As a French prisoner, he was assigned to a gas works in Le Havre, France, where he became interested in chemistry.
His adviser was Otto Diels who together with Kurt Alder, received the Nobel Prize in Chemistry in 1950.
The LHRI was founded by Stanley P. Reimann and Frederick Hammett in 1927 as one of the first U.S. laboratories devoted to fundamental cancer research.
In 1940 Toennies was the first to point out the probable biological importance of sulfonium compounds – a prediction later borne out by a variety of findings by other investigators.
Later, he was the first to demonstrate that the red blood cells are a major site of bound forms of folic acids, a group of vitamins that play an important role in rapid growth of tissues such as occurs in cancer.