixir and other Tylenol products for children and adults became available without prescriptions and the brand became one of the best-known drug names. Annual sales exceed $1 billion a year, despite the plethora of generic and branded products that compete with it.
Robert Lincoln McNeil Jr. was born in 1915 in Bethel, Conn., during a visit to his mother's parents. He graduated from Yale University in 1936, then earned a bachelor's degree from the Philadelphia College of Pharmacy and Science, now the University of the Sciences, in 1938.
After graduation, he joined the family business, which had been started by his grandfather as a neighborhood pharmacy in 1879. By the 1920s, the company had abandoned retail sales and was manufacturing drugs for sale to doctors and hospitals. It incorporated as McNeil Laboratories in 1933.
In 1955, Robert Sr. retired from the company and Robert Jr. became chairman of the board; his brother Henry became president. In 1959, the pair sold the company to Johnson & Johnson for about $33 million in stock. Robert Jr. remained as chairman of McNeil Laboratories until 1964 to ease the transition to corporate ownership.
After retirement, he became an active philanthropist, establishing the Barra Foundation — named after the McNeil clan's ancient home, the Isle of Barra off the west coast of Scotland — which gave generously to many Philadelphia-area institutions.
In 2005, he received the prestigious American Institute of Chemists Gold Medal for his pioneering work on acetaminophen — a name, incidentally, that he coined. A colleague suggested Tylenol, an abbreviation of the chemical name N-acetyl-p-aminophenol, for the brand name.
McNeil is survived by his wife, the former Nancy McKinney; two daughters, Victoria Le Vine and Joanna Lewis; two sons, Collin and Robert III; and 11 grandchildren.