Letter from Michael Heidelberger to Charles D. Hurd, Northwestern University

Heidelberger had helped to synthesize cyclooctatetrene, 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 cyclooctatetrene was controversial, and was questioned as late as the 1940s by Hugh S. Taylor and Charles D. Hurd. Heidelberger, however, strongly defended his results, as documented in this letter, pointing out that while Taylor and Hurd showed that cyclooctatetrene resinifies and degrades at high temperatures, he had worked in cold temperatures continuously for 24 hours to synthesize a colorless liquid that was both stable and reactive. Heidelberger and Willstatter's results stood, and as a consequence of their work cyclooctatetrene became a widely used intermediate in organic chemistry.