Richard Kuhn

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(b. Vienna-Dobling, Austria, 3 December 1900, d. Heidelberg, Germany, 31 July 1967),

chemistry. For the original article on Kuhn see DSB, vol. 7.

More than thirty years after the death of Nobel Prize laureate Richard Kuhn, one of the most distinguished and successful biochemists in twentieth century, his role as a scientific administrator in the Nazi regime was critically debated for the first time. During his lifetime Kuhn’s personal involvement in research on chemical Weapons of Mass Destruction and his collaboration in the persecution of Jewish scientists and his cooperation with the secret state police (Gestapo) was not discussed in public. It was not before the end of the Cold War that historical research was able to access declassified archival documents in the United States, Great Britain, and Germany, shedding light on Kuhn’s role as an influential scientist in Nazi Germany.

At the time of the Nazi takeover in 1933, Kuhn headed the Institute for Chemistry, one of four institutes comprising the Kaiser Wilhelm Institute (KWI) for Medical Research in Heidelberg. Due to the acting director’s illness, Kuhn became provisional head of all four institutes in March 1934. His appointment as overall director of the KWI was affirmed in January 1938. After the installation of the anti-Semitic “Law for the Restoration of Professional Civil Service” in April 1933, Kuhn did nothing to protect Jewish assistants at the KWI, unlike his colleague, the Nobel Prize laureate Otto Meyerhof, director of the Institute of Physiology. Even though Meyerhof himself faced persecution as a Jew, Kuhn, as provisional director, in a letter to the general administration of the Kaiser Wilhelm Society (KWS), demanded that Meyerhof should be instructed to dismiss three Jewish researchers working at the institute. Kuhn’s demand was rejected by the general administration of the KWS, as it was not yet illegal to accept Jews as PhD candidates (Deichmann, 2000; Schmaltz, 2005).

Kuhn never joined the Nazi Party. However, party officials and the Gestapo described him as politically reliable and loyal to the regime. He rose to be one of the most influential scientific organizers of biochemistry in the Nazi era. Before World War II he held important positions in scientific organizations, expert councils, and governmental research organizations. He was a member of the executive boards of the Emil Fischer Society, which financed the KWI for Chemistry, and the Adolf Baeyer Society for the Promotion of Chemical Publications, and he served on the scientific committee of the Society of German Natural Scientists and Physicians. He was vice-chairman of the Justus Liebig Society, a foundation supporting German post-doctoral students in chemistry; chairman of the working group for organic chemistry of the Verein Deutscher Chemiker, and, in 1936, vice president of the Union Internationale du Chimie. After his 1937 appointment to the executive board of the German Chemical Society (Deutsche Chemische Gesellschaft, DChG), he participated in the society’s nazification by actively adapting the society’s statutes to the Nazi

Führerprinzip (principle of leadership), abolishing the society members’ right to elect their own executive board and president.

In March 1938 Kuhn was appointed president of the DChG, a post he held until 1945. In a speech as president of the DChG in 1942, Kuhn praised the “fighting front” of the nations that had joined the Anti-Komintern powers, hailing Mussolini, the Japanese emperor, and Hitler. One month after the German attack on Poland, Kuhn became head of the branch (Fachspartenleiter) for organic chemistry of the Reich Research Council (Reichsforschungsrat). Though sources are fragmentary, it is certain that Kuhn supported at least eight research projects on chemical warfare agents and gas defense as Fachspartenleiter in 1943–1944 alone. In 1942 Kuhn became senator of the Reichsfachgruppe Chemie of the Nationalsozialistischer Bund Deutscher Technik, a federation associated with the Nazi Party. In September 1944 Kuhn was appointed to the Wehrforschungs-Gemeinschaft, an agency coordinating war research efforts with the Armament Ministry led by Albert Speer and Four Year Plan agencies.

In 1938, during the intense preparation for the war, Kuhn’s KWI for Medical Research cooperated with the Army Ordnance Office (Heereswaffenamt), doing chemical warfare research. His assistant, Christoph Grundmann, conducted an investigation on vitamin B6 (adermin, pyridoxine). Grundmann was exploring the effectiveness of vitamin B6 in the treatment of lesions caused by mustard gas. In March 1939 Grundmann tried to sell a patent on the synthesis of vitamin B6 to the Swiss chemical company Hoffmann La Roche. In Kuhn’s opinion, these efforts endangered his cooperation with the German military and chemical industry (I. G. Farbenindustrie and Merck). Kuhn accused his assistant of treason, denouncing him to the Gestapo. Grundmann was dismissed without notice, then was arrested and later tried in a secret trial, which ended in a dismissal. The charge of treason was dropped, as there had been a prior application for a similar patent in the United States, before Grundmann’s imprisonment. Further studies showed that vitamin B6 had no therapeutic effect on wounds caused by mustard gas. The vitamin research by Kuhn and collaborators, mentioned in the article on Kuhn by Dean Burk in the Dictionary of Scientific Biography, was therefore embedded in a military context. This is also true for the synthesis of “numerous analogues and reversibly competitive inhibitors (“antivitamins”) mentioned by Burk.

Anti-vitamin research by Kuhn and some of his pupils in Heidelberg during World War II played an important role for investigations of a new group of nerve gases, discovered earlier in 1936 (Tabun) and in 1938 (Sarin) in the context of pesticide research by I.G. Farbenindustrie. After lengthy negotiations, collaboration between Kuhn and the Army Ordnance Office was finally transformed from assigned research contracts to the formal institutionalized establishment of a secret laboratory for chemical warfare research at the KWI for Medical Research. This laboratory, led by Kuhn, was set up in the period of preparations for the invasion of the Soviet Union in January 1941 as an outpost of the gas defense department of the Army Ordnance Office. One third of the academic staff at the institute for chemistry was taken over. Among those were Helmut Beinert, Otto Dann, Konrad Henkel, Dietrich Jerchel, Günter Quadbeck, and Friedrich Weygand. This new department was established in the rooms at the Institute of Physiology, which were available as a result of the displacement of Otto Meyerhof, who had fled Germany in September 1938 due to increased anti-Semitic harassment. Pharmacological studies on the treatment of mustard gas lesions were conducted there by Kuhn’s assistant Günter Quadbeck, who detected a certain therapeutic effect of a cyclic carbon-hydrogen on such wounds. But the main emphasis of the scientific research done at the chemical warfare department in Heidelberg consisted of investigating the effects of the nerve gases Tabun and Sarin. The experiments at the KWI also included the search for possible antidotes and other poisonous nerve gases.

Internationally, the KWI for Medical Research was one of the leading institutes in the field of vitamin research. Starting out with tested methods from vitamin research, the team led by Kuhn succeeded in determining the mode of action of nerve gases in 1943. They identified the strong inhibition of acetyl cholinesterase—which is vitally important for the stimulus-conducting function of the neurotransmitter acetylcholine in the brain—as the most significant effect. The hypothesis put forward by the Military Medical Academy scientists, stating that the effects of nerve gas were caused by additional enzyme systems, was therefore refuted. On the basis of the inhibition of acetyl cholinesterase, the team in Heidelberg developed a specific testing technique for the degree of toxicity of nerve gases. In the spring of 1944 Kuhn and his PhD candidate Konrad Henkel synthesized Soman, which proved to be stronger than Tabun and Sarin. Soman was not produced on an industrial scale until the end of the war. It is still one of the most effective chemical weapons to date.

In the spring of 1943 Kuhn asked the secretary-general of the KWS, Ernst Telschow, to support his search for the brains of “young and healthy men,” presumably for nerve gas research. The sources indicate that these brains were most likely taken from execution victims. If and to what extent cerebrums were indeed delivered from morgues in Heidelberg and Stuttgart to the KWI for Medical Research has not yet been established with certainty. There is also no proof that KWI scientists participated directly in human experiments conducted in concentration camps. But Kuhn, as head of the special branch, together with Karl Brandt, who was the commissioner for public health and sanitation and largely responsible for the so-called Euthanasia program, authorized the use of funds from the Reich Research Council for the phosgene experiments on prisoners, carried out by the physician Otto Bickenbach, in the gas chamber of the concentration camp Natzweiler-Struhof in 1944. Bickenbach was tried as a war criminal at a French military tribunal in 1947. His experiments had caused at least four Roma or Sinti (Gypsies) to suffocate painfully. Kuhn justified the experiments as “scientifically outstandingly profound.” Kuhn ignored the context of genocide and insisted that this research had pursued “a high aim for the whole of humanity” and were “beneficial for many” (Kuhn to Eber, 5 August 1947, Archives of the Max Planck Society, III. Abt., Rep. 25, no. 54).

After the liberation, Kuhn did not fully inform the experts of the Allied military intelligence about the chemical warfare research. His institute suffered only few importunities—but not, as Burk suggested, because of Kuhn’s plant color experiments for a U.S. colonel’s wife, but rather because of the lack of information about his role during the Nazi era, and because after 1945, his chemical warfare research was of great interest to the Chemical Warfare Service. In July 1945 Kuhn continued chemical warfare research under Allied authority, despite the strict prohibition of military research in Germany. When U.S. intelligence and military services set up a recruitment program for German and Austrian scientists and technicians under the codename Operation Paperclip, Kuhn denied two offers (1947 and 1949) to continue chemical warfare research in the United States.

In 2005, as a result of historical research, the Society of German Chemists (Gesellschaft Deutscher Chemiker, GDCh) declared their intention to no longer award the Richard Kuhn Medal: “The board of the GDCh intends to discontinue awarding the Medal named after the organic chemist, Nobel Prize laureate of the year 1938 and President of the GDCh in 1964–65, Richard Kuhn. The board thereby draws the consequences out of research on Richard Kuhn’s behaviour during National Socialism. Even though the question of whether Kuhn was a convinced National Socialist or just a career-oriented camp follower is not fully answered, he undisputably supported the Nazi-regime in administrative and organizational ways, especially by his scientific work. Despite his scientific achievements, Kuhn is not suitable to serve as a role model, and eponym for an important award, mainly due to his unreflected research on poison gas, but also due to his conduct towards Jewish colleagues” (Nachrichten aus der Chemie 54, May 2006, p. 514).


A bibliography of Kuhn’s publications is provided by Selchow Christian, “Richard Kuhn (3 Dez. 1900 Wien–31 Juli 1967 Heidelberg).” Archiv zur Geschichte der Naturwissenschaften 10 (1984): 473–497.


Kuhn, Richard. “Ansprache von Richard Kuhn auf der Besonderen Sitzung am 5. Dezember 1942.” Berichte der Deutschen Chemischen Gesellschaft 75 (1942): 147–202.


Adamson, D. W., D. C. Evans, C. W. Scott, et al. KWI für medizinische Forschung, Heidelberg—Target No. 8/58 & 24717 (2.5.1945). CIOS Evaluation Report 10, 1945.

Baader, Gerhard, Susan E. Lederer, Morris Low, et al. “Pathways of Human Experimentation, 1933–45: Germany, Japan, and the United States.” In Politics and Science in Wartime: Comparative International Perspectives on the Kaiser Wilhelm

Institute, edited by Carola Sachse and Mark Walker. Chicago: University of Chicago Press, 2005.

Deichmann, Ute. “Kriegsbezogene biologische, biochemische und chemische Forschung an den Kaiser Wilhelm-Instituten für Züchtungsforschung, für Physikalische Chemie und Elektrochemie und für Medizinische Forschung.” Geschichte der Kaiser-Wilhelm-Gesellschaft im Nationalsozialismus: Bestandsaufnahme und Perspektiven der Forschung, edited by Doris Kaufmann, vol. 2. Göttingen, Germany: Wallstein-Verlag, 2000.

———. Flüchten, mitmachen und vergessen: Chemiker und Biochemiker in der NS-Zeit. Weinheim, Germany, and New York: Willey-VCH, 2001.

Ebbinghaus, Angelika, and Karl Heinz Roth. “Vernichtungsforschung: Der Nobelpreisträger Richard Kuhn, die Kaiser Wilhelm-Gesellschaft und die Entwicklung von Nervenkampfstoffen während des ‘Dritten Reichs.’” 1999. Zeitschrift für Sozialgeschichte des 20. und 21. Jahrhunderts 17 (2002): 15–50.

Edson, E. F., D. C. Evans, R. E. F. Edelstein et al. Interrogation of Certain German Personalities Connected with Chemical Warfare. BIOS Final Report 542. London: H. M. Stationery Office, 1946.

Ruske, Walter. 100 Jahre Deutsche Chemische Gesellschaft. Weinheim, Germany: Verlag Chemie, 1967.

Schmaltz, Florian. Kampfstoff-Forschung im Nationalsozialismus: Zur Kooperation von Kaiser-Wilhelm-Instituten, Militär und Industrie. Göttingen, Germany: Wallstein Verlag, 2005.

———. “Neurosciences and Research on Chemical Weapons of Mass Destruction in Nazi Germany.” Journal of the History of the Neurosciences 15 (2006):186–209.

———. “Otto Bickenbach’s Human Experiments with Chemical Warfare Agents at the Concentration Camp Natzweiler in the Context of the SS-Ahnenerbe and the Reichsforschungsrat.” In Man, Medicine and the State: The Human Body as an Object of Government Sponsored Research in the 20th Century, edited by Wolfgang U. Eckart. Stuttgart, Germany: Steiner, 2006.

Florian Schmaltz

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Kuhn, Richard

(b. Vienna-Döbling, Austria, 3 December 1900; d. Heidelberg, Germany, 31 July 1967)


Kuhn, the son of Richard Clemens and Angelika (Rodler) Kuhn, was taught by his mother until he entered the Döbling Gymnasium at the age of nine, where he remained for eight years until drafted into the army. Four days after his release on 18 November 1918, he entered the University of Vienna. After three semesters he proceeded to the University of Munich, where his experimental genius soon became evident. In 1922 he obtained his Ph.D. under Willstätter and not long afterward received his docentship; he became widely known as Willstätter’s greatest discovery.

In 1926 Kuhn moved to Zurich to become professor of chemistry at the Eidgenössische Technische Hochschule. In 1928 he married Daisy Hartmann; they had two sons and four daughters. In 1929 he was appointed director of the new Chemistry Institute of the Kaiser Wilhelm Institute for Medical Research at Heidelberg and professor at the university, where he remained for the rest of his life, notwithstanding later offers from Berlin, Munich, Vienna, and the United States.

In 1937 Kuhn became director of the entire Kaiser Wilhelm Institute for Medical Research, and in 1946–1948 helped to transform the Kaiser Wilhelm Society for Scientific Research into the Max Planck Society for the Advancement of Science. He was a charter member of the society’s senate and later served as vice-president under Otto Hahn and then Adolf Butenandt. His scientific papers numbered over 700, his students and collaborators over 150, and his distinctions over fifty, including the 1939 Nobel Prize in chemistry.

Kuhn demonstrated his major scientific traits—discipline and precision coupled with imagination and fantasy—in both his 1922 doctoral thesis, “Zur Spezifität von Enzymen imKohlenhydratstoff wechsel” (“On the Specificity of Enzymes in Carbohydrate Metabolism”), and 1925 Habilitation thesis, “Der Wirkungsmechanismus der Amylasen; ein Beitrag zum Konfigurations—Problem der Stärke” (“Mechanism of Action of Amylases”). They dealt with greatly improved enzyme adsorption and elution carrier materials and kinetic enzyme measurements applied to a variety of sugar derivatives (glycosides, oligosaccharides, and polysaccharides). Specificity problems led him inevitably to problems in optical stereochemistry that preoccupied him for the rest of his life. He began research on additions on ethylene bonds; thus, addition of hypochlorous acid to fumaric or maleic acid resulted in chloromalic acid and also in ring closure to form ethylene oxide dicarboxylic acid. This work led in Zurich to studies on inhabited rotation among diphenyls, especially ortho-substituted derivatives. Kuhn showed that benzidine was stretched out on a plane, with the two NH2—groups about 10 Å apart, instead of angled back and only about 1.5 Å apart. Kuhn, like Pasteur, had early dominating experiences with different forms of isomerism, and, like van’t Hoff, had a remarkable understanding of stereoisomerism.

With further studies on the activation energies of rotation among ortho-substituted diphenyls, Kuhn and his collaborators arrived at quantitative concepts of the spatial needs of particular groups, including the concept of “atropisomerism,” long before the terms “conformation” and “constellation” gained acceptance and applicability not only to substituted compounds but also to totally unsubstituted ones as in trans-cycloocten.

Proceeding to the preparation of diphenylpolyenes containing conjugated double bonds (—CH=CH—)n added in unbroken order, Kuhn and his collaborators showed that the diphenyls were colorless when n = 1 or 2, but colored for n = 3 to 15. They thereby definitely established the existence of colored hydrocarbons. Research on crocetin, bixin, and most important, carotene (in crystallizable α, β and γ forms) demonstrated that Kuhn-type polyenes are found in nature. Work on carotene proved that symmetrical provitamin A yields two molecules of water. Among the synthetic polyenes, it was found that the position of the longest wavelength maximum

.λ = K“; n1/2 K”

helped to determine the structures of natural carotenoids.

Kuhn next attacked water-soluble vitamins. He showed vitamin B2. isolated and crystallized from milk and named lactoflavin, to be part of Warburg’s yellow enzyme’ and he synthesized and structurally identified the vitamin. He prepared lactoflavin identified the vitamin. He prepared lactoflavin phosphate and, after combining it with the protein carrier of the yellow enzyme, he found it to be enzymatic ally identical with the reversible yellow oxidation enzyme (yellow flavin ⇋ colorless leukoflavin), and that identifiable intermediate stages displayed free radical paramagnet ism and dimerism. Kuhn then identified vitamin B6 (adermin, phridoxine), p-aminobenzoic acid, and pantothenic acid and synthesized numerous analogues and reversibly competitive inhibitors (“antivitamins”). It was for the his work on carotenids and vitamins that Kuhn was awarded the Noble prize.

From the 1950’s on Kuhn worked on and identified various “resistance” factors effective against infection—nitrogenous oligosaccharides isolated from human milk; brain gangliosides; and potato alkaloidglycoside (demission), active against larvae of potato beetles. Of especial interest was the finding that lactaminyl (sialic acid) oligosaccharides could be split by influneza virus and also by the receptor-destroying enzyme (RDE) of cholera vibrio (α-ketosidas action). Lactaminyl oligosaccharide was recognized as a receptor for influenze virs; therefore the virusinhibiting action of human milk (compared with bovine, which does not contain lactaminyl oligosaccharide) was explained: cells that do not form lactaminyl-oligosaccharide structures on their surfaces show resistance to influenza virus. Some twenty-five papers on the isolation and synthesis of amino-sugar saplit products of N-oligosaccharides followed.

Like Pasteur of France and Virtanen of Finland, Kuhn of Germany and Austria developed over the years intens interest in applications of his academic researches to medicine and agriculture. At the end of World War II Kuhn demostrated experimentally to a U.S, Army colonel’s wife that the she could trun green plants into red plants by adding triphenyltetrazolium chloride to the nutrient medium and so the institute was spared molestation.


The complete scientific works of Kuhn have not yet been published; the most complete review is in the 63-page supp. to the Mitteilungen aus der Max-Planck-Gesellschaft zur Foerderung der Wissenschaften (1968), which the lists over 100 references to the most important works of Kuhn and his collaborators.

Dean Burk

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Richard Kuhn (rĬkh´ärt kōōn), 1900–1967, Austrian chemist, director of the Kaiser Wilhelm Institute, Heidelberg. For his research on the carotinoids (he prepared eight of them in pure form) and on vitamins (he isolated riboflavin, or B2) he was awarded the 1938 Nobel Prize in Chemistry. A Nazi decree prevented his acceptance of the award until after World War II. Kuhn also isolated vitamin B6.

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Kuhn, Richard (1900–1967) Austrian chemist; isolated and purified carotenoids, riboflavin and vitamin B6. Nobel Prize 1938, but a Nazi decree prevented his acceptance until after World War II.