Letter from Richard Willstatter to Michael Heidelberger

Heidelberger had helped to synthesize cyclooctatetraene, the next higher analog of benzene (consisting of a ring with eight carbon atoms and four double bonds), during a year of postdoctoral study (1911-12) in the laboratory of the 1915 Nobel Laureate, Richard Willstatter, at the Federal Polytechnic Institute in Zurich, Switzerland. His research with Willstatter on cyclooctatetraene was controversial, and was questioned as late as the 1940s by Hugh S. Taylor and Charles D. Hurd. In this letter, Willstatter admitted to being "shaken up" by Taylor and Hurd's criticism, which he concluded was due to a misreading of his and Heidelberger's evidence and to ignorance on their part of the chemistry of hydrocarbons of the cyclooctane series. He urged Heidelberger to publish a defense of their research.

In his correspondence with Taylor and Hurd, Heidelberger stood firmly by his and Willstatter's results, pointing out that while Taylor and Hurd showed that cyclooctatetraene resinifies and degrades at high temperatures, he had instead worked in cold temperatures continuously for 24 hours to synthesize a colorless liquid that was both stable and reactive. Heidelberger and Willstatter's results were confirmed by others, and as a consequence of their work cyclooctatetraene became a widely used intermediate in organic chemistry.

In addition, Willstatter congratulated Heidelberger on his research with phosphorylated egg albumin as an antigen for use in precipitin reactions, which Willstatter predicted would open a "new field of work" in immunology.