In addition to chemicals such as ammonia, nitrous ether, chloroform, and acetic and carbolic acids, Mallinckrodt also purifed uranium oxide that was used in the world’s first self-sustaining nuclear reactor during the 1940s. This process led to the production of the first atomic bomb.

In 1954, Mallinckrodt stock was made public and in 1960, under its new president, Harold Thayer, the company was reorganized into Medicinal, Industrial, Chemicals and Nuclear divisions. I In the 1960s-90s, Mallinckrodt acquired many other businesses, including Nuclear Consultants and Washine Chemical Corporation. In 1977, its headquarters moved from downtown St. Louis to West St. Louis County.

In 1982, Avon Products bought Mallinckordt, Inc. and then sold it to International Minerals and Chemical Corporation (which later changed its name to IMCERA Group Inc.) in 1986. In 1989, Mallincordt was divided into two independent companies, Mallinckrodt Medical and Mallinckrodt Specialty Chemical Company.

Mallinckrodt merged with Tyco International in 2000 and became part of Tyco Healthcare.

The company has funded many civic ventures and contributed greatly to Washington University. The university houses the Mallinckrodt Department of Pediatrics, the Mallinckrodt Department of Pharmacology, the Mallinckrodt Institute of Radiology, and the Mallinckrodt Center for the Performing Arts. [St. Louis:Home on the River, p. 248-249, http://www.mallinckrodt.com/corpprofile/cp-history.html]