"In many ways, he was the most important Philadelphia-area chemist of the last 50 or 60 years," said Arnold Thackray, founding president and chancellor of the Chemical Heritage Foundation, a Philadelphia nonprofit dedicated to preserving the history of chemistry.
In 2005, Mr. McNeil received the prestigious American Institute of Chemists Gold Medal.
Mr. McNeil was born in Bethel, Conn., during a family visit with his maternal grandparents in 1915. His family lived in Germantown, and he graduated from Germantown Academy.
As a chemistry undergraduate at Yale, he took advanced courses with some of the school's most renowned nutrition and pharmacology researchers. After graduating from Yale in 1936, he earned a bachelor of science degree from the Philadelphia College of Pharmacy and Science, now the University of the Sciences.
By then, his family's drugstore, which had rung up just $5.79 in first-day sales, had morphed into a modern pharmaceutical company. It developed and mixed drugs so successfully that the McNeil family abandoned the retail business in the 1920s and shifted to selling to doctors and hospitals. In 1933, the company was incorporated as McNeil Laboratories.
In 1938, Mr. McNeil joined the family business as the first member of its research department, according to newspaper articles.
In the 1940s, McNeil Laboratories decided to come up with an alternative to aspirin that would be available by prescription only. French chemist Charles Gerhardt first discovered the compound that became known as Tylenol in 1852.
But the drug dwelled in obscurity until the late 1940s, when British researchers documented that acetaminophen, the generic name for Tylenol, safely and effectively relieved fevers and pain.
Around the same time, some research linked aspirin to gastric bleeding, making acetaminophen an appealing alternative.
Mr. McNeil, who also had contributed to the development of penicillin, drew on his business skills and scientific prowess to bring acetaminophen to market.
"He was an enterprising fellow, acute, aware, and probing," Thackray said. "He's not like Pasteur. He wasn't in the lab making some brilliant discovery. But he saw all the different pieces and put them together."
The pharmaceutical industry itself was in the early years of a new era. The discoveries of vitamins, insulin, and penicillin in the first half of the 1900s, along with the development of mass-production techniques, had created an enormous business opportunity.
In 1955, McNeil Laboratories introduced its first product under the Tylenol name, Tylenol Elixir for Children.
It eventually became the country's best-selling pain reliever. Today, the brand remains so powerful that adult Tylenol products generate about $1 billion in yearly U.S. sales, even though they compete with shelves full of similar pills and liquids, many of them cheaper generic versions.
Tylenol's long history has not been trouble-free. In 1982, Tylenol capsules tainted with cyanide led to seven deaths in the Chicago area and a national spate of copycat product tampering. The manufacturer was cleared of responsibility in the scare, but whoever was responsible was never found.
Earlier this month, McNeil Consumer Healthcare voluntarily shut down the Fort Washington plant where it produces Children's Tylenol and dozens of other recalled over-the-counter medications in response to an FDA report that said contaminated raw ingredients had been used in some of the products. The plant remains shut.
All of that happened long after Mr. McNeil left the company.
In 1957, McNeil Laboratories moved to a 90-acre site in Fort Washington. It later added 20 acres, and Johnson & Johnson maintains operations under the McNeil name there today.
In 1959, Mr. McNeil and his brother, Henry McNeil, sold the business to Johnson & Johnson for company stock then valued at $33 million. Henry McNeil died in 1983.
As chairman of McNeil Laboratories, Mr. McNeil often promoted and defended his industry. In 1960, he defended pharmaceutical companies against criticisms that advertising and promotional costs were making drugs unaffordable. "The mass sales volume created by these means actually has resulted in dramatic reductions in the prices paid for such health-giving products as penicillin, the sulfa drugs, steroids, and others of great benefit to mankind," he said then.
Mr. McNeil remained chairman of McNeil Laboratories until 1964.
He is survived by his wife, Nancy McNeil; daughters Victoria McNeil Le Vine and Joanna McNeil Lewis; sons Collin Farquhar McNeil and Robert Lincoln McNeil III, also known as Rory; and 11 grandchildren.
"He was a wonderful father who gave so much to us, and one of the reasons why he ultimately started to wind down some of his business ventures was to commit more time to us," Rory McNeil said.
Mr. McNeil channeled his fortune into the Barra Foundation, based in Wyndmoor, and in its most recent tax return reported about $76 million in assets. The name came from the Isle of Barra off the west coast of Scotland, the ancient home of the Clan Macneil.
Rory McNeil said his father enjoyed taking the entire family to the island for reunions.
"The whole family got together and celebrated not only the love we have for each other but for his heritage," he said.
The Barra Foundation gives grants in the five-county Philadelphia area to arts and culture, education, health, and human-services organizations. A foundation gift of about $5.5 million helped get the $17.5 million McNeil Avian Center, an 11,000-square-foot exhibit hall that houses 120 birds at the Philadelphia Zoo, off the ground in 2009.
Joanna McNeil Lewis, a zoo board member and bird enthusiast, was central in securing the donation.
Mr. McNeil was also very generous to his alma maters. In recent years, he gave $8 million to Yale to endow a professorship in physiological chemistry and to fund promising researchers at its medical school.
At the time, he said he wanted to memorialize his mentors, Louis S. Goodman and Alfred Gilman, both doctors and Yale professors who wrote a classic text, The Pharmacological Basis of Therapeutics.
Major buildings on the University of the Sciences in Philadelphia and University of Pennsylvania campuses, built with donations from Robert and Henry McNeil, memorialize the family name.
A passionate scientist, Mr. McNeil also loved American history, arts, and decoration. For many years, he was a trustee at the Philadelphia Museum of Art.
Several million in gifts over almost 15 years funded the University of Pennsylvania's McNeil Center for Early American Studies, which supports research into histories and cultures of North America in the Atlantic world before 1850.
Penn already had a program in early American studies when Mr. McNeil donated an initial $6 million, prompting the university to rename the center in his family's honor.
"He's really allowed what was a significant but small and underfunded program to become a world-class organization," said Daniel Richter, a Penn history professor and director of the McNeil Center. "He was in many ways the perfect benefactor. He was very interested in what we were doing. He would make a point of coming to our seminars once or twice a year . . . but never in any micromanaging kind of way."
Mr. McNeil suggested the center's book series, which includes such titles as Rum Punch and Revolution: Taverngoing and Public Life in Eighteenth-Century Philadelphia.
At Barra, he also encouraged the publication of books focusing on American decorative arts. Some of them, including Official White House China, 1789 to the Present, have become definitive texts.
The foundation's most notable book was Philadelphia: A 300 Year History, published in 1982.
Mr. McNeil also served as a commissioner of the National Portrait Gallery and as a member of the White House Preservation Committee.
Donations in his memory may be made to the Center for American Art at the Philadelphia Museum of Art, 26th Street and the Benjamin Franklin Parkway, Philadelphia, 19130, or the Community Partnership School, 1936 N. Judson St., Philadelphia, 19121.
Contact staff writer Miriam Hill at 215-854-5520 or email@example.com.